MXPA97006680A - System of surround sound socks of theater in c - Google Patents

Abstract

The present invention relates to an apparatus for realistically reproducing sound, particularly for sound based on a stereophonic signal having dialogue and effects and associated with an accompanying video image. The apparatus includes a front speaker located in proximity to the video image to provide acoustic output based on a sum signal of the left and right component channels (L + R) of the audio signal. A rear speaker located at the rear of the viewing area provides acoustic output based on a difference signal (L - R) or (R - L) between the left and right channels. The left and right horns are located on the respective left and right sides of the viewing area. The left channel speakers reproduce in one mode, the respective left and right channels of the audio signal and in a second mode reproduce a difference signal (L -áR) or (R -ÁL), where it is a gain that can vary It can be a fixed value between zero and unity. Output to the left and right speakers is band-limited to substantially facilitate frequency components below a predetermined threshold. A lower speaker can also be provided to output the low frequency components of a sum signal (L + R). The sum signal (L + R) that is fed to the front speaker helps in locating dialogue in the video image. The difference signal (L -áR) or (R -ÁL) substantially removes dialogue sound in such a way that the output from the side and rear speakers, primarily comprises sonic environment and surround or surround sound effects. The band feed from the left and right speakers also helps in locating dialogue in the video image. Alternately, even in another embodiment, a monophonic signal may be applied at least to one modality of the system to allow production of a spatially enhanced surround sound effect.

Description

SYSTEM OF SURROUNDING SOUND BORNS OF THEATER AT HOME This application corresponds to a continuation-in-part of the patent application of the U.S.A. Serial No. 08 / 525,364, filed September 7, 1995. BACKGROUND OF THE INVENTION Technical Field This invention relates generally to the reproduction of stereophonic sound and more particularly to the reproduction of stereophonic sound associated with a video image so such that dialog is located in the video image and sound effects and environment, are reproduced in a way that immerses the audience in a realistic three-dimensional sound field. Discussion. In the past, numerous monophonic and stereophonic sound systems have been developed in an attempt to achieve high-fidelity sound reproduction. Initial efforts restricted the concept of high fidelity when playing monophonic audio signals. These early efforts focused on producing a speaker enclosure that meets performance criteria defined by measurable acoustic characteristics such as frequency response, distortion and dynamic range. The speakers include an enclosure that contains one or a number of acoustic transducers and intended divider networks to reproduce the full range of audibility frequency. As an example of this multiple transducer of this multiple transducer and divider configuration, a three-way speaker design includes a speaker transducer to reproduce low frequencies, a mid-range transducer to reproduce mid-range frequencies and a transducer for tweeter reproduce high frequencies. The typical divider network described above mixes the acoustic output of the speaker transducers to achieve good tonal balance characterized by a smooth transition in acoustic output from one transducer to another. One way to achieve this is a symmetric divider network that functions as a filter to ensure the dispersion of response of a transducer, since the frequency increases through the transition region is an image in the mirror of the response increment of a accompanying transducer that reproduces the adjacent upper frequency sound band. An adequate implementation of this design approach requires that the combination of transducers and divider networks does not introduce audible artifact (an unnatural sound quality) resulting from frequency response irregularities or phase cancellation effects that potentially result in housing a multiplicity of transducers in a speaker enclosure. Early attempts at high fidelity through monophonic audio signals and three-way divider networks eventually resulted in the reproduction of stereophonic sound. The first stereophonic systems used a pair of identical spatially distributed high-fidelity speakers to reproduce two audio signal channels. This spatial distribution of two speaker cabinets is fundamental to the concept of stereo sound reproduction. A stereo image results when the acoustic output of the speaker pair merges into the stereo image perceived as a horizontal sound panorama. This sound panorama creates for the audience a stereo sound image that spans the space between the two speaker locations. A proper stereo perspective results from a person listening, placed on an axis between the two speakers and perpendicular to the plane of the speakers. Most of the speakers used in stereophonic systems project sound in a direct path from the speaker to the listener, referred to as direct radiation. In an attempt to expand the stereo image, designers have employed pairs of speakers that radiate a combination of direct and reflected sound. This configuration expands the stereo image beyond the space between the two speakers. Some more contemporary stereo sound systems use three-part sub-satellite speaker systems, wherein a combination of subwoofer base unit for low frequencies and a pair of satellite speakers replace the pair of conventional full-range speaker enclosures, described above. In these three-piece speaker systems, the satellite speakers reproduce a wide spectrum of medium and high frequency sounds, while the bass unit only reproduces very low frequency sounds. Restricting bass reproduction to the subwoofer unit for low frequencies allows satellite speakers to be relatively small in size compared to traditionally large stereo speaker cabinets, whose large size is dictated by large transducers and enclosures required to achieve good base response. Many consumers prefer this smaller satellite speaker array versus the more traditional full-range speaker cabinets. The bass unit can be placed out of sight and the satellite speakers blend more easily with the decoration of the room. However, other consumers still see these satellite speaker boxes somewhat smaller as unpleasant and difficult to incorporate into the home environment, in a discreet way. Despite the improvements in total sound quality that are provided even by the most sophisticated systems, be it a pair of stereo speakers or a three-part sub-satellite system, many consumers find that contemporary sound systems lack the sense of sonic realism associated with live sound. Each sound reproduction system, while complying with quantitative acoustic performance criteria with respect to the frequency, distortion and dynamic range response, can subjectively evoke a wide range of perceptions for the listener of sonic realism from a qualitative point of view . Some systems determined to sound more realistic, have also found creating a sense of amplitude in the reproduced sound. This determination has provided the basis for extensive developments in the field of acoustics in order to achieve an improved spatial quality for reproduced sound while avoiding the introduction of sonic artifact that could deteriorate the total sonic experience. The previously described three-part sub-satellite speaker system extends the concept of spatially distributing speaker components such as a pair of stereo speakers. The concept can still be further extended by spatially distributing a substantial number of point sources, to reproduce sound in an auditorium environment to further increase the perceived spaciousness. While adding a multiplicity of spatially distributed point sound sources can increase the perception of spaciousness, it can also produce an exaggerated, bombastic spatial presentation that lacks realism. This reproduction of unnatural sound often causes the listener to experience acoustic fatigue. In this way, the enhanced spaciousness must be balanced with the perceived acoustic realism of the resulting sound field in order to fully satisfy the listener. This balance is particularly important in home theater sound systems, where the acoustic requirements for this application differ from those for stereo music sound reproduction. The key objectives for a home theater sound system, are (1) to establish a convincing surrounding acoustic sound atmosphere, based on the environment and audio signals and sound effect captured on the track; (2) maintaining a panorama of stereo sound image in front of the viewer; and (3) play dialogue that remains located on the video screen for all viewers in the room. In essence, satisfactory acoustic performance results when the listener is immersed in a sound field that has three-dimensional spatial quality perceived as authentic in relation to the visual presentation on the video screen. Initial attempts to produce a theater or movie theater sound at home include placing a pair of traditional speakers on either side of a centrally located video display. These systems improved against the sound of speakers included in the typical television equipment. However, the performance of these systems is determined unacceptable in the market for at least two reasons. First, the people who listen located outside the central line between the two speakers will not find dialogue on the screen (that is, they will perceive the dialogue that only comes from the screen). The dialog is typically recorded in both left and right channel signals. The dialogue location will be an equidistant point between the two speakers for the person listening on the center line between the speakers. As the listener moves out of the center line, it will move closer to one speaker and farther away from the other. The location of the dialogue will move to the address from which the first signal that arrives originates. This will be the nearest speaker. The dialogue is lost in the near speaker as the listener moves off the axis. The location of the dialogue will be shifted from the location of the video image when the listener is off the axis, and the illusion that the characters on the screen are actually speaking for people who listen outside the axis will be destroyed. Second, a pair of stereo speakers located on either side of the visual display confines the sound field to the space in front of the person listening on the speaker plane. In this way, there is no sense of immersion - a sense that sound events occur next to or behind the listener as well as in front of the listener. Many systems have been designed in an attempt to remedy these deficiencies. For example, Patent of the U.S.A. No. 3,697,692. granted to Hafler, discusses using technology to recover the environment. Hafler uses the fact that surrounding sound information resides in virtually all of the stereo audio signals, be it music recordings or the sound track of the video program material, and that they can be recovered. The recovery results from obtaining the difference signal between the left and right channel (L - R) leaving alone, substantially the ambient portions of the signal. This minus left (L - R) difference signal reproduced by the speakers placed in the back of the auditorium room provides the recovered surround or surround sound information. Another theater sound system in the previous alternate home, added an additional center channel to play a left plus right signal (L + R) to improve the quality of dialogue sound playback. The center channel is combined with subsequent sound horns that reproduce a left minus left (L - R) signal similar to the room recovery horns described above. An example of this system has been developed by Dolby Laboratories under the name DOLBY SURROUND. The central speaker to reproduce the signal (L + R), as incorporated in the DOLBY SURROUND systems, improves on the effect of convenient location of dialogue for people who listen outside the axis. However, the reproduction of the central channel (L + R) does not completely solve the problem of displacement between the audience and the visual images, for people who listen outside the axis. These systems still suffer from location errors for dialogue (and other signals encoded in the sum signal) because passive decoding schemes such as DOLBY SURROUND are only able to achieve a maximum adjacent channel separation of 3 dB (where Adjacent channels are defined as center and right, center and left, left and envelope, right and envelope). A difference of 3 dB in level between the dialogue in the center channel and dialogue in the left and right channels is not enough to confine the location to the location of the center channel speaker for all the positions of the listener through a typical auditorium room. The location still moves to the nearby speaker for people who listen outside the axis. Having the dialogue lost in the nearby speaker is common to all passive decoder systems of the prior art. In an alternative approach to the DOLBY SURROUND systems, a configuration structure T proposed by the US Patent. No. 4,612,663, issued to Holbrook, provides surround or surround sound by passively decoding the signals in stereo. The T configuration includes left and right speakers that reproduce the respective left and right signals, a third speaker that reproduces the difference signal (LR) placed halfway between and in the plane of the right and left speakers, and a fourth speaker that reproduces the difference signal placed after the listener. However, this approach fails to maintain a rational sonic image in situations where the stereo signal temporarily has predominantly left or right channel energy and also fails to avoid the perception of dialogue emanating from the near left or near right speaker. Another system that uses the difference (L-R) and (R-L) signals can be found in US Pat. No. 5,027,403, granted to Short and collaborators. Short discusses using left and right channels directed to the front to provide sound output in the direction of the listener. Short also discusses directing bass signals (L + R) backwards from the general plane of the video perception area. Short also discusses directing signals (L-R) and (R-L) backward or sideways from the general vicinity of the video image. However, Short suffers from the disadvantage that all the sound emanating from the speakers emanates from the video image. This substantially planar sound radiation does not fully provide the effect of surround sound and the environment. Another example of a system having speakers arranged in a generally planar configuration can be found in U.S. Patent No. 4,497,064, issued to Polk. Polk also discusses fixing left and right main speakers and additional sub-horns arranged in proximity to the main speakers, to provide the listener with an expanded acoustic image during stereo sound reproduction. However Polk maintains specific limiting system requirements, including that the speakers are equidistant from the listener in order to ensure the arrival of sound to the listener within a predetermined period of time. Polk also discusses high pass filtering of an inverted version for a main horn signal, to send output from the opposite side sub-horn. This high-pass filtering cancels the main speaker component on the opposite side, which would otherwise reach the ear of the listener in which it is filtered. However, high-pass filters are not aimed at canceling low-frequency components to maintain location of voice information to a video image. Polk also specifically requires that all speakers in the system remain substantially in the same plane and radiate in the direction of the listener. The Polk system will also not be able to keep location of program material equally recorded on the left and right channels to the area centered between the two speakers for people who listen outside the axis. The location of these signals will move toward the nearby speaker for people listening off the axis.

Examples of non-planar speaker configurations include U.S. Pat. No.4, 443, 889, granted to Norgaard. Norgaard discusses the use of a left front speaker and a right front speaker, to reproduce the stereo signals of respective left and right channels. Norgard also discusses the use of a difference series (L - R) through a rear speaker to create an ambience signal. However, among other things Norgaard does not consider combining the signals (L + R) through a central speaker to locate better dialogue in the video image. The U.S. Patent No. 5,181,247 granted to Holl, discusses similar concepts regarding the use of difference signals (L-R) and (R-L). However, Holl does not illustrate the use of a single speaker to output an addition signal (L + R). Neither Holl suggests band limitation of the signal feed to the room speakers. The U.S. Patent No. 4,819,269, given to Klayman, discusses radiating sound based on a sum signal in a limited space pattern and radiating sound based on a signal of difference in a broad scattering pattern. The radiated signals combine acoustically with the intention of improving the stereo sound in the listening area. However, Klayman specifically requires specialized wide dispersion tubes or sets of multiple transducers to achieve the desired effect described. In addition Klayman does not discuss excluding the range of primary frequencies of vocal energy from the output of either speaker to locate better dialogue in the central speaker. Other perimetric sound systems use complex signal processing in an attempt to improve the apparent separation between each of the left-center and right-center left channels. The most common system of that type in use today is the DOLBY PRO-LOGIC decoding system, this system improves upon solutions to the basic problems of many passive decoding systems of the prior art described above. Active electronic circuits are used to decode matrix encoded audio signals, introduce time delays and achieve direction between channels through auto gain control circuits. However, improved performance requires a substantially higher expense because DOLBY PRO-LOGIC requires a minimum of four separate amplification channels. In addition, by their very nature, active electronic signal processing systems, potentially introduce sonic artifact (an abnormal sound quality that can destroy the sense of realism (in its response) .A form of such artifact in the DOLBY PRO-LOGIC system it results from active duration circuits that vary the amount of adjacent channel signal subtracted from the signal, for example, when dialogue is present and it is desired to locate them to the center, the center channel signal is subtracted from the left channel signals and the right to withdraw dialogue energy from these channels This variable subtraction consists in dynamically varying the channel separation to maintain primary location in a particular direction Frequently listeners can listen to the environment (which creates atmosphere in the audio presentation) video) that goes in and out as the dialogue enters or leaves the scene Shrinkage and growth The environment that accompanies the introduction and termination of dialogue distracts the listener and proves to be a clear disadvantage of this active electronic component approach particularly to home-theater sound reproduction. Another disadvantage to DOLBY PRO-LOGIC is that it only works properly with coded program material. Uncoded material or material that has degraded in some way may confuse the logic circuits and cause a strange extreme spatial effect to occur when the encoder directs localization in a way that was not intended. Another major disadvantage of the DOLBY PRO-LOGIC decoding system includes its high cost to the consumer and its inherent complexity that makes it difficult for the consumer to install and use the system properly. More recently, there has been a return for trying to provide perimetric sound systems, passive and economical, less complex. An example of these systems is that in the U.S. Patent. No. 5,386,473, granted to Harrison. Harrison addresses the use of a transformer that passively decodes line-level stereo television output signals that require further amplification to produce the high-level signal needed to drive the speakers. The transformer receives signals from left feed channel and right channel and provides left front, right front, left rear (L-R) channels, right rear (R-L), center (L + R) and sub-speaker for low frequencies. Harrison is based on transforming low level signals specifically to solve perceived problems resulting from the use of speakers connected to high level amplifier outputs, in order to obtain a perimetric sound effect. However, Harrison cites disadvantages in successfully operating a passive surround sound system in high-level signals. The present invention is specifically directed to using high level signals to provide surround sound while overcoming the aforementioned problems with respect to the high level systems discussed by Harrison, such as the expenditure of high energy components, balance problems and the like. Other recent attempts at passive decoding include the QD-1 Series II decoder manufactured by Dynaco. The QD-1 Series II decoder receives amplifier signals in stereo. The decoder then produces four (or five) signals - two front speakers, two rear speakers and an optional center channel horn. A second similar decoder is the HTS-1 decoder manufactured by Chase Technologies. Similar to QD-1 the Chase decoder receives signals from the amplifier and then generates signals for a pair of front speakers and a pair of rear speakers. The Chase Decoder also produces a signal for an optional amplified center channel speaker. These last two passive decoders suffer from two primary disadvantages. First, the resistor network used to produce a signal (L + R) for the center channel, dissipates energy thereby requiring an amplifier or stereo receiver of sufficiently high energy to overcome this loss of energy. Preferably, it is to provide a system in which all the loudspeakers of the system are routed through a low-power amplifier such as is found in a television or acoustic box with single-frequency resonance, portable, where no energy is wasted in the networks of signal summing resistors. In one of the previous systems, the center channel horn must be energized in order to generate the desired function of maintaining dialogue location in the physical location of the central speaker. Second, because a certain amount of signal (L + R) feeds the subsequent surround speakers, artifact in terms of dialogue emanating from the subsequent surround speaker may occur in this way disturbing the realism of the intended environment effect. In this way, there is a need for a system of perimetric sound horns for home theater, which operates using relatively simple passive electronic components, in order to limit its cost and thus provide an attractive system for the mass market at a reasonable cost. . Of particular importance to these systems is the convenience of presenting a consistent ambient sound field while maintaining localized dialogue to the video image for all positions in the auditorium and vision area. The dialogue and visual images also preferably coincide in the video image and preferably do not move relative to one another in a particular speaker address. In addition, audio designers have devoted substantial and particular attention to designing speaker systems that reproduce left and right channel audio signals from a stereophonic signal, to create a sonic effect of three-dimensional perimetric sounds. However, the audio designers have substantially ignored the monophonic sound market. Many consumers still have monophonic television equipment that outputs only a monophonic channel, instead of left and right channel components of a stereo signal. This currently relegates the consumer who has a monophonic television, to have sound that emanates only from the location of the television equipment. In addition, while the AM stereo continues to be discussed and can be used by a few limited stations, most AM broadcasts remain monophonic. Finally, many programs available on television, VCR, cable, satellite and other stereo audio / video signal supply systems have monophonic soundtracks. Some audio / visual receivers for domestic and stereo theater apply signal processing techniques to the monophonic sound signal, to produce spatial sound effect in stereo or enhanced. This signal processing typically involves additional and complex circuits for digital signal processing and filtering and phase shifting. The consumer in this way must absorb the expense in acquiring this receiver, a perimetric sound decoder or other electronic sound processing device and a convenient speaker network, to achieve a three-dimensional spatial effect or simulated stereo from an audio signal. monophonic Therefore, there is a need to provide a low-cost system for effectively reproducing monophonic audio signals in a form that creates a convincing three-dimensional sonic effect. In addition to the obvious convenience of a home theater perimetric sound system, which provides all the benefits described above, a more practical logistical problem exists in a home theater system. That is, as domestic theater systems continue to evolve, a growing number of additional components are technically required. These components often include active electronic controllers, numerous speaker connections, auxiliary control modules and separate audio system interconnections. This mess of components often confuses the average consumer during installation. Despite numerous attempts by manufacturers to make the installation more user-friendly and facilitate the installation procedure, many users experience difficulties in properly installing the system. The most recent attempts to facilitate the installation process have involved color coding of the speaker connections and the audio signal source in addition to labeling the connection plugs for the user to see, and providing detailed and complete installation instructions . For many reasons, these measures have failed in proportion to the consumer with a sufficiently easy way to install sound systems in home theater correctly, and many consumers are faced with the expense of a professional installation. In this way, it is also convenient to provide a perimeter home theater sound system, which greatly facilitates the installation in such a way that the consumer can install in a relatively fast, easy and correct way and operate the system, thus improving the attractiveness of the system. massive market. OBJECTIVE OF THE INVENTION The present invention achieves numerous objectives based on the novel application of a variety of acoustic design principles and through a novel combination of separation of adjacent channels and individual channel operating bandwidth.

An objective of the present invention is to create a realistic sound field to accompany video presentations that locate dialogue to the video screen for all the people who listen through the area of perception, while maintaining a three-dimensional sound field, spacious and consistent. A further object of the present invention is to provide a low cost sound reproduction speaker system, which produces a comparable or superior authentic home theater surround sound with that which is provided with multi-surround sound matrix decoding systems. active, complex and expensive electronic channels. A further object of the present invention is to passively decouple the reproduction of ambient audio signals and dialogue to avoid ambient instability artifact associated with electronic signal processing and to ensure the presentation of a convincing integration of sonic and visual images. A further object of the present invention is to provide spacious sound reproduction of conventional audio signal sources such as stereo signals of two-channel matrix or stereo, without the need for electronic components for auxiliary matrix decoding.

A further object of the present invention is to provide a system of speakers for sound reproduction that produce a spatially enhanced surround sound sonic effect for a monophonic audio signal. A further objective of the present invention is to provide a speaker system that is relatively simple and straightforward to install and operate by the average consumer, including providing error-free connections by the consumer in a relatively short period of time. A further objective of the present invention is to provide a speaker system that connects easily and directly to a television set in stereo, without need for an additional audio-video amplifier or receiver. A still further object of the present invention is to provide a perimeter home theater sound at normal home listening levels, using the low wattage power amplifier or equivalent available in commercial stereo TV sets. A further object of the present invention is to provide a speaker system having an operating principle and extremely small size incorporating tiny satellite speakers that can be discreetly placed in the home environment without affecting sonic performance. COMPENDIUM OF THE INVENTION In accordance with the principles of the present invention, a system of perimetric sound speakers for domestic theater reproduces in a novel form the stereophonic audio portion of an audio / video presentation in such a way that dialogue is located in the video image and the viewer is immersed in a field of sound that is perceived as authentic when related to the visual image. In a first preferred embodiment of the present invention, the passive non-energized speaker system includes a front speaker, a front speaker, a left speaker, a right speaker and a rear speaker, each speaker receives an electrical power signal and provides an acoustic signal according to the power supply signal. The front speaker is located in proximity to the video image and provides an acoustic output according to a leftmost right sum (L + R) of the left and right channels of the stereophonic signal, so that the dialogue is located in and matches the video image. The left and right speakers may be coplanar with the front speaker, but preferably located between the viewer and the front speaker, and on the left and right sides of the viewing area, respectively. The horns provide acoustic output according to respective left and right stereo channels. The rear speaker is located at the rear of the perception area and provides acoustic output according to a difference left less right (LR) or right less left (RL) between Stereophonic channel signals. The difference signal is substantially stopped by dialog filtering and provides the audio information of surrounding and ambient sound. The electrical signal feeds of left and right channels to the respective left and right speakers are band-limited to remove substantially all frequency components below a predetermined threshold frequency. Band limiting ensures that the dialogue is located in the front speaker, as the filtrate substantially removes signal energy in the speech signal range from the left and right channel signals reproduced acoustically. In a second preferred embodiment, the non-energized passive speaker system includes a front speaker such as the left speaker, a right speaker and a rear speaker, each speaker receives an electrical power signal and provides an acoustic output according to the power signal electric The front speaker is located in proximity to the video image and provides an acoustic output according to a leftmost right sum (L + R) of the left and right channels of the stereophonic signal, so that dialogue is located in and matches the video image. The left speaker may be coplanar with the front speaker, but preferably located between the viewer and the front speaker, and to the left side of the viewing area. The left speaker provides acoustic output according to an electrical difference feed signal (L- ßR), for example ß is a gain factor that varies between zero and the unit can be a fixed value between zero and unity. Similarly, the right power speaker is located between the viewer and the front speaker, and the right side, of the viewing area. The right speaker provides acoustic output according to a difference signal (R-ßL) for example where ß is a gain factor between zero and unity or it can be a fixed value between zero and unity. The rear speaker is located at the rear of the viewing area and provides acoustic output according to at least one left minus right (L-R) or right minus left (R-L) difference between the stereophonic channel signals. By using the difference signal substantially the dialogue portion of the audio signal is removed thereby leaving the ambient sounds in the difference signals. In this second preferred embodiment, the difference signals fed to the respective left and right horns may also be optionally bandlimited to remove substantially all frequency components below a predetermined threshold frequency. The band limitation of the difference signals substantially removes the low frequency components in the difference signal such that the difference signals can be reproduced using excessively small compact speakers. In the third preferred embodiment, the powered speaker system includes a front speaker, a left speaker, a right speaker and a rear speaker, each speaker receives an electrical power signal and provides an acoustic output in accordance with the power supply signal. Active electronic components preprocess and amplify the left and right channels of the stereophonic signal, to provide a left plus summation signal (L + R) and a difference signal, (L - R), for example. The resulting sum and difference signals drive the individual horns of the speaker system. The front speaker is located in proximity to the video image and provides a series of acoustics according to the sum signal, such that the dialogue is located and matches the video image. The left speaker is located on the left side of the viewing area and provides an acoustic output according to the difference signal (L - R), for example. The right speaker is located on the right side of the viewing area and provides acoustic output according to the difference signal (R-L), for example. The rear speaker is located at the rear of the viewing area and provides acoustic output according to the difference signal. In this third preferred embodiment, the difference signal can be inverted by inverting the plurality applied to a particular speaker. Also, in this third preferred embodiment, the difference signal fed to the respective left speakers may occasionally be band-limited to remove substantially all frequency components below a predetermined threshold and allow reproduction of the difference signals using overly small compact speakers. . In a fourth preferred embodiment, the system includes a front speaker, a left speaker, a right speaker and a rear speaker, each speaker receives an electrical power signal and provides a monophonic acoustic output according to a monophonic power supply signal. The front speaker is located in proximity to the video image and provides an acoustic output in accordance with the monophonic signal. The left speaker can be coplanar with the front speaker, but preferably it is located between the viewer of the front speaker and to the left of the viewing area. The left speaker provides monophonic acoustic output according to a monophonic power signal. Similarly, the right speaker is preferably located between the viewer and the front speaker, and to the right side of the perception area. The right speaker provides a monophonic acoustic signal according to a monophonic power signal. The rear speaker is located at the rear of the viewing area and provides a monophonic acoustic output according to a monophonic power signal. Using the monophonic signal allows users who only have monophonic audio output sources to obtain an enhanced spatial sonic image or a sonic sound effect based on the monophonic signal. The monophonic signal fed to the respective left and right horns is bandlimited, as described herein, to remove substantially all frequency components below a predetermined threshold frequency. The in-band power of the band signal substantially removes the low frequency components in a monophonic signal, so that the signal can be reproduced using relatively small compact satellite speakers. The limitation in band also restricts reproduction of the primary vocal energy to the central speaker. The present invention may also include a power amplifier for receiving left and right power signals and amplifying the left and right power signals to output the respective speakers. An energetic version that has integral amplifiers allows the system designer to generate amplified output signals tailored to the specific speakers selected by the system designer. This integrated design approach facilitates the optimization of the acoustic output of the system. The present invention can also accommodate an additional bass horn for reproducing low frequency components of the stereo signal. The bass speaker only requires generally it is located in the vision area and provides an acoustic output according to the low frequency components of the sum signal (R + L). The present invention also includes an interconnection module to facilitate installation and operation by the user. The interconnect module includes power and output plugs that have a predetermined number of terminals. The predetermined number of signals indicates which signals are fed or output by the plugs. For example, a three-terminal outlet plug sends the output to a left, right and common ground electrical signal respectively. This configuration of the output configuration plugs ensures proper installation of the system because the user can only install the speaker system in a particular configuration. The speaker system design may include an interconnect module as an additional self-supporting component of the system, or it may incorporate the interconnect module circuit with one of the existing components, such as the bass horn or the front speaker. The present invention also includes a wireless implementation. In the wireless implementation, an electrical radio connection provides an audio signal to the interconnection module from the audio signal source. The interconnection module includes active electronic components to produce both difference and sum signals. A radio transmitter receives the difference signal and transmits the signal. Each of the left, right and rear speakers includes a radio receiver tuning the frequeof the transmitter. The reactors then provide an amplified electrical signal suitable for production of an acoustic output by an associated speaker. From the subsequent detailed description taken in conjunction with the accompanying drawings and appended claims, other objects and advantages of the present invention will be apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of the surround sound system for home theater, arranged in accordance with the principles of the present invention; Figure 2 is an expanded block diagram of a first preferred embodiment of the surround sound speaker system for home theater in Figure 1; Figure 3a is an expanded block diagram of a second preferred embodiment of the surround sound speaker system for home theater in Figure 1, where difference signals are output to the left and right satellite horns; Figure 3b is an expanded block diagram of a variation of a second preferred embodiment of the surround sound system of the home theater in Figure 1, wherein the signal subtracted to produce the difference signals is attenuated before subtraction; Figures 4a and 4b are circuit diagrams for high-pass filters respectively first and second order to limit in bandwidth the power signal to the satellite horns left to right; Figures 5a and 5b are circuit diagrams for applying a rightmost left-sum signal. { L + R) to the central speaker, using a simple transducer and a dual transducer configuration, respectively; Figures 6a and 6b are circuit diagrams for applying a left minus right difference (L-R) signal to the rear speaker of the surround sound system of the home theater, using mobile, single and dual coil configurations, respectively; Figure 7 is an expanded block diagram of a third preferred embodiment of the home theater surround sound speaker system, where left and right channel sum and difference signals are actively generated before sending the output to the speakers; Figure 8 is an expanded block diagram of a fourth preferred embodiment of the home theater surround sound speaker system, wherein the monophonic signal outputs each of the speakers; Figure 9 is a wiring diagram for an interconnect module for the home theater surround sound speaker system, used to facilitate installation and error-free operation of the system; Figure 10 is a block diagram of an alternate configuration for the home theater surround sound speaker system, illustrated in Figure 1; Figure 11 is a perspective view of the base sub-speaker unit for low frequencies and interconnection module; Figure 12 is a wiring diagram for the integral interconnect module and base sub-speaker unit for low frequencies of the home theater surround sound system of Figure 11, used to facilitate installation and error-free operation of the system; and Figure 13 is a block diagram for a wireless implementation of the home theater surround sound system. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The following description of the preferred embodiments is simply exemplary in nature and is not intended to limit the invention, its application or uses. In specification, it should be noted that elements that have similar structures or functions will be referred to using similar reference numbers. The modalities described herein provide several improvements relating to the prior art and will be discussed previously at the beginning. First, the invention involves the spatial distribution of several speakers with respect to the auditorium room in order to add the perception of spaciousness to listeners. The spatial distribution includes left and right side speakers, a rear speaker, front (or center) speaker and sub-speaker for low frequencies. Second, this invention involves locating patterns of sound radiation to a front or center speaker to create an illusion to the listener, that certain sound emanates from that speaker. This invention also involves the reproduction of particular sounds to create ambient surrounding sound throughout the room. This preference sound emanates from speakers other than the front or center speaker. Third, this invention involves limitation in frequency band to eliminate particular acoustic frequencies produced by the left and right satellite speakers. The band limiting frequency is chosen according to the desire to eliminate the bocal energy output of the satellite horns. Fourth, this invention involves an atypical overlap of the frequency ranges of the horn components. In this way, each of the front, rear and side speakers has a rather wide range of overlapping frequencies. Fifth, this invention passively outputs the left channel acoustic signals, right channel, left channel more right and left channel less right, using several means to passively generate the signals. Figure 1 illustrates a diagrammatic view of the surround sound speaker system for home theater (the surround sound system) 10 arranged in accordance with the principles of the present invention. The surround sound system 10 includes a source of a preferably amplified stereo signal, illustrated in Figure 1 as a television set 12. The stereo audio source can be any of a number of audio signal sources. In this way it will be noted that the source of a stereo audio signal is represented here as television 12, but the audio signal source can also be a stereo receiver, a car stereo, a tape player or portable compact disc, a single-frequency, portable, portable frequency-based stereo speaker, or any other source of a stereo signal.

The television 12 outputs an amplified audio signal to interconnect the module 14 via a multi-conductor cable 16. The multi-conductor cable 16 typically includes two conductor pairs to carry the left and right channels of the stereo signal output on television 12 to the module interconnection 14. The interconnect module 14 receives the audio signals from the television 12 and assembles the left and right component channel signals for selective distribution to speakers of particular components of the surrounding sound system 10. The component speakers typically include a sub-speaker for low frequencies 18, which receives full-range left and right signals, but only reproduces the low-frequency components of the audio signal. The interconnect module 14 also outputs an audio signal to the front center speaker 20. The front center speaker 20 receives both the left and right component signals from the stereo signal and reproduces the sum signal (L + R). Preferably, the front central speaker 20 is located in proximity to the television 12 and projects the acoustic output of the sum signal (L + R) to the listener 28.

The interconnect module 14 also outputs the left channel signal to the left satellite horn 22, and the right channel signal to the right satellite horn 24. The left satellite horn 22 and the right satellite horn 24 can be relatively small speakers and only need to reproduce high frequency and / or midrange signals. The left and right satellite horns are preferably oriented in such a way that the primary axis of redemption of the horn directs upwards on a vertical axis; however, other orientations of satellite speakers can also provide satisfactory performance. The interconnect module 14 also outputs an audio signal for the rear ambience horn 26. The after ambience horn 26 typically receives an audio signal in the form of a left channel difference signal minus the right channel (L - R) or right channel minus left channel (R - L). As will be apparent from this detailed description, various embodiments of the invention described herein allow the interconnect module 14 to generate a variety of signals to be output to the left satellite horn 22, right satellite horn 24 and / or ambient horn. 26. It should be noted in principle that the term "horn" refers to a system for converting electrical power signals into acoustic output signals, wherein the system may include one or a number of transducers and / or currency networks. The components described in Figure 1 are typically arranged to optimize the surrounding sound effect to enhance the listening experience of the viewer 28. The viewer 28 typically faces the television 12 having a front center speaker 20 disposed in proximity to television 12, in such a way that the central speaker 20 and the television 12 radiate their respective audio and video output in the general direction of the viewer 28. The left satellite horn 22 is typically disposed on the left side of the viewer 28, while the right satellite speaker 24 is arranged on the right side of the viewer 28, both satellite horns are typically nominally located in the middle between the viewer 28 and the television 12. The rear ambience horn 26 that contributes to creating a spacious audio effect is typically located behind the viewer 28. The rear environment horn 26 is illustrated with a single horn, but can be included in the system. ema multiple rear speakers 26. Figure 2 illustrates an expanded block diagram of a preferred embodiment of the present invention. The expanded block diagrams described herein generally include wiring and partial circuit diagrams and will be referred to interchangeably as conformance through this specification as circuit or wiring block diagrams. The surround sound system for home theater 100 (the surround sound system) includes a left side satellite horn 102 (left side satellite horn)right-side satellite speaker 104 (right-side satellite speaker), center speaker 106, surround or rear speaker 108 and sub-speaker horn for low frequencies 110. Left-channel amplifier 112 outputs an amplified left-channel signal that is fed to the positive terminal of the moving coil 114a of the central speaker 106. The negative terminal of the mobile speaker 114a of the central speaker 106 connects to the negative terminal of the left channel amplifier 112. Similarly, the right channel amplifier 116 outputs an amplified right channel signal which is fed to the positive terminal of the mobile coil 114b of the central speaker 106. The negative terminal of the mobile speaker 114a of the central speaker 106 is connected to the negative terminal of the channel amplifier right 116. The left and right channel signals are thus connected in phase to the two movable loudspeakers 114a and 114b of the central speaker 106, of ma nera such that the output of the central speaker 106 is the sum of the left and right channel signals (referred to herein as L + R). The positive terminal of the left channel amplifier 112 also outputs an amplified left channel signal to the positive terminal of the left-side speaker 102 through a filter 118. The negative terminal of the left channel amplifier 112 is connected to the negative terminal of the left side speaker 102. Similarly, the positive terminal of the right channel amplifier 116 also outputs an amplified right channel signal to the positive terminal of the right side speaker 104 through a filter 120. The negative terminal of the right channel amplifier 116 is connected to the negative terminal of the right-side speaker 104. In this manner, in the embodiment of Figure 2, the amplified left and right channel signals are output to the speakers of the right amplifier. left and right side, respectively. The left-side speaker 102 and the right-side speaker 104 are preferably band-limited to reproduce only higher frequencies as illustrated using the left high-pass filter 118 and the right-hand high-pass filter 120. The use of high pass 118 and 120 with respective left and right side horns 102 and 104, limit the acoustic output of the left and right side horns 102 and 104 at high frequencies. As will be described in more detail with respect to Figures 4a and 4b, this limitation in band of the satellite horns 102 and 104 excludes the primary frequency range of the vocal energy. The listener, in this way, perceives the dialogue sound that comes only from the front speaker 20 located in proximity to the video image. Examples of these high-pass filters will be described in greater detail with respect to Figures 4a and 4b. The surround sound system 100 also includes a rear speaker 108. The feeds to the rear speaker 108 provide a left minus left (L-R) difference signal. To effect this difference signal, the left channel amplifier or positive terminal 112 outputs the amplified left channel signal to the positive terminal of the rear speaker 108, and the positive terminal of the right channel amplifier 116 outputs the signal right channel amplified to the negative terminal of the rear speaker 108. The connections described above to the rear speaker 108, provide the desired difference signal (L-R). The rear speaker 108 also includes a potentiometer 109. The potentiometer 109 allows adjustment of the acoustic output of the rear speaker with respect to the output of the other speakers in the system. This output is typically adjusted according to the proximity of the rear speaker to the listener. It will be recognized by a person skilled in the art that an inverted polarity connection to the rear horn 108 provides a difference signal ((R - L) instead of a difference signal (L - R) The polarity of the difference signal radiated by the rear speaker does not significantly affect the performance of the surround sound system 100 and any alternative The surrounding sound system 100 further includes a sub-speaker for low frequencies 110. The positive terminal of the left channel amplifier 112 outputs the amplified left channel signal to the positive terminal of the sub-speaker speaker for low frequencies left 122. The negative terminal of the left channel amplifier 112 is connected to the negative terminal of the subwoofer speaker for left low frequencies 122. Similarly, the positive terminal of the right channel amplifier 116 outputs the amplified right channel speaker to the positive terminal of the right sub-speaker speaker for low frequencies 124. The negative terminal of the right channel amplifier 116 is connected to the terminal negative of the right speaker of sub-speaker for low frequencies 124. Thus, in the embodiment of figure 2, the left channel signal directs the left sub-speaker speaker for low frequencies 122 and the right channel signal directs the right speaker sub-speaker for low frequencies 124 respectively. The resulting output from the subwoofer speakers for low frequencies left and right in this way are added acoustically. It will be understood by a person skilled in the art that the center channel horn 108 can alternatively operate over a full range of frequencies, including the bass range, thereby eliminating the sub-speaker for low frequencies. In an alternative mode to the preferred embodiment described above, the left and right amplifiers 112 and 116 can be integrated into the system. For example, left and right channel amplifiers 112 and 116 while in general are considered by this specification to be cc output amplifiers only found and included in the aforementioned audio signal outputs, can be specifically selected amplifiers, which form a portion of the surrounding sound system 100. Amplifiers 112 and 116 in this alternate mode will receive low level power signals from the audio signal source. The amplifiers 112 and 116 will further amplify the power signal to send output to the surround sound system speakers. To effect such configuration, the output amplifiers 112 and 116 can be incorporated into the interconnection module 14 (as illustrated in Figure 1). The interconnect module 14 will preferably be energized independently to drive the amplifiers 112 and 116. A particular advantage of this alternate configuration is that the output amplifiers 112 and 116 can be designed to specifically integrate with the electrodynamic characteristics of the horn. A preferred embodiment of the surround sound system 100 includes 819.5 cm3 (50 in3) which houses a 8 ohm, dual coil, dynamic electrode with a 7.62 cm (3") diameter, a pair of 100 micro farads capacitors connected in series with the positive output of the left and right channel signals performs a division function.The central speaker 106 has an operating bandwidth about 150 Hz. The rear speaker 108 uses a similar configuration but employs a single voice coil, in Instead of a dual voice coil transducer, the rear horn 108 includes a closed enclosure with approximately 819.5 cm3 (50 in3) and houses a simple 8 ohm mobile coil electroacoustic transducer with a diameter of 7.62 cm (3"). Potentiometer 109 is a potentiometer L, 8 ohms, 15 watts, or a coil of 3 watts, 25 ohms. If the potentiometer 109 allows a variation in the output level of the rear speaker 108. A capacitor of 68 micro farads connected in series with the power supply to the positive terminal of the mobile coil performs a dividing function. The nominal frequency band of the rear speaker 108 is 150 Hz to 8 KHz. The rear speaker 108 reproduces a difference signal (L-R), as described with respect to Figure 2. The side speakers 102 and 104 each comprise in a sealed enclosure of approximately 32.78 cm3 (2 in3) and house a speaker 3.81 cm diameter (1.5") plastic cone treble with nominal 4 ohms impedance commercially available A pair of 4.7 micro farads capacitors connected in series with the positive power supplies to side horns 102 and 104, provides high pass filtering for the left high pass filter 118 and right high pass filter 120. The high pass filters 118 and 120 provide a nominal frequency band of approximately 4 KHz to 15 KHz output from the side horns 102 and 104. The low-frequency sub-speaker 110 is a conventional dual-volume enclosure design consisting of a sealed volume of 9506 cm3 (580 in3) and a nominal port volume of 7,376 cm3 (450 in3) which operates in conjunction with a pair of electro-dynamic coil transducers of 4 ohms, with diameter of 13.34 cm (5.25") .A pair of inductors of 0.8 milli-Henry in series with the positive feeding to each of the transducers performs a function of division. base unit of sub-speaker for low frequencies 110 operates nominally in the frequency band from 50 Hz to 200 Hz. It should be noted that in each of the speakers described above, the division network is integrated into the room for the associated horn. In addition, it will be noted that the filters that limit the bands 118 and 120 are integrally included in the horns 102 and 104, respectively. In this way, the band limiting device and the associated satellite horn form an integral unit. This provides the added benefit that the interconnect module 14 of Figure 1 can be constituted or simply by appropriately wired power and output plugs. Figure 3a illustrates a second preferred embodiment of the present invention. The home theater surround sound speaker system (surround sound speaker system) 200 of Figure 3a employs components similar to those employed in the surround sound system 100 of Figure 2, and will refer to similar components to using numbers reference from 200 instead of 100. The surrounding sound system 200 of Figure 3a is as described in Figure 2, except that the left-side speaker 202 and the right-side speaker 204 are configured to reproduce signals of difference (L - R) and (R - L), respectively. The positive terminal of the left channel amplifier 212 outputs an amplified left channel signal to the positive terminal of the right-side speaker 202 by a filter 218. The positive terminal of the right channel amplifier 216 outputs a channel signal amplified right connected to the negative terminal of the left-side speaker 202. Singularly, the positive terminal of the amplifier of the right channel 216 outputs an amplified right-channel signal to the positive terminal of the right-side speaker 204 by a filter 220 The positive terminal of the amplifier of the left channel 212 outputs an amplified left channel signal which is connected to the negative terminal of the right-hand speaker 204. These connections effect a difference signal (LR) which is fed to the speaker of the left channel. left side 202 and a difference signal (RL) that is fed to the right side speaker 204.

As described with respect to Figure 1, the left high pass filter 218 and the right high pass filter 220, filter out the low frequency components of the limiting signals applied to the left side horn 202 and the right-side speaker 204, respectively. In applications, where the satellite horns receive difference signals such as feeds, high-pass filtering as described in Figure 2, or difference signals become optional. However, there are two additional benefits to high-pass filtering of difference signals (L-R). First, the physical size of the side speakers may remain small. Second, uncoupling the left and right channel signal gains may cause the difference signal to leak. Bandwidth of the difference signal helps to ensure that the location of the dialogue remains in the center speaker's location, even when the signals on the left and right channels are not exactly the same and dialogue on the difference signal is leaked, by filtering out this leak signal in the primary voice frequency range. In an alternate configuration of the second, preferred embodiment, and reversing the polarity of the difference signals results in a difference signal (L-R) to the right-side speaker 204 and a difference signal (RL) applied to the speaker on the left side 202. Still in another alternate mode, a difference signal (LR) can be applied to both side horns 202 and 204, or a difference signal (R-L) can be applied to both side horns 202 and 204. The polarity The difference signal applied to the side loudspeakers does not materially affect the performance of the system when the difference signal is limited in band, because the lateral boci-ias operate nominally on 1 KHz where the acoustic difference is inaudible. In addition, because the wavelengths of the sound signal in this frequency range are relatively short, small changes in the relative placement of the side horns 202 and 204 will have more of an effect on the way in which the signals they combine in the listening position that the relative polarity of the signals applied to the side speakers. A particular advantage of directing the left side speaker 202 and the right side speaker 204 with the difference signal (either (LR) or (RL)) is that the difference signal removes sound components recorded equally in the left and right channels. , effectively decoupling the reproduction of surrounding ambient sound and dialogue. Considering a system where the left and right channel signals are output to the respective left and right satellite speakers, they can still receive residual vocal energy harmonics in the left and right signals at higher frequencies such as harmonic overtones, which they are heard as sibilant sounds. When these hissing sounds are reproduced by the satellite speakers, the satellite horns provide a directional indication that can result in unnatural breathing of the dialogue and blur the sonic image. The difference signals however eliminates these problems by removing all traces of dialogue energy from the surrounding ambient sound. An additional benefit can be obtained by limiting in band the difference signal that substantially contains only surrounding ambient sound information. The band limitation of the difference signal allows the use of a much smaller satellite horn because the satellite horn only needs to reproduce high frequency acoustic output. In this way, the combination of band limitation and the use of difference signals are successful in decoupling dialogue and environment sound reproduction, which ensures localization of dialogue in the video image while maintaining a consistent ambient sound field. . This decoupling introduces a fundamental difference between the passive system of the present invention and the surrounding active sound decoding systems. The seventh deemed paeivo does not introduce any sonic artifact when dialogue enters and exits within the ambient sound field recorded in the sound track. In this way, a consistent ambient sound field results while the dialog remains located on the video screen. The connections for the center speaker, subwoofer for low frequencies and rear speaker illustrated in Figure 3a, are the same as described with respect to Figure 2. The left channel amplifier 212 outputs an amplified left channel signal which is fed to the positive terminal of the moving coil 214 a of the central speaker 206. The negative terminal of the moving coil 214 a of the central speaker 206 is connected to the negative terminal of the left channel amplifier 212. Similarly, the amplifier of right channel 216 outputs an amplified right channel signal which is fed to the positive terminal of the mobile coil 214b of the central speaker 206. The negative terminal of the mobile coil 214b of the central speaker 206 connects the negative terminal of the a plifier of right channel 216. The left and right channel signals are thus connected in phase with the two mobile coils 214a and 214b of the central speaker 206, such that the output of the central speaker 206 is the left and right sum signals. Again with reference to FIG. 2 (and 3), the left-side speaker 102 (202) and the right-side speaker 104 (204) receive the signal output amplified by the left and right channel amplifiers 112 (212) and 116 (216), respectively. However, the operating bandwidth of side horns 102 (202) and 104 (204) is restricted. The bandwidth of the side horns 102 (202) and 104 (204) in the present invention is limited to a frequency range substantially over the primary frequency range of the voice signals or the dialogue output through the central speaker 106 (206). More particularly, the primary energy in the speech signals is contained in the frequency range of approximately 150 Hz to 1 KHz. Laterale horn 102 (202) and 104 (204) are limited in bandwidth by high-pass filters 118 (218) and 120 (220), respectively, to operate in the frequency range of at least about 1 KHz. Figure 3b illustrates a variation of the second preferred embodiment of the present invention. The home theater surround sound system (surround sound speaker system) 200 * of Figure 3b employs components similar to those used in the surround sound systems 100 and 200 of Figures 2 and 3a, and similar components Figures 2 and 3a will be referred to using identical reference numbers. The surrounding sound system 200 'of Figure 3b is as described in Figure 3a, except that the left side speaker 202 and the right side speaker 204 are configured to produce difference signal (L - ßR) and (R - ßL), respectively. As in Figure 3a, the positive terminal of the left channel amplifier 212 outputs an amplified left channel signal to the pole pointer of the left channel side speaker 202 via a filter 218. The pole position of the right channel amplifier 216 sends an output of an amplified right channel signal connected to the negative terminal of the left-side speaker 202 by an attenuator 270. Similarly, the positive terminal of the amplifier of the right channel 216 outputs an amplified right-channel signal to a positive terminal of the right-side speaker 204 through a filter 220. The pointer terminal of the left-channel amplifier 212 outputs an amplified left-channel signal that is connected to the negative terminal of the right-side speaker 204, via the attenuator 272.

The attenuators 270 and 272 decrease the subtracted signal before feeding to the negative terminals of the respective side horns, 202 and 204. This results in an output (L - ßR) of the left side speaker 202 and (R - ßL) of the right-side speaker 204, where ß is defined as the gain of the attenuators 270 and 272 respectively. The gain ß of the attenuators 270 and 272 preferably have a value between zero and unity. In addition, as will be understood by a person skilled in the art, the gain ß of the attenuators 270 and 272 may be fixed or may be variable according to particular details of the year. In addition, each attenuator 270 and 272 can optionally provide a different gain, such that the attenuator 270 provides a gain ßj. and attenuator 272 provides a β2 gain. A person skilled in the art will readily recognize many different implementations of attenuator 270 and 272 to provide a ß gain. For example, amplifier 270 and 272 can be implemented as resistors or potentiometers, in a relatively simple implementation. In a more complex implementation, attenuators 270 and 272 can be implemented in any of a number of amplifier configurations known to those skilled in the art.

Figure 4a shows a pair of first order high pass networks for implementing high pass filtering in signals that are fed to the left side speaker 102 (202) and the right side speaker 104 (204) of Figures 2 and 3. The left high pass filter 118 (218) and the right high pass filter 120 (220) include capacitors 150 and 152 respectively, connected in series with side horns 102 (202) and 104 (204). This filtering configuration is referred to as a first order high pass filter. Figure 4b illustrates a left high-pass filter 118 (218) and the right high-pass filter 120 (220) implemented as second-order high-pass networks. The capacitors 154 and 156 are connected in series with the positive terminals of the side horns 102 (202) and 104 (204), respectively and the inductors 158 and 160 are connected in shunt through the positive and negative terminals of the side horns 102 (202) and 104 (204). The operation of the high-pass network illustrated in Figures 4a and 4b is well understood by those skilled in the art and will not be explained here. Furthermore it will be recognized by a person skilled in the art that high-pass filters 118 (218) and 120 (220) can be implemented in any of a number of known configurations in the specialty. The use of a passive high-pass filter is easily recognized as a focus to limit in band design. Additionally, it will be recognized by a person with special skill in the specialty that the cutoff frequency may vary according to the particular implementation desired. The limited bandwidth of the signal frequencies range fed to the side horns 102 (202) and 104 (204) removes substantially dialogue location indication from the side horn 102 (202) and 104 (204) , such that the primary dialogue location indication eolo is reproduced by the central speaker 106 (206) which is in proximity to the video image. The limited bandwidth in side horns 102 (202) and 104 (204) forces dialogue location to the location of the center speaker 106, since the center channel becomes the only speaker in the system reproducing the location indication of the fundamental dialogue. The left side speaker 102 (202) and the right side speaker 104 (204) reproduce the upper left and right channel frequency information respectively, which is generally greater than the primary speech frequency range. The side horns 102 (202) and 104 (204) in this manner help in providing an increased sense of spacing and in altering the location of the speech eonidoe. It has been shown through numerous eetudioe in acoustics of concert halls, that a sense of spaciousness correlates with the presence of lateral reflections. That is, the spaciousness correlates with the energy that arrives at the listening point from the sides of the listening space. Locating side horns 102 (202) and 104 (204) on the sides of the listening room and orienting the main axis of radiation vertically upwards allows side horns 102 (202) and 104 (204) to generate side energy eignificante in the hearing position, thus improving the spaciousness.

Additionally, because the side speakers 102 (202) and 104 (204) of the present invention are limited in band to significantly reduce indication of location of the dialogue, they can be moved further to the sides of the listener than the traditional speakers. Even more, because the side horns 102 (202) and 104 (204) are limited in band, the increased displacement does not cause distracting sound images on the sides of the listener, as would occur if the full-range audio speakers were placed at such sites. This allows the side speakers to be placed for maximum space without generating distracting sound images.

An additional benefit to limiting band side horns is that their physical size may be relatively small. The band limitation of the side speakers at about one KHz has a very different configuration than the audio / sub-speaker systems for typical low frequencies. In most satellite / eub-speaker systems for low frequencies, the satellite speakers operate over a much larger frequency range, typically at a value as low as 150 Hz. These horns are therefore required to be much larger than the side horns of the present invention, in order to generate sufficient energy at these lower frequencies. In the present invention, the side horns reproduce a much more restricted range of frequencies. Figure 5a shows a central speaker 106 (206) comprising a dual mobile coil 114a and 114b (214a and 214b) and a single transducer 115 (215) as illustrated in Figures 2 and 3. The amplified left channel signal is applies to the moving coil 114a (214a) and the amplified right channel signal is applied to the moving coil 114a (214b). In this configuration, the left and right channel signals are added electromagnetically inside the transducer 115 (215).

Another particular advantage of this invention can be demonstrated with particular regard to Figure 5a. In Figure 5a, the left and right channel signals that are outputted by respective amplifiers 112 and 116 each individually applied to the mobile coils 114a and 114b of the transducer 115 to electromagnetically create the sum signal (L + R). The central horn of Figure 5a in this way generates the sum signal passively without need by a resistor divider network that can consume energy and contribute cost in complexity to the system. These energy savings are particularly relevant when the invention described herein has the left and right channel signal from a relatively low power amplifier source such as a typical stereo television set or a portable stereo type acoustic box with single frequency resonance. . The rightmost left sum inside the horn itself avoids the requirement for additional parts and their associated costs. In an alternate center channel configuration illustrated in Figure 5b, the left and right channel signals direct individual left and right transducers 117 and 119. The left channel amplified signal directs the mobile coil 114a (214a) which in turn directs the left transducer 117. The right channel amplified signal directs the voice coil 114b (214b) which at the same time directs the transducer 119. It should be noted that in the configuration of Figure 5b, the transducers 117 and 119 should be located in relatively close proximity , such that the output of both transducers 117 and 119 acoustically sum over a possible maximum frequency range. Effective addition of acoustics requires that the two transducers be located within approximately a quarter of a wavelength between them. This proximity is practically not achieved over the entire range of audible frequencies. At higher frequencies, some comb filtering will occur in the combined acoustic output from the two transducers. In the case of a monophonic signal, because both transducers radiate the same signal and move in space, the difference in the resulting path length between the listening location and each transducer becomes an appreciable fraction of a wavelength or multiple wavelengths at higher frequencies . Minimizing spacing between the two elements, in this way reduces the amount of comb filtering that occurs. Figure 6 illustrates two alternate modes for obtaining the difference signal (L-R) of the rear speaker 108 (208) of Figures 2 and 3. The difference signal typically contains surround and surround sound information. Figure 6a illustrates a circuit diagram for a preferred embodiment for obtaining the signal (L-R) in a passive system. The left channel amplifier 112 (212) outputs an amplified left channel signal which is fed to the positive terminal of the voice coil 130 of the rear speaker 108 (208), and a right amplifier 116 (216) is sent from outputting an amplified right channel signal to the negative terminal of the voice coil 130. The rear speaker 108 (208) thus outputs audio in response to the difference between the left and right channel signal (L-R) through transducer 134. Figure 6b illustrates a circuit diagram for an alternate configuration to obtain a difference signal (L-R). Rear horn 108 includes dual mobile coils 132a and 132b. The mobile coil 132a receives on its positive terminal the left channel signal amplified from the left channel amplifier 112 (212). The negative terminal of the moving coil 132a is connected to the negative terminal of the left channel amplifier 112 (212). The mobile coil 132b receives the amplified right channel signal from the right channel amplifier 116 (216) at its negative terminal and the positive terminal of the mobile coil 132b is connected to the negative terminal of the right channel amplifier 116 (216). In this way, this configuration inverts the polarity of the connection in such a way that the transducer 134 outputs a resultant signal (L -R). Figure 7 illustrates a third preferred embodiment of the present invention wherein a surround sound speaker system for home theater 300 employs low level signal processing before amplification by amplifier 302 and amplifier 304. Poeitive signal of left channel 306 and positive signal of right channel 308, supply summation amplifier 310, any number of sum amplifiers for electronically adding signals of which are known in the art. The output of the summing amplifier 310 provides a summing signal (L + R) which in turn feeds the power amplifier 302. The positive output of the amplifier 302 supplies an amplified signal (L + R) to the positive terminal of the speaker 312. The negative terminal of the central speaker 312 connects to the negative terminal of the amplifier 302. The positive terminal of the power amplifier 302 also outputs an impulse signal to the positive terminal of the sub-speaker for low frequencies 314. The sub-speaker for low frequencies 314 comprises a simple transducer and moving coil. Similar to the center speaker 312, because the signal (L + R) directs the eub-speaker for low frequencies 314, the sub-speaker for low frequencies 314 only requires a simple voice coil and transducer to output the portions of Low frequency of the signals left and right. It will be recognized by a person skilled in the art that alternate sub-speaker configurations for particular low frequencies may be employed with the present invention with minimal effect on the operation of the system. The perimeter sound system 300 also actively provides a difference signal. Before amplification by amplifier 304, the left channel positive signal 308 and the right channel positive signal 306 feed up to the difference amplifier 316. The difference amplifier output 316 outputs a less right left difference signal (L-R). This difference signal (L-R) is fed to the power amplifier 304. The pole output of the power amplifier 304, at the same time directs the positive terminal of the rear spe 318. The negative terminal of the rear spe 318 is connected to the negative terminal of the power amplifier 304. In this way, the signal output (L-R) by the amplifier 304 directs the rear spe 318.

The positive terminal of the amplifier 304 also outputs an impulse signal to the positive terminal of the left side speaker 320 through the high pass filter 324. The negative terminal of the left side speaker 320 is connected to the negative terminal of the power amplifier 304. Similarly, the positive terminal of the power amplifier 304 outputs an impulse signal to the negative terminal of the right side speaker 322 through the high pass filter 326. The positive terminal of the side speaker right 322 is connected to the negative terminal of the power amplifier 304. The connection to the left-side speaker 320 provides a re-pulsing (L-R) signal to the speaker. The connection to the right-side speaker 322 provides a resulting signal (R-L) to the speaker. The polarities of the signals applied to each of the left side speakers 320, right side horns 322 and the rear speaker 318, can be reversed and the system will provide the same effect. All possible permutations of connections of relative polarity of the difference signal to the two side speakers and the rear speaker are also acceptable and provide satifactory results. High-pass filter 324 and 326 operate as described above with respect to Figures 2 and 3.

This configuration in itself has an energized variation in particular, wherein the interconnection module can include an internal amplifier for the electric power signals and output the amplified electrical signals to direct the respective horns. A particularly advantageous feature of an internally energized interconnection module would be that there are options to asymmetrically expand the output signals, so that speakers that require more power to operate satisfactorily receive higher power supply signals. For example, the addition signal feed to the center and bass horns can be outputted at a much higher energy rating than the difference signal that is output to the satellite horns and back environment. This approach provides the high energy to direct the bass and front speakers while leaving less but sufficient power to direct the side and rear speakers. For example, instead of a 10 watt stereo amplifier configuration plus 10 watts, an 18 watt amp configuration plus 2 watts can be used to more efficiently use the available energy.

Figure 8 illustrates a fourth preferred embodiment of the present invention. The surround sound system for home theater (surround sound system) 400 of Figure 8 employs components similar to those used in a surround sound system 100 of Figure 2, and similar components will be referred to using reference numbers from 400 instead of 100. The surround sound system 400 of Figure 8 is similarly configured to Figure 2, except that it receives and outputs a monophonic signal instead of the signals of left and right component channels. a signal in stereo. The perimeter sound system 400 includes the left side satellite horn 402 (the left side or satellite horn) of the right side satellite horn 404 (right side speaker or satellite) central horn 406, surround or rear horn 408 and horn sub-speaker for low frequencies 410. The amplifier 412 receives a monophonic signal and outputs an amplified monophonic signal which is fed to the positive terminal of the moving coil 414 of the central speaker 406. The negative terminal of the moving coil 414 of the central speaker 406 connects the negative terminal of the amplifier 414. The moving coil 414 of the central speaker 406 directs the transducer 415 to output sound from the central speaker 406. The positive terminal of the amplifier 412 also outputs an amplified signal to the amplifier. the positive terminal of the left side speaker 402, through the filter 418 and the right side speaker 404 through the filter 420. The left side speaker 402 and the right side speaker 404 are bandlimited to only reproduce higher frequencies, as illustrated using the left high pass filter 418 and the right high pass filter 420, which operate as previously described here. The perimeter sound system 400 also includes a rear speaker 408 that receives the amplified output from the amplifier 412. The rear speaker 408 also includes a potentiometer that provides a ground path for the amplified signal that is fed to the rear speaker 408. The potentiometer 409 allows adjustment of the acoustic output of the rear speaker with respect to the output of the other speakers in the system. The rear speaker 408 is preferably adjusted such that the sound pressure level occurs at the listener's site, which is below that produced by the front speaker 415 at that site. This causes the listener to perceive dialogue from the front stage, according to the precedence effect of the sound reproduction. That is, as between two similar sounds, the human hearing process interprets the direction in which a sound arrives first as the direction from which both sounds come. Due to the psychoacoustic phenomena known as intensity-time compensation, sounds of higher levels are perceived by the listener, who arrive earlier. Therefore, by varying the output of the rear speaker 408 to a level sufficiently lower than that of the front speaker 406, the sonic image is perceived as forward, but the acoustic energy of the rear speaker 408 provides additional acoustic information. The hearing process interprets this additional information as ambient or perimeter sound. It will also be recognized that level adjustment can be achieved by any of a number of approaches known to those skilled in the art. In addition, because the embodiments of Figure 8 use only one expansion channel, compared to two for a stereo configuration, the listener will typically increase the total system volume to achieve the desired sound pressure level. As an extension to the fourth embodiment illustrated in Figure 8, a similar result can be achieved by applying a monophonic signal to the amplifier 212 of Figure 3a, without power signal applied to the positive power of the amplifier 216. This assembly similarly provides an effect of perimetric sound based on a monophonic power signal and provides flexibility to a perimetric sound system configured in Figure 3a, to use as well as with stereo and monophonic signals. A particularly convenient feature of most surround sound systems is the ease of installation and operation to avoid discouraging use by non-technical consumers. This invention solves most of the installation difficulties by providing a home theater interconnection module 14, with connection plugs that confine the system to one and only a possible set of speaker connections for the particular modes, wherein the signal of difference (L - R) are output to the side speakers. Figure 9 is a wiring diagram showing the interconnection plugs with the interconnection module 14 of Figure 1, and will be described with reference to the components discussed in Figure 1. The interconnection module 14 includes 4 power supply plugs. terminal 30 for receiving the left and right component channel signals, which are fed to the interconnection module 14 of the television 12. The left and right channel signals are received by a fourth conductor cable terminating in a fourth terminal connector, which corresponds appropriately with the four-terminal power plug 30. The negative feeds for the left and right channels are linked together within the interconnect module 14 to provide a common ground signal for each of the power and output connections. The output to the central speaker 20 (of Figure 1) is provided by a three-terminal output plug 32. The three terminals of the output plug 32 provide ealidae comprising the left channel signal, the right channel signal and a common ground signal. A second sub-speaker output socket for low frequencies of three terminals 34 provides output signals similar to the sub-speaker for low frequencies 18. The sub-speaker output plug for low frequencies 34 similarly provides the left channel signal, the right channel signal and a common ground signal at the respective terminals. A trio of two-way outlets 36a, 36b and 36c provides the left channel signal in one terminal and the right channel signal in the other terminal. Each of these plugs interconnects with cables that in turn are connected to one of the rear speaker 26, the left satellite horn 22 and the right satellite horn 24. The resulting signal that is provided from those speakers is the left difference signal less right. The configuration of the interconnection module 14, in this way is particularly adapted to the preferred embodiment illustrated in Figure 3a where the left satellite horn 22, the right satellite horn 24 and the rear horn 26, have the difference signals as feeds. It will be recognized by a person skilled in the art that the output jacks 36a, 36b, and 36c are interchangeable because each of the outputs are their sub-identically identical signals. One of the particularly advantageous features of the interconnect module 14 is that the output plug for central speaker 32 and the sub-speaker output plug for low frequencies 34 can be identical sockets that send identical signal outputs on each terminal. In this way, during installation, the operator can install the seventh in one configuration. The operator can not connect the cable connector (not shown) for the center speaker 20 or the pole speaker 26 to one of the output sockets 36a, 36b or 36c. Similarly, the output plugs 36a, 36b and 36c result in identical signals on each terminal. That is, all output (and input) sockets similarly provide (receive) the same signals. Similarly, the operator can not connect the cable connector for the rear satellite speakers to the central speaker output socket 32 or sub-speaker output socket for low frequencies 34. The operator can only connect the cable connector to one of the plugs that output the appropriate signal (s) for a particular speaker. In addition, the particular operation of this invention facilitates configuring the interconnect module 14 to allow ease of installation. Another particularly advantageous feature of the present invention is that the interconnect module 14 is particularly adaptable to 2, 3 and 4 standard conductor cables that facilitate low cost manufacturing due to the use of readily available parts. An improvement to any surround sound system for home theater results in reducing the number of components. One approach to component reduction is to consolidate components when possible. For example, with reference to Figure 1, the interconnection module 14 and sub-loudspeaker for low frequencies 18, can logically be consolidated into a single component. Figure 10 illustrates this alternate configuration for the surround sound speaker system for home theater 10 of Figure 1. The surround sound speaker system for home theater (perimetric sound system) 10 'of Figure 10 is available similarly as in Figure 1 and the reference numerals in Figure 10 refer to similar components of Figure 1. As can be seen in Figure 10, the television 12 outputs an audio signal to the low subwoofer. integral low-frequency loudspeaker and interconnection module 40 (integral bass unit) the integral low unit 40 performs the combined function of the interconnection module 14 and sub-loudspeaker for low frequencies 18 of Figure 1. The interconnection module 14 has been Built-in speaker housing for low sub-speaker for low frequencies, in order to reduce the number of parts and wiring requirements and to further facilitate installation. The integral bass unit 40 includes an interconnecting portion for distributing the appropriate signals to each of the front center horn 20, the left satellite horn 22, the right satellite horn 24 and rear ambient horn 26. The integral bass unit 40, also includes a sub-speaker for low frequencies, wired directly to the interconnection circuits housed in the integral bass unit 40. In this way, the system requires one less cable (between the interconnection module and the sub-bass speaker). loudspeaker for low frequencies) and also requires an individual component or autosue entante menoe (the interconnection module). Figure 11 illustrates an exemplary perspective view of the integral bass unit 40. The integral bass unit 40 includes an interconnection module 42 having available power and output sockets for receiving the input audio signal and distributing the left eelee , right and difference to the appropriate speakers. The interconnect module 42 includes a four-terminal power plug 44 for receiving via a fourth conductor wire, the left and right channel. The interconnect module 42 also includes an output plug for three-terminal central speaker 46 and a trio of two-terminal outlet plugs 48a, 48b and 48c. The interconnection module 42 is similarly arranged to the interconnection module 14 of Fig. 9 and the principles discussed with respect to Fig. 9 equally apply to Fig. 11. A particular difference between the interconnection module 42 of Fig. 12 and the module interconnection 14 of Figure 9 is that because the interconnect module 42 is integrally housed with the low eub-speaker speaker for low frequency, the interconnect module 42 does not require a sub-speaker output plug for low frequencies (as the interconnection module 14 of Figure 9). The left channel signal, the right channel signal and the common ground signal are fed directly into the divider network of the integral low frequency eub-speaker unit 40. A particular advantage of an additional alternative embodiment of this invention solves the problem common of many typical consumer audiences that do not lead to an easy wiring of the interconnection module with the bocinae of poeternal environment and reelectivae satellite. Typically, wiring surround sound system for home theater, requires passing wires over the walls around the sides and back of the room or drilling through the floor and passing cable under the auditorium and re-entering the auditorium in the respective place of the speakers. This invention particularly leads to a communications system for surround sound speakers in home theater, wireless 50, as illustrated in Figure 13. A television 51 provides the left and right channels and a stereo audio signal to the interconnect module 52 The interconnection module 52 distributes the left and right channel signals with the appropriate horn so as to effect the desired system. In the embodiment illustrated in Figure 13, the interconnect module 52 is wired directly to the television 51, the front center speaker 54 and sub-speaker for low frequencies 70. In order to transmit the audio signals to the appropriate speakers, the Interconnect module 52 also includes a transmitter 56 for sending an audio signal to the left satellite horn 64, right satellite horn 66, and the rear environment horn 68. Each of the speakers 64, 66 and 68 includes a receiver 56 ' to receive the output signal that is broadcast by the transmitter of the interconnection module 52. The receiver 56 'receives the tranced signal and transports to another key or other tone the signal within a suitable audio signal for its respective horn. It will be understood by a person skilled in the art that the receiver 56 'can be configured to output the transferred signal to a front amplifier for application to the speakers. The transmitter 56 and the receiver 56 'preferably operate on a single channel. In order to use a single channel receiver / transmitter configuration, the interconnection module 52 preferably outputs only one audio signal to each speaker. In order to achieve this convenient configuration, the surround sound system for home theater 300 of Figure 7 would be the preferred embodiment for implementing the wireless surround sound system 50 of Figure 13. In this embodiment, the interconnection module 52 performs additions and subtractions of active signal (as described with respect to Figure 7) to generate the difference and sum signals, before transmission to the respective speakers. This configuration will limit the wireless system to single channel communication, instead of multi-channel communication. In addition, it will be recognized by a person skilled in the art, since the left channel speaker 320, the right channel speaker 322 and the rear speaker 318 are directed subetanially by substantially identical difference signals, the interconnect module 52 can use a transmitter (56, for example) to transmit an excitation audio signal to each of the speakers, thereby resulting in sub-cost savings. It will also be recognized by a person skilled in the art that recipients and transmitters may be configured to wirelessly connect components that have been described here as direct cabling. From the foregoing, it can be seen that this invention solves the various problems encountered in the prior art and satisfies the various objects of the invention. This invention of this way, provides a system of surround sound speakers for effective, inexpensive, easy to install home theater. The front, rear, left, right and bottom speakers provide the desired sound outputs, in response to application and the sum and difference signals properties that result from the combination of the left and right channel signals of a stereo signal. The sum and difference signals provide the desired dialogue and ambience audio in the appropriate speaker. Although the invention has been described with particular reference to certain preferred embodiments thereof, variations and modifications may be made within the spirit and scope of the following claims. What is claimed:

Claims (21)

1. CLAIMS 1.- A boomroom for playing a monophonic audio signal generated by an audio signal source, characterized in that it comprises: a front speaker to provide an acoustic output in response to the monophonic audio signal; a rear speaker to provide an acoustic output in response to the monophonic audio signal; means for filtering the monophonic audio signal that is fed to the left satellite horn, to substantially eliminate acoustic frequencies from low and medium ranges; a left satellite horn to provide an euenetanically acoustic output eolo in reepueeta to the filtered monophonic audio signal; means for filtering the monophonic audio feed to the right satellite horn, to substantially eliminate acoustic frequencies from low and medium ranges; a right satellite horn to provide an acoustic output subetanially eolo in reepueeta to the filtered monophonic audio signal; and a speaker below to provide low frequency acoustic output in response to the monophonic audio signal.
2. 2. - The apparatus according to claim 1, characterized in that it further comprises an amplifier for receiving and amplifying the monophonic audio signals before application to the rearview loudspeakers.
3. 3. - The apparatus according to claim 1, characterized in that the means for filtering power to the left and right satellite horns are substantially identical and also comprise first order filters.
4. 4. The apparatus according to claim 1, characterized in that the means for filtering power to the left and right satellite horns are substantially identical and also comprise second order filters.
5. 5. - The apparatus according to claim 1, characterized in that it further comprises: a left high pass filter to pass to the left satellite horn, audio frequencies of the monophonic audio signal, generally greater than a predetermined threshold frequency; and a right high pass filter to pass to the right satellite horn audio frequencies of the monophonic audio signal generally greater than a predetermined threshold frequency.
6. 6. - The apparatus according to claim 5, characterized in that the left and right high pass filters are substantially identical and further comprise a capacitor in series with a positive feed terminal of the audio signal applied to the satellite horn.
7. 7. - The apparatus according to claim 5, characterized in that the left and right high pass filters are substantially identical and further comprise: a capacitor in series with the positive terminal of each satellite horn; an inductor in derivation through the positive and negative signals of each satellite horn.
8. 8.- Speaker system for reproducing a stereo audio signal generated by an audio signal source, characterized in that it comprises: a front speaker to provide an acoustic output in response to a power signal (L + R), where L is a left channel signal of the stereo signal and R is a right channel signal of the stereophonic audio signal; a pole speaker to provide an acoustic output in response to a power signal defined as a difference between the left and right channels; means for forming a variable difference signal defined as the difference between the left signal ((L - ßR) or (R - βL)), wherein ß is defined as a gain factor for the respective signal; means for filtering the variable difference signal that is fed to the left satellite horn, to substantially eliminate low and mid-range acoustic frequencies; a left satellite horn to provide an acoustic output substantially only in response to the variable difference signal; means for filtering the variable difference signal that is fed to the right satellite horn, to eliminate substantially low and medium range acoustic frequencies; a right satellite speaker to provide an acoustic output eubertially only in response to the variable difference signal; and a lower speaker to provide low frequency acoustic output in response to the power signal (L + L).
9. 9. The apparatus according to claim 8, characterized in that it also comprises at least one amplifier for receiving and attenuating the left and right channel stereophonic audio signals subtracted from the variable difference signals, the amplifier gain ß has a value variable from zero to unity.
10. 10. The apparatus according to claim 8, characterized in that the left satellite horn receives a first variable difference signal that is defined as one of (L - ßR) or (R - ßL)) and the right satellite horn receives the another variable difference signal of (L - ßR) or (R - ßL)).
11. 11. - The apparatus according to claim 8, characterized in that the means for filtering power to the left and right satellite horns are eubstantially identical and also comprise first order filters.
12. 12. - The apparatus according to claim 8, characterized in that the means to filter power to the left and right satellite speakers are substantially identical and also comprise second order filters.
13. 13. - The apparatus according to claim 8, characterized in that it further comprises: a left high pass filter, to filter the variable difference signal that is fed to the left satellite horn; and a high-right filter to filter the variable difference signal that feeds the right satellite horn.
14. 14. The apparatus according to claim 8, characterized in that ß can be varied between zero and unity.
15. 15. - A speaker system for reproducing an etereophonic audio signal generated by an audio signal source, and associated with an accompanying video signal, characterized in that it comprises: a signal pre-processor to generate summation output signals R + L) and difference ((R - ßLL) or (L - ß2R)), based on a power signal L and R, where L is a left channel signal of the stereophonic signal and R ee a channel signal right of the stereophonic signal and _. and ß2 are defined as gains for the respective subtracted signals; a first horn to provide an acoustic output in response to the summation output signal; first means for filtering the difference output signal to eliminate eubertially and low frequency acoustic frequencies; a second horn for providing an acoustic output subetanially eolo in reepueeta to the first filtered difference output signal; second means for filtering the difference output signal to substantially eliminate acoustic frequencies from low and medium ranges; a third horn to provide an acoustic output substantially only in response to the second signal of difference of filtered difference; and a fourth horn to provide an acoustic output in response to the difference signal.
16. 16. - The apparatus according to claim 15, characterized in that it further comprises a fifth horn to provide low frequency acoustic output in response to the sum output signal.
17. 17. - The apparatus according to claim 15, characterized in that it further comprises a pair of amplifiers having gains x and ß3 respectively to receive and amplify the left and right channel feed signals, respectively, to produce ßxL and ß2R signals before sub-traction to form the signs of difference.
18. 18. - The apparatus according to claim 15, characterized in that ßj. and ß2 are the same.
19. 19. The apparatus according to claim 18, characterized in that _._ and ß2 can be varied between zero and unity.
20. 20. The apparatus according to claim 15, characterized in that &; _ and ß2 each can be varied independently.
21. 21. The apparatus according to claim 15, characterized in that first and second means for filtering are subetancialmente identical and also comprise a filter of first order. SUMMARY pig THE INVENTION An apparatus for realistically reproducing sound, particularly for sound based on a stereophonic signal that has dialogue and effects and associated with an accompanying video image. The apparatus includes a front speaker located in proximity to the video image to provide acoustic output based on a sum signal of the left and right component channels (L + R) of the audio signal. A rear speaker located at the back of the viewing area provides acoustic output based on a difference signal (L - R) or (R - L) between the left and right channels. The left and right speakers are located on the respective left and right sides of the viewing area. The left channel speakers reproduce in one mode, the respective left and right channels of the audio signal and in a second mode reproduce a difference signal (L - ßR) or (R - ßL)), where ß ee a gain which can vary can be a fixed value between zero and unity. The output to the left and right speakers is band-limited to substantially filter the frequency components below a predetermined threshold. A lower speaker can also be provided to output the low frequency components of a sum signal (L + R). The euma signal (L + R) that is fed to the front speaker helps in locating dialogue in the video image. The signal of difference (L - ßR) or (R - ßL)) eubstantially removes dialogue sound so that the output of the side and rear speakers, primarily comprises sonic environment and surround sound effects or perimetric. The band feed from the left and right speakers also helps in locating dialogue in the video image. Alternatively, even in another embodiment, a monophonic signal may be applied at least to one modality of the seventh to allow production of a peripherally enhanced perimetric effect.