JP2008053902A - Acoustic reproduction system and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform multichannel surround reproduction for achieving a sound field giving more presence by improving deficiency in volume of low-pitched sound, continuity of a sound image by low-pitched sound, and the like. <P>SOLUTION: Out of muti-channel sources S1-SN and Ssw, the low frequency effect signal Ssw of a surround channel is reproduced by a sub-woofer speaker, harmonics of integer times of the low level effect signal Ssw is generated at a harmonic generating section HMC, that harmonic component SHM and the channel signals S1-SN of respective main channels are compounded at compounding sections MIX1-MIXN, and a correction channel as the result of compounding is supplied to a main speaker and reproduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an audio reproduction system and an audio reproduction method for performing multichannel surround reproduction.

  This type of sound reproduction system is a multi-channel source (multiple channels) standardized in information recording media such as DVD (Digital Versatile Disc) audio and Super Audio CD (Compact Disc), BS digital broadcasting, terrestrial digital broadcasting, and the like. Signal) is reproduced by multi-channel surround playback with a plurality of speakers, thereby realizing a realistic sound field.

  As shown schematically in FIG. 1 (a), the most basic 2.1-channel sound reproduction system includes three speakers, left and right front speakers FL and FR, and a subwoofer speaker SW. Among the sources, the 0.1 channel signal Ssw limited to the low frequency band is reproduced by the subwoofer speaker SW, and the remaining left and right channel signals SFL and SFR are converted to the left and right front speakers FL, A sound field that provides a sense of realism can be realized by playing each of them independently using FR.

  In addition, a sound reproduction system with more than 2.1 channels is also known. As schematically shown in FIG. 1B, for example, in a 5.1 channel sound reproduction system, the left and right front speakers FL, FR and Six speakers, rear speakers RL and RR, a center speaker C, and a subwoofer speaker SW, are used for subwoofer, which is a 0.1 channel channel signal Ssw limited to a low frequency band among multichannel sources. By reproducing the bass sound with the speaker SW, the remaining five channel signals SFL, SFR, SRL, SRR, Sc are independently reproduced with the left and right front speakers FL, FR, rear speakers RL, RR and the center speaker C, respectively. Realize a realistic sound field.

  As described above, in the sound reproduction system that performs multi-channel surround reproduction, the sub-woofer 0.1 channel is further added to the total number N of the front speaker, rear speaker, and center speaker. Low channel effect (LFE: Low Frequency Effet) is achieved by playing a low-frequency sound on a 0.1-channel channel signal, which is called 1 channel, which is limited to the low frequency band, using a subwoofer speaker. It is supposed to realize the sound field that can be.

  In addition, a sound reproduction system that performs multi-channel surround reproduction is also provided in a passenger compartment of an automobile or the like, and it has become possible to enjoy music and the like that provide a sense of reality in the passenger compartment.

  For example, when a 5.1 channel sound reproduction system is provided in a passenger compartment of an automobile or the like, generally, as shown schematically in FIG. A left front speaker FL and a right front speaker FR are installed on both sides of the seat, a left rear speaker RL and a right rear speaker RR are installed on both sides of the rear seat, and a subwoofer speaker SW is installed behind the rear seat (on the trunk side of the car). 5.1 channel signal Sc, SFL, SFR, SRL, SRR, Ssw is supplied from the signal source provided in the set AU and multi-channel surround reproduction is performed, thereby realizing a sound field with a sense of presence. To do.

  By the way, in the conventional sound reproduction system used in a restricted place such as the above-mentioned vehicle interior, the lowest reproducible frequency (low frequency cut-off frequency) is relatively high compared with the subwoofer speaker SW (for example, Small speakers) may be installed as the center speaker C, the left and right front speakers FL, FR, and the left and right rear speakers RL, RR.

  In such a case, the bass sound is not emitted from the speakers C, FL, FR, RL, and RR, and the bass sound is emitted exclusively from the subwoofer speaker SW installed behind the passenger, so that the passenger who is the listener To create a sound field with a sense of realism, such as giving the user the impression that sound can be heard from an unnatural place, or lacking the volume of the bass itself, causing the connection of the sound image due to the bass to be interrupted There was a case that could not be.

  The present invention has been made in view of such a conventional problem, and in the case of multi-channel surround reproduction, it is possible to obtain a more realistic feeling by improving the low volume of bass and improving the connection of sound images due to the bass. An object of the present invention is to provide a sound reproduction system that realizes a sound field.

  According to the first aspect of the present invention, there is provided an acoustic reproduction system for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source, and a low surround channel supplied to the subwoofer speaker. Harmonic generation means for generating a harmonic of a band effect signal; and synthesis means for generating a correction channel signal by combining the harmonic component and the channel signal of the main channel and supplying the correction channel signal to the main speaker. It is characterized by that.

  According to a second aspect of the present invention, there is provided an acoustic reproduction system for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source, wherein the surround channel supplied to the subwoofer speaker is low. Harmonic generation means for generating harmonics of a band effect signal and extracting adjacent harmonics within the reproducible frequency band of the main speaker from the generated harmonics, and the harmonic generation And a synthesizing unit that synthesizes adjacent harmonic components extracted by the means and the channel signal of the main channel to generate a correction channel signal and supplies the correction channel signal to the main speaker.

According to a third aspect of the present invention, in the sound reproduction system according to the first or second aspect, the synthesizing unit further includes a level adjusting unit that amplifies the harmonic component for each channel,
The corrected channel signal is generated by synthesizing the amplified harmonic component and the channel signal of the main channel.

  A preferred embodiment of the present invention will be described with reference to FIG. FIG. 2A is a block diagram showing the configuration of the sound reproduction system of the present embodiment, and FIG. 2B is an explanatory diagram for explaining the function.

  The sound reproduction system 1 of the present embodiment shown in FIG. 2A includes a harmonic generation unit HMC and a plurality of N (N ≧ 2) synthesis units MIX1 to MIXN, and is a signal source not shown. In addition to the most basic configuration that performs multi-channel surround playback based on a 2.1-channel multi-channel source supplied from, a configuration that performs multi-channel surround playback based on a multi-channel source that has more channels than 2.1 channels It is possible to.

  That is, a 2.1-channel channel signal consisting of a 0.1-channel channel signal (hereinafter referred to as a “low-frequency effect signal”) Ssw limited to the low frequency band and the left and right channel signal signals S 1 and S 2. When multi-channel surround reproduction is performed based on a multi-channel source, at least a harmonic generation unit HMC and two (N = 2) synthesis units MIX1, MIX2 are provided.

  N.sub.1 comprising 0.1 channel low band effect signal Ssw limited to the low frequency band and the remaining N (N> 2) channel signals S1 to SN. When performing multi-channel surround reproduction based on a single-channel multi-channel source, it is configured to include at least a harmonic generation unit HMC and N (N> 2) synthesis units MIX1 to MIXN.

  For convenience of explanation, N.I. Of one channel, a 0.1-channel speaker for reproducing a low-frequency effect (LFE) sound is called a “subwoofer speaker”. Further, the remaining N-channel speakers (center speakers, speakers provided on the front left and right of the listener, and speakers provided on the left and right of the listener) are collectively referred to as “main speakers”. Further, 0.1 channel is referred to as “surround channel”, and the remaining N channels are collectively referred to as “main channel”.

  In FIG. 2A, the harmonic generation unit HMC is formed of an electronic circuit having a nonlinear input / output transfer function. Then, the low-frequency effect signal Ssw supplied to the subwoofer speaker is input, harmonics having a frequency that is an integral multiple of the low-frequency effect signal Ssw are generated by a non-linear input / output transfer function, and the generated harmonics Two adjacent harmonic components SHM that are within the range of the reproducible frequency band of the main speaker are extracted and output.

  That is, if the frequency band BF of the low-frequency effect signal Ssw is a signal that is band-limited to a range of frequencies fa to fb (for example, band-limited to 20 Hz to 120 Hz), the harmonic generation unit HMC 2nd harmonic of frequency band of 2 × fa to 2 × fb, 3rd harmonic of frequency band of 3 × fa to 3 × fb, 4th harmonic of frequency band of 4 × fa to 4 × fb, etc. A harmonic is generated, and from the generated harmonics, the second harmonic and the third harmonic, or the third harmonic within the range of the reproducible frequency band of the main speaker as the harmonic component SHM. Adjacent harmonics such as fourth harmonics are extracted and output.

  More generally, with reference to FIG. 2 (b), the harmonic generation unit HMC is adjacent to the low frequency effect signal Ssw of the frequency band BF within the range of the reproducible frequency band of the main speaker. An n-order harmonic Ssw (n) and an n + 1-order harmonic Ssw (n + 1) are generated, and the two adjacent n-order harmonics Ssw (n) and n + 1 are expressed by the following equation (1). The second harmonic Ssw (n + 1) is output as the harmonic component SHM.

  The synthesizing units MIX1 to MIXN synthesize the channel signals S1 to SN and the harmonic components SHM of the main channels, and the correction channel signal SMIX1 which is a synthesis result as represented by the following equations (2a) and (2b). ~ SMIXN is output.

  Then, the sound reproduction system 1 of the present embodiment transfers the low-frequency effect signal Ssw to the subwoofer speaker side of the surround channel and supplies the correction channel signals SMIX1 to SMIXN to the main speaker side of the main channel, thereby Play surround sound.

  According to the sound reproduction system 1 having such a configuration, the following effects can be obtained.

  First, in the harmonic generation unit HMC, the adjacent n-order harmonic Ssw (n) and n + 1-order harmonic Ssw (within the range of the reproducible frequency band of the main speaker from the low-frequency effect signal Ssw of the frequency band BF. n + 1) is generated, and in the combining units MIX1 to MIXN, the channel signals S1 to SN of the main channel and the harmonic component SHM are combined to generate correction channel signals SMIX1 to SMIXN. The

  Therefore, in each main speaker, in addition to reproducing the sound of the channel signals S1 to SN of each main channel, the sound of the harmonic component SHM, that is, the adjacent nth harmonic Ssw (n) and n + 1st harmonic The sound of the wave Ssw (n + 1) is reproduced.

  Here, the reproduced sound of both the n-order harmonic Ssw (n) and the n + 1-order harmonic Ssw (n + 1) is different from the bass reproduced by the subwoofer speaker based on the low-frequency effect signal Ssw. The sound has a frequency that is an integer multiple higher than the low-frequency effect signal Ssw, and is reproduced by the main speaker having a higher reproducible frequency band than the subwoofer speaker.

  Furthermore, when both reproduced sounds are inputted from the listener's ear and reach the brain, humans have the auditory characteristic that the difference component of the frequency of the reproduced sounds is felt most strongly. It is possible to have the same feeling as you listened.

  Thus, according to the sound reproduction system 1 of the present embodiment, the harmonic component (adjacent harmonics) SHM that can be reproduced by the main speaker is obtained from the low-frequency effect signal Ssw that cannot be reproduced by the main speaker. Since it is generated, synthesized with the channel signals S1 to SN of the main channel and supplied to the main speaker for reproduction, the reproduction of the main channel and the low tone similar to that reproduced based on the low frequency effect signal Ssw are generated. Can be heard by listeners. Further, the low sound volume reproduced by the subwoofer speaker based on the low frequency effect signal Ssw and the low sound reproduced by the main speaker and felt by the listener can improve the low volume of the low sound. The connection of sound images can be improved, and a sound field with a more realistic feeling can be realized.

  In the embodiment described above, when the multichannel sources S1 to SN and Ssw supplied from the sound source are analog signals, the harmonic generation unit HMC and the synthesis units MIX1 to MIXN may be formed by analog circuits. If the multichannel sources S1 to SN and Ssw supplied from the sound source are digital signals, the harmonic generation unit HMC and the synthesis units MIX1 to MIXN may be formed by digital circuits. Also, a computer program that exhibits the functions of the harmonic generation unit HMC and the synthesis units MIX1 to MIXN formed by a digital circuit is created, and the computer program is executed by a digital signal processor (DSP) or a microprocessor (MPU). It may be.

  In the harmonic generation unit HMC of the embodiment described above, the adjacent n-order harmonics Ssw (n) and n + 1-order harmonics that fall within the range of the reproducible frequency band of the main speaker from the low-frequency effect signal Ssw. The harmonic component SHM having the wave Ssw (n + 1) is generated and supplied to the synthesis units MIX1 to MIXN. As a modification, the second order, the third order, the fourth order, etc. from the low-frequency effect signal Ssw. May be generated and supplied to the synthesis units MIX1 to MIXN as the harmonic component SHM.

  In this modified example, the correction channel signals SMIX1 to SMIXN include harmonics outside the reproducible frequency band of the main speaker, but the main speaker reproduces only the harmonics within the reproducible frequency band in the first place. Since the harmonics outside the reproducible frequency band are ignored, the sound of the difference component between the adjacent harmonics Ssw (n) and Ssw (n + 1) within the reproducible frequency band is felt as a low tone. Therefore, it is possible to realize a sound field with a sense of presence.

  Further, the correction channel signals SMIX1 to SMIXN include adjacent harmonics and non-adjacent harmonics. However, in human auditory characteristics, strong sensitivity to difference components of reproduced sound due to adjacent harmonics. Since the sensitivity is low with respect to the reproduced sound due to the harmonics that are not adjacent to each other, the same low sound as the low sound reproduced by the low-frequency effect signal Ssw can be felt strongly. For this reason, even if the harmonics generated from the low-frequency effect signal Ssw are directly supplied to the main speaker via the synthesis units MIX1 to MIXN, the low volume of the low sound can be improved, and the connection of the sound image due to the low sound can be improved. The sound field can be improved, and a realistic sound field can be realized.

  Further, in order to extract adjacent harmonics from the harmonics generated from the low-frequency effect signal Ssw, for example, a bandpass filter or the like is required. Therefore, the number of parts in the sound reproduction system can be reduced, the configuration can be simplified, and the like.

  In the above description, the synthesis units MIX1 to MIXN included in the sound reproduction system 1 of the present embodiment synthesize the harmonic component SHM and the channel signals S1 to SN of the main channels and supply them to the main speakers. As another modification, each of the combining units MIX1 to MIXN includes level adjusting means (for example, a variable gain amplifier) for adjusting the signal level of the harmonic component SHM. A configuration may be adopted in which each harmonic component amplified by the amplifier (each harmonic component after amplification) and the channel signal of each main channel are combined to generate the correction channel signals SMIX1 to SMIXN of each channel.

  According to this further modification, the volume of the harmonic component reproduced by each main speaker of the main channel can be adjusted by adjusting the amplification factor of each amplifier described above, so that there is no sense of incongruity for the listener. Sound image localization can be realized.

  That is, the signal level of the harmonic component supplied to the main speaker provided in front of the listener by the level adjusting means is higher than the signal level of the harmonic component supplied to the main speaker provided behind the listener. If the level is adjusted to a large level, the bass sound that the listener feels based on the sound of the harmonic component (adjacent harmonic) (difference component sound) reproduced by the front main speaker described above The sound image of the low frequency sound that the listener feels based on the harmonic component (adjacent harmonic) sound (difference component sound) reproduced by the rear main speaker described above is localized forward for the listener. You can feel like you are. For this reason, it is possible to realize a multi-channel surround sound field that does not give the listener a feeling that bass sounds come from an unnatural place and can give a natural feeling without a sense of incongruity.

  Further, the listener may adjust the above-described level adjusting means (for example, variable gain amplifier) provided in the synthesis units MIX1 to MIXN. According to such a configuration, the listener himself / herself can adjust the volume of the harmonic component sound to be reproduced by each main speaker of the main channel, so that the adjustment suitable for the auditory characteristic of the listener can be performed.

  For example, the harmonic component supplied to the main speaker provided behind the listener by the signal level of the harmonic component supplied to the main speaker provided in front of the listener by the level adjustment means. If the signal level is adjusted to be higher than the above signal level, the bass sound felt by the listener based on the harmonic component (adjacent harmonic) sound (difference component sound) reproduced by the front main speaker described above The sound image by the low-frequency sound that the listener feels based on the harmonic component (adjacent harmonic) sound (difference component sound) reproduced by the rear main speaker described above is localized forward for the listener. Can feel like. Therefore, it is possible to realize a multi-channel surround sound field that can give a natural feeling without a sense of incongruity without giving the listener a feeling that bass sounds come from an unnatural place.

  Next, a more specific embodiment will be described with reference to FIGS. FIG. 3 is a block diagram showing the configuration of the sound reproduction system of the present embodiment, and the same or corresponding parts as those in FIG. FIG. 4 is an explanatory diagram showing the positional relationship of the speakers installed in the passenger compartment of the automobile.

  As shown in FIG. 4, the sound reproduction system 1 of the present embodiment shown in FIG. 3 is provided in an audio set AU that is installed in a vehicle cabin. Further, the audio set AU receives a disc player that reads and reproduces a 5.1 channel multi-channel source recorded on an information recording medium such as a DVD audio or a super audio CD, or a terrestrial digital broadcast. A signal source 2 such as a receiver that outputs a one-channel multi-channel source is provided.

  Then, the sound reproduction system 1 inputs 5.1-channel multichannel sources (each channel signal) SFL, Sc, SFR, SRL, SRR, Ssw output from the signal source 2 and receives a predetermined later-described signal. The signal processing is performed to generate correction channel signals SMIX1 to SMIXN, and the center speaker C installed at the center of the front panel of the front seat in the vehicle interior, the left front speaker FL and the right front installed on both sides of the front seat The speaker FR is supplied to the left rear speaker RL and the right rear speaker RR installed on both sides of the rear seat, and the low-frequency effect signal Ssw is supplied to the subwoofer speaker SW.

  In FIG. 3 again, the sound reproduction system 1 of the present embodiment is configured to include a harmonic generation circuit HMC and synthesis circuits MMIX1 to MMIX5 provided in each of the five channels.

  The harmonic generation circuit HMC is formed of an electronic circuit having a nonlinear input / output transfer function, like the harmonic generation unit HMC of the embodiment. Then, the low-frequency effect signal Ssw of the surround channel (0.1 channel) supplied from the signal source 2 is input, and a harmonic of the low-frequency effect signal Ssw is generated by a nonlinear input / output transfer function. Output as component SHM.

  The harmonic generation circuit HMC of the present embodiment does not extract and output adjacent harmonics as harmonic components SHM from the harmonics generated from the low-frequency effect signal Ssw. Harmonics such as second order, third order, and fourth order generated from the signal Ssw are directly output as the harmonic component SHM.

  As shown in the figure, the synthesis circuits MIX1 to MIX5 include amplifiers 3FL, 3c, 3FR, 3RL, and 3RR for amplifying the harmonic components SHM, and adders (synthesizers) 4FL, 4c, 4FR, 4RL, and 4RR, respectively. Is formed. In addition, the amplifiers 3FL, 3c, 3FR, 3RL, and 3RR are purchased as variable gain amplifiers and audio sets AU that can adjust their amplification factors when the audio set AU is adjusted when shipping the product. The above-mentioned listener or the like is formed of a variable gain type amplifier capable of adjusting the amplification factor.

  The synthesis circuit MIX1 adds (synthesizes) the channel signal SFL of the front seat left channel from the signal source 2 and the output of the amplifier 3FL to generate a correction channel signal SMIX1, and supplies it to the speaker FL of the front seat left channel. Supply.

  The synthesis circuit MIX2 adds (synthesizes) the center channel channel signal Sc from the signal source 2 and the output of the amplifier 3c to generate a correction channel signal SMIX2 and supplies it to the center speaker C.

  The synthesis circuit MIX3 adds (synthesizes) the front seat right channel channel signal SFR from the signal source 2 and the output of the amplifier 3FR to generate a correction channel signal SMIX3 and supplies it to the front seat right channel speaker FR. .

  The synthesis circuit MIX4 adds (synthesizes) the channel signal SRL of the rear seat left channel from the signal source 2 and the output of the amplifier 3RL to generate a correction channel signal SMIX4 and supplies it to the speaker RL of the rear seat left channel. .

  The synthesis circuit MIX5 adds (synthesizes) the channel signal SRR of the rear seat right channel from the signal source 2 and the output of the amplifier 3RR to generate a correction channel signal SMIX5 and supplies it to the speaker RR of the rear seat right channel. .

  The low-frequency effect signal Ssw from the signal source 2 is transferred to the subwoofer speaker SW and supplied.

  According to the sound reproduction system 1 having such a configuration, the following effects can be obtained.

  For example, since the center speaker C and the speakers FL, FR, RL, and RR are installed in a restricted place such as a passenger compartment, the lowest reproducible frequency (low-frequency cutoff) is lower than that of the subwoofer speaker SW. In the case of small speakers having a relatively high frequency), these speakers C, FL, FR, RL, and RR cannot reproduce bass sounds in the same low frequency band as the bass sounds reproduced by the subwoofer speaker SW. In the conventional sound reproduction system, the bass sound is exclusively emitted from the subwoofer speaker SW installed behind the occupant, giving the impression that the occupant who is the listener can hear sound from an unnatural place. Or the sound volume of the bass sound itself is insufficient, the connection of the sound image due to the bass sound is interrupted, and a sense of incongruity is felt. To lead to not be able to be current.

  However, in the sound reproduction system 1 of this embodiment, the correction channel signals SMIX1 to SMIX5 in which the harmonic component SHM is synthesized are supplied to the center speaker C and the speakers FL, FR, RL, RR. , FL, FR, RL, RR, HR, HR, HR, RR, RR, RR, RR, RR, HR Thus, it is possible to have the same feeling as listening to a low tone by the low-frequency effect signal Ssw.

  For this reason, the low volume reproduced by the subwoofer speaker SW based on the low-frequency effect signal Ssw and the low sound reproduced by the speakers C, FL, FR, RL, and RR and felt by the listener cause a low sound volume. It can be improved, it can be prevented from giving an impression that sound can be heard from an unnatural place, and the connection of sound images due to low sounds can be improved. A natural sound field can be realized.

  As described above, in the sound reproduction system 1 of the present embodiment, the small speaker having the lowest reproducible frequency (low frequency cut-off frequency) as compared with the subwoofer speaker SW is the center speaker C and the speakers FL, FR, RL. Even when installed as an RR, a natural sound field with a more realistic sensation can be realized, so that it exhibits an excellent effect as a sound reproduction system for car audio installed in the interior of an automobile. is there.

  Furthermore, according to the sound reproduction system 1 of the present embodiment, the same effect as that of the modification of the embodiment can be obtained. That is, from the harmonics generated from the low-frequency effect signal Ssw, adjacent harmonics are not extracted and synthesized as the harmonic components SHM into the signals SFL, Sc, SFR, SRL, SRR of each main channel. There is no need to provide a path filter or the like. For this reason, the number of parts in the sound reproduction system 1 can be reduced, the configuration can be simplified, and the like.

  Furthermore, the synthesis units MIX1 to MIXN are provided with amplifiers 3FL, 3c, 3FR, 3RL, 3RR as level adjusting means for adjusting the level of the harmonic component SHM, so that the listener himself can use these amplifiers 3FL, By adjusting the gains of 3c, 3FR, 3RL, and 3RR, the listener's auditory characteristic (that is, the auditory characteristic that feels the difference component of the frequency of the reproduced sound most strongly) can be extracted more effectively. For example, a listener such as a driver adjusts the amplification factors of the amplifiers 3FL, 3FR, 3RL, and 3RR as appropriate, and the harmonic components supplied to the main speakers FL and FR provided at the front left and right of the listener. When the signal level is adjusted to be higher than the signal level of the harmonic component supplied to the main speakers RL and RR provided at the left and right of the listener, the signal is reproduced by the front left and right main speakers FL and FR. The low sound felt by the listener based on the harmonic component (adjacent harmonic) sound (difference component sound) and the harmonic component (adjacent harmonic) reproduced by the main speakers RL and RR on the left and right It is possible for the listener to feel that the sound image due to the low sound felt by the listener based on (the difference component sound) is localized forward. Therefore, it is possible to realize a multi-channel surround sound field that can give a natural feeling without a sense of incongruity without giving the listener a feeling that bass sounds come from an unnatural place.

  In addition, the listener himself / herself adjusts the amplification factor of the amplifiers 3FL, 3c, 3FR, 3RL, and 3RR, so that the listener himself / herself adjusts the volume so that the difference component of the frequency of the reproduced sound due to the adjacent harmonics is felt most strongly. be able to. From this, it is possible to improve the sound volume shortage of the bass, improve the connection of the sound image due to the bass, and realize a sound field with a sense of realism.

  In the embodiment described above, when the multichannel sources SFL, Sc, SFR, SRL, SRR, and Ssw supplied from the sound source are analog signals, the harmonic generation circuit HMC and the synthesis circuits MIX1 to MIXN are analog. If the multichannel sources SFL, Sc, SFR, SRL, SRR, Ssw supplied from the sound source are digital signals, the harmonic generation circuit HMC and the synthesis circuits MIX1 to MIXN are digital circuits. May be formed. In addition, a computer program that exhibits the functions of the harmonic generation circuit HMC formed by a digital circuit and the synthesis circuits MIX1 to MIXN is created, and the computer program is executed by a digital signal processor (DSP) or a microprocessor (MPU). It may be.

  Further, in the present embodiment described above, as illustrated in FIG. 4, the subwoofer speaker SW is described as being provided behind the rear seat (the trunk room side) of the vehicle interior. Even when provided at other positions (for example, on the left and right sides of the rear seat), it is possible to realize a sound field that provides a sense of realism. That is, in this embodiment, the listener such as the driver can adjust the amplification factors of the amplifiers 3FL, 3c, 3FR, 3RL, and 3RR as appropriate. The signal level of the harmonic component supplied to the main speakers FL and FR provided in the speaker is higher than the signal level of the harmonic component supplied to the main speakers RL and RR provided on the left and right sides of the listener. When adjusted in this way, the bass sound felt by the listener based on the sound (difference sound) of the harmonic components (adjacent harmonics) reproduced by the front left and right main speakers FL and FR, and the rear left and right main speakers RL , The sound image due to the low-frequency sound felt by the listener based on the sound of the harmonic component (adjacent harmonics) reproduced by RR (difference component sound) is felt to be localized to the listener. Can. For this reason, even if the mounting position of the subwoofer speaker SW that receives the low-frequency effect signal Ssw and emits the low sound is changed, the listener does not feel that the low sound comes from an unnatural place. It is possible to realize a multi-channel surround sound field that can give a natural feeling without any sense of incongruity.

FIGS. 1A, 1B and 1C are explanatory views for explaining a conventional sound reproduction system. FIG. 2A is a block diagram showing the configuration of the sound reproduction system of the embodiment, and FIG. 2B is an explanatory diagram for explaining the function. It is a block diagram showing the structure of the sound reproduction system of an Example. It is explanatory drawing for demonstrating the installation position of the speaker in case the sound reproduction system shown in FIG. 3 is installed in the vehicle interior of a motor vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sound reproduction system 2 ... Signal source HMC ... Harmonic generation part (harmonic generation circuit)
MIX1 ~ MIX5, MIXN ... Synthesizer (synthesizer circuit)
3FL, 3c, 3FR, 3RL, 3RR ... Amplifier 4FL, 4c, 4FR, 4RL, 4RR ... Adder

Claims (6)

A sound reproduction system for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source,
Harmonic generation means for generating harmonics of the low-frequency effect signal of the surround channel supplied to the subwoofer speaker;
Combining means for synthesizing the harmonic component and the channel signal of the main channel to generate a correction channel signal and supplying it to the main speaker;
A sound reproduction system comprising: A sound reproduction system for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source,
Generate harmonics of the low-frequency effect signal of the surround channel supplied to the subwoofer speaker, and adjacent harmonics within the reproducible frequency band of the main speaker from the generated harmonics Harmonic generation means for extracting
Combining means for synthesizing adjacent harmonic components extracted by the harmonic generating means and the channel signal of the main channel to generate a correction channel signal and supplying the correction channel signal to the main speaker;
A sound reproduction system comprising: Further, the synthesizing means includes level adjusting means for amplifying the harmonic component for each channel,
Combining the amplified harmonic component and the channel signal of the main channel to generate the correction channel signal;
The sound reproduction system according to claim 1 or 2, characterized by the above-mentioned. A sound reproduction method for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source,
A harmonic generation step of generating harmonics of the low-frequency effect signal of the surround channel supplied to the subwoofer speaker;
Combining the harmonic component and the channel signal of the main channel to generate a correction channel signal and supplying it to the main speaker;
A sound reproduction method comprising: A sound reproduction method for causing a subwoofer speaker and a main speaker to perform multichannel surround reproduction based on a multichannel source,
Generate harmonics of the low-frequency effect signal of the surround channel supplied to the subwoofer speaker, and adjacent harmonics within the reproducible frequency band of the main speaker from the generated harmonics A harmonic generation process for extracting
Combining the adjacent harmonic components extracted in the harmonic generation step and the channel signal of the main channel to generate a correction channel signal and supplying the correction channel signal to the main speaker;
A sound reproduction method comprising: Furthermore, the synthesis step includes a level adjustment step of amplifying the harmonic component for each channel,
Combining the amplified harmonic component for each channel and the channel signal of the main channel to generate the correction channel signal;
The sound reproduction method according to claim 4 or 5, wherein

Images