MXPA97003511A - Ru cancellation apparatus - Google Patents

Abstract

An apparatus for reducing acoustic background noise for common use with a telephone transmitter receiver assembly (10) or a microphone device (100) on a microphone carrier support or a telephone receiver-transmitter assembly (401) on a microphone carrier support or the like. The apparatus includes a first (12) and a second (14) microphones that are arranged such that the first microphone (12) receives a desired speech input and the background noise present in the vicinity of the speech, and the second microphone (14). ) receives substantially only the background noise. The background noise of the second microphone (14) is converted into a corresponding electrical signal and subtracted (16) from a signal corresponding to the speech and background noise obtained

Description

NOISE CANCELLATION APPARATUS RELATED REQUESTS This application is a continuation in part of the permitted application Serial No. 07 / 968,180, filed on October 29, 1992, incorporated in the present by reference. Reference is also made to U.S. Patent No. 5,251,263, issued October 5, 1993, and incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a noise canceling apparatus, and more particularly, to an apparatus for canceling or reducing background acoustic noise for use with a telephone receiver-transmitter assembly (telephone apparatus consisting of a microphone and an earphone) mounted on a support whose shape allows it to be held by hand) or a microphone device on a holder with a microphone holder or a set REF. 24704 telephone receiver-transmitter in support of a microphone holder or the like.

Description of the prior art As will be appreciated, in many situations, the presence of background noise is undesirable. As an example, consider the situation in which an operator is attempting to conduct a telephone conversation from a telephone or similar device located in a noisy area. In this situation, the acoustic, high, background noise is received by a microphone in the telephone receiver-transmitter assembly of the telephone and converted to an electrical signal that is supplied to the telephone (s) of the telephone (s). person (s) who has the conversation with the operator and becomes the same to an acoustic signal. As a result, the person to whom the operator is constantly communicating, hears the loud background noise. Additionally, when the person is speaking, the speech is combined with the background noise and as such, it may be difficult for the other person (s) to understand. As a result, the operator may have to yell into the telephone microphone. Additionally, the signal representing the background noise is also supplied from the microphone in the operator's telephone receiver-transmitter assembly to the receiver or loudspeaker in the operator's telephone receiver-transmitter assembly. In this way, the operator also constantly hears background noise from the headset or loudspeaker in the operator's telephone receiver-transmitter assembly, and when the other person is talking, it may worsen the understanding of the same. As another example, consider the situation in which a pilot who is operating a helicopter or similar, wishes to communicate with another person by means of radio frequency (RF) communication. In this situation, typically, the pilot speaks in a so-called microphone in a microphone-holder support or a telephone receiver-transmitter assembly in a microphone-holder support which is coupled to a radio transmission / reception device after which the speech is converted into RF signals that are transmitted to a second receiver-transmission device and become the same in speech to be heard by the other person (s). As with the previous situation of a telephone located in a noisy area, the high background noise of the helicopter is received and converted into an electrical signal by the microphone device in a microphone-holder support or telephone receiver-transmitter assembly and is subsequently supplied to the device of reception. As a result, the person (s) who communicates with the pilot hears the loud background noise. This can be particularly annoying when the pilot leaves the radio / receiving device in the "ON" position while the helicopter is operating. As yet another example, consider the systems of verification and / or speech recognition in which an operator must speak to have access, for example, to a physical environment or, to operate a computer or an automatic computer machine. It must be prevented that background noise has access (no recognition or verification due to background noise) or false access can be provided by a false verification. In an attempt to reduce background noise to improve the performance of a telephone or microphone in a microphone holder support or telephone receiver-transmitter assembly or the like located in a noisy or similar environment, pressure gradient microphones can be used. Basically, a pressure gradient microphone responds to the difference in pressure at two closely spaced points. When used in an environment where the pressure gradient of the background noise is isotropic, the electrical signal produced by the pressure gradient microphone due to this background noise is effectively zero. However, in most real situations, the pressure gradient of the background noise is not isotropic, and as a result, in these situations, the performance of the pressure gradient microphone is adversely affected. Additionally, since the voice or speech propagates in more than one direction, the electrical signal produced by the microphone corresponding to it is often degraded. In this way, even if a pressure gradient microphone is used in either a telephone receiver-transmitter assembly or a microphone in a microphone holder, the desired amount of background noise cancellation may not be sufficient and may not be adequate. performance. In addition, since the two opposite sides of a pressure gradient microphone respond to acoustic pressure, as mentioned previously, the telephone receiver-transmitter assembly of an existing telephone will have to be substantially modified to allow these two sides of the microphone to respond to the acoustic pressure. Additionally, as a result of using this microphone in a telephone receiver-transmitter assembly, electrical signals produced from it must be amplified. Thus, replacing the conventional microphone in a telephone receiver-transmitter assembly of an existing telephone with a pressure gradient microphone would typically require the replacement of the telephone receiver-transmitter assembly with a new telephone receiver-transmitter assembly and as such, would be relatively expensive As an alternative to using gradient pressure microphones, an acoustic feedback type system should be used. This system usually includes compensation filters that are used to equalize the transfer function of the headphones or loudspeakers. Since the characteristics of the loudspeakers or headphones are tightly controlled by these filters, the cost of the filters is relatively high. As a result, typically these acoustic feedback systems are relatively expensive. In this way, the prior art has failed to provide a relatively low cost means for reducing background noise to an acceptable level for use with telephones and / or microphone devices in a microphone holder support or the like, and an effective means of the cost to allow existing phones to reduce background noise to an acceptable level.

OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide a noise reduction apparatus that overcomes the problems associated with the prior art. More specifically, it is an object of the present invention to provide a noise reduction apparatus that reduces background noise to an acceptable level. Another object of the present invention is to provide a noise reduction apparatus as mentioned above for use in a telephone or microphone in a microphone holder support or telephone receiver-transmitter assembly device or to provide a noise reduction microphone device or similar. It is yet another object of the present invention to provide a noise reduction apparatus as mentioned above that is relatively inexpensive.

It is still another object of the present invention to provide a noise reduction apparatus relatively low in cost, for use with telephones that can be operated with online, available, normal energy. A still further object of the present invention is to provide a relatively low noise reduction apparatus at cost that is easily adaptable to the telephone receiver-transmitter assemblies of existing telephones that is operable with the available, normal, online power. In accordance with one aspect of this invention, a telephone receiver-transmitter assembly apparatus is provided for use with a telephone operable by the normal power supplied by the telephone receiver-transmitter assembly for transmitting and receiving signals representing speech between two or more operators The apparatus includes a housing having a first microphone means for receiving a first acoustic signal composed of the speech of the operator using the apparatus and the background noise in the vicinity of the speech and for converting the first acoustic sound to a first signal, and a second microphone means arranged at a predetermined angle with respect to the first microphone means for receiving a second acoustic sound substantially composed of the background noise and for converting the second acoustic sound to a second signal; and a device for subtracting the second signal from the first signal to obtain a signal that substantially represents speech. In another aspect of the invention there is provided a microphone in a microphone-holder support or a telephone receiver-transmitter device for transmitting and receiving signals representing speech by at least one, preferably two or more operators. The device includes a housing having a first microphone means for receiving a first acoustic signal composed of the operator's speech using the device and the background noise in the vicinity of the speech and for converting the first acoustic sound to a first signal and a second microphone means arranged at a predetermined angle and / or distance with respect to the first microphone means for receiving a second acoustic signal composed substantially of the background noise and for converting the second acoustic sound to a second signal; and an apparatus for subtracting the second signal from the first signal to obtain a signal that substantially represents speech. The microphone in microphone holder support or telephone receiver-transmitter assembly can be used in flight (for example, helicopter or airplane) or in other equipment such as telephones, or for example, recognition and / or voice verification systems, to have access to a physical medium or a computer (either via direct or indirect interface or via telephone lines) or to an automatic computer machine or, in other systems of recognition and / or verification. The first and second microphones arranged at a predetermined angle and / or distance with the subtraction apparatus described herein may also be used in the area of ambient noise cancellation for microphones in acoustic or telemetry monitoring or even directional microphones such as as directional microphones with side lobes of irradiation. Other objects, features and advantages in accordance with the present invention will become apparent from the following detailed description of the illustrated embodiments when read in conjunction with the accompanying drawings in which corresponding components are identified by the same reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a telephone having a noise reduction apparatus according to an embodiment of the present invention; Figure 2 is a block diagram of the noise reduction apparatus used in the telephone of Figure 1; Figure 3A is a front plan view of the receiving portion of Figure 1; Figure 3B is a side elevational view of the receiver portion of the telephone of Figure 1 with the top removed; Figure 4 is a schematic diagram of the block diagram of Figure 2; Figure 5 is another schematic diagram of the noise reduction apparatus illustrated in Figure 2; and Figures 6A, 6B and 6C illustrate a microphone devices in a microphone holder support using a noise reduction apparatus according to an embodiment of the present invention; Figures 7A and 7B are schematic diagrams to which reference will be made in the explanation of the operation of the present invention; Figure 8 illustrates a noise reduction apparatus according to the present invention; Figures 9A, 9B, 9C, 9D and 9E illustrate the microphone modes in the microphone carrier support and telephone receiver-transmitter assembly of the invention (Figures 9A and 9B showing each embodiment having a particular microphone placement; shows an overview of the telephone receiver-transmitter assembly and Figures 9D and 9E showing side views of the microphone in a microphone holder support); Figures 10A and 10B are schematic diagrams of the noise reduction apparatus of Figure 8; Figure 11 illustrates a phase inversion circuit; Figure 12 illustrates an opposingly charged microphone circuit; Y Figures 13A and 13B illustrate the active cancellation curves of the embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Figure 1 illustrates a telephone 8 using a noise reduction apparatus according to an embodiment of the present invention. As shown therein, the telephone 8 generally includes a telephone receiver-transmitter assembly 10, having a portion 41 of a receiver or loudspeaker and a receiver portion 42, and a telephone unit 18 that can be coupled between them by means of a telephone cord 48. Alternatively, the telephone can be a wireless type telephone and as such, the telephone receiver-transmitter assembly 10 is coupled to the telephone unit 18 by means of RF waves. The receiving portion 42 includes a first and a second microphones 12 and 14, respectively (Figure 2), a switch 40 for adjusting the volume of a signal supplied to the loudspeaker portion 41 or earphone, and a lid 48 having a portion 44 cupped and a 46 mesh portion. Figure 2 illustrates the telephone 8 in the form of a block diagram. As shown therein, the telephone receiver-transmitter assembly 10 generally includes first and second microphones 12 and 14, respectively, a subtraction device 16, which in a preferred embodiment is an operational amplifier ("op-amp"). , of its abbreviation in English), an amplifier 20 which is preferably an op-amp, and a loudspeaker or earphone 22. The first and second microphones 12 and 14, respectively, the op-amp 16 and the amplifier 20 are preferably contained within the receiving portion 42 (see Figure 1). The composite acoustic signals of the speech or the like and the background noise are supplied to the first microphone 12 and become the same in a corresponding electrical signal which is subsequently supplied to the plus sign terminal (+) of the op-amp 16. background noise is supplied to the second microphone 14 and becomes the same in a corresponding electrical signal which is then supplied to the minus sign (-) terminal of the op-amp 16. The op-amp 16 is adapted to subtract the signal of noise of the second speech microphone 14 and the noise signal of the first microphone 12 and for supplying therewith an electrical signal substantially representing speech to the telephone unit 18, after which the speech signal is transmitted from the same through the telephone lines to a desired telephone or telephones. The output signal of the op-amp 16 is also combined in the telephone unit 18 with a signal received from the telephone lines and is supplied to the amplifier 20. The op-amps 16 and 17 are preferably integrated circuits with relatively low power (IC, for its acronym in English), such as complementary metal oxide semiconductors (CMOS, for its acronym in English), and can be built either from one or more CMOS IC chips. Although not shown in Figure 2, the amplifier 20 can be set selectively for the use of the switch 40 (Figure 1) by the operator to adjust the amplification of the received signal to a desired level. The amplified signal of the amplifier 20 is supplied to the loudspeaker 22, after which the amplified signal becomes an acoustic signal to be heard by the operator. Figures 3A and 3B illustrate two views of the receiving portion 42, in which the lid 48 is removed in the view of Figure 3A. As shown therein, the receiving portion 42 generally includes a housing 74, a circuit board assembly 78, the first and second microphones 12 and 14, respectively, and the cover 48. The first and the second microphones 12 and 14, respectively, which are preferably electret microphones or similar microphones, are arranged or placed as described below. These microphones are held in place or secured by a retention member 76, which can be constructed of a foam-like material, which in turn is secured to the housing 74. The respective outputs of the first and second microphones 12 and 14 are supplied through respective wires (not shown) to the op-amp 16 that is contained in the circuit board assembly 78 which in turn attaches to the housing 74. As described more fully herein below, the board 78 of circuit may contain additional circuit elements to process the signals received from the first and second microphones and to amplify the signals for delivery to the loudspeaker or earphone 22 (Figure 2). A cover 72 that is attached to the housing 74 can be used by the use of adhesives or the like or alternatively it can be sonically soldered together. The cover 72 and the housing 74 with the circuit board assembly 78, the retaining member 76 and the first and second microphones 12 and 14 form an assembly 71. The layer 48, which can be constructed of a plastic-like material such as polycarbonate, includes an annular side member 43 and a portion 45 having a typical thickness T which engages the side member 43 and is arranged to be lower than the upper portion of the side member by a predetermined minimum amount such as 0.051 cm (0.020) one inch), thereby creating a recessed portion 44. The portion 45 includes a portion 46 having a thickness T 'that is less than the thickness T and having a plurality of through holes contained therein and may resemble a mesh-like portion. In a preferred embodiment, the thickness T 'of the portion 46 has a thickness of less than 0.076 cm (0.030 of an inch). Since the portion 46 represents a relatively small amount of the portion 45, the reduction in thickness therein does not adversely affect the complete structural rigidity of the layer 48. Alternatively, the portion 46 can be constructed of a further material. strong, for example stainless steel or similar material, and is combined with the portion 45. As will be appreciated, by arranging the portions 45 and 46 to separate from the upper portion of the side member 43, even when the portion 42 recipient is placed on a surface, the member 43 side, and none of the portions 45 or 46, make contact with this surface. As a result, no charge is directly hit on the portion 45 and / or the portion 46, but is actually transmitted to the side member 43. The layer 48 is placed on the assembly 71 so that the first and second microphones 12 and 14, respectively, are arranged below the portion 46 with the first microphone positioned relatively close to the underside of the portion 46. In this way , the speech travels a relatively short distance from an operator, who is speaking at the receiving portion 42 from a distance preferably less than 1 inch, through the portion 46 to the first microphone. As a result, acoustic distortions are minimized.

The arrangement of the first and second microphones 12 and 14, respectively, within the receiving portion 42 is illustrated in Figures 3A and 3B. More specifically, as shown in Figure 3B, the first and second microphones are arranged to have an angle 0 between them, which preferably has a value in a range between 30 ° and 60 °. The first and second microphones are additionally arranged accordingly to have an angle? and [(90-?) + 0] between a plane parallel to the receiving or "responsive" surface of the first microphone 12 and the speech direction of an operator, and an axis normal to the sensitive surface of the second microphone 14 and the address of speech, as shown in Figure 3B; to have an angle? between the speech direction and the second microphone, as shown in Figure 3A In a preferred embodiment, the angle? has a value of less than approximately 35 ° and the angle? it has a value of approximately 180 °. As a result of arranging the first and second microphones in this manner, the first microphone 12 receives both the operator's speech and the background acoustic noise that is present in the vicinity, and the second microphone 14 receives essentially only the same acoustic background that is received by the first microphone.

Although, as mentioned previously, the angle 0 has a value that is preferably between 30 ° and 60 °, the first and second microphones 12 and 14, respectively, can nevertheless operate satisfactorily even if they are arranged to have an angle 0 that is outside of this range. However, as the angle 0 becomes substantially smaller than 30 ° or greater than 60 °, performance may be adversely affected. That is, when the angle 0 becomes substantially smaller than 30 °, the second microphone 14 receives both speech and background noise, as a result, in the subtraction of the output signal of the second microphone 14 of the signal output of the first microphone 12, a portion or all of the speech can be canceled. On the other hand, when the angle 0 is substantially greater than 60 °, the background noise received by the second microphone 14 may not be similar to that received by the first microphone 12. As a result, the subtraction of the output signal the second microphone 14 of the output signal the first microphone 12 can not adequately cancel out the background noise received by the first microphone. In a similar way, although the angles? Y ? • have preferred values of less than 35 ° and approximately 180 °, respectively, as mentioned previously, the first and second microphones can operate satisfactorily even if they are arranged to have different values of these angles. However, according to the values of the angles? Y ? become substantially different from the respective preferred values, performance may be adversely affected. That is, when the angle? becomes substantially greater than 35 °, the second microphone 14 can receive both speech and background noise. Similarly, when the angle? is substantially smaller or larger than 180 °, the second microphone 14 can receive both speech and background noise. As a result, in any of these situations, in the subtraction of the output signal the second microphone 14 of the output signal of the first microphone 12, a portion or even all of the speech may be canceled. As will be appreciated, by using the devices and materials described above for the components of the receiving portion 42, the cost to build this receiving portion is relatively low. Furthermore, when using the COMS pellets, as previously described, the receiving portion remains relatively low in energy consumption. As a result, the receiving portion can be powered by the normal energy available in the telephone receiver-transmitter assembly, and as such, does not require additional power or transformers or the like. Additionally, although the receiver portion 42 has been described for assembly with the telephone receiver-transmitter assembly 10 of the telephone 8, which is a new telephone, this receiving portion, or a slight variation thereof, can be used in the receiver sets - telephone transmitters of existing telephones. That is, in this latter situation, the cap and microphone contained within the telephone receiver-transmitter assembly of an existing telephone are replaced only with the receiver portion 42. In this way, this use of the receiving portion 42 provides a relatively easy and inexpensive means for modifying a telephone receiver-transmitter assembly of an existing telephone to include the present noise reduction apparatus. Figure 4 illustrates a schematic diagram of a telephone circuit arrangement 8 shown in Figures 1 and 2. As shown in Figure 4, the first microphone 12 is coupled through a resistor 202, which is adapted to operate as a current limiting resistor for correcting the deviation of an output of the first microphone, to the input terminal 200, the first microphone 12 is further coupled through a resistor 210 to the plus sign terminal (+) of the op-amp 16 and through a resistor 212 to a variable resistor 214. The second microphone 14 is coupled through a variable resistor 208, which is adapted to operate as a current limiting resistor to correct the deviation and an output of the second microphone, to an input terminal 201, and a minus sign input. op-amp 16. The limiting resistor 208 is preferably a variable current limiting resistor which allows the level of the output signal of the second microphone to be fitted within a predetermined value at the level of the output signal of the first microphone 12. More specifically, the limiting resistor 208 allows the output signal of the second microphone 14 to be assigned a value such that when a signal having a similar level is transferred from the first microphone 12, the amplitude of the signal is minimized. the difference between these. The value of the current limiting resistors 208 can be selected according to the minimization criterion. An input terminal 198 is connected to the resistors 204 and 206, which are adapted to divide the received voltage into the input terminal 198, and to a minus-sign terminal (-) of the op-amp 16. The output of the op-amp 16 is coupled to the capacitors 220, 222 and 226 and the resistors 224 and 228 which in turn are connected to a "microphone input" terminal of the telephone unit 18. The output of the op-amp 16 is further coupled through a variable resistor 214, a resistor 216 and a capacitor 218 to ground. The resistors 210, 212 and 216 and the variable resistor 214 provide variable gain, for example, 20 to 1 of amplification, at the output of the op-amp 16. The capacitors 218, 220 and 222 are adapted to remove the levels of (direct current, of its abbreviation in English) that may be present in the output signal of the op-amp 16. The resistor 224 and 228 and the capacitor 226 are adapted to operate as a low pass filter having a point of break or a predetermined value, which, for example, can be 3.7 kHz. The telephone unit 18 is additionally connected to the telephone lines and adapted to receive the signals through the microphone input terminal and to supply these signals to the desired telephone or telephones by means of the telephone lines. The telephone unit 18 is further adapted to receive signals from another telephone or telephones by means of the telephone lines and to combine these signals with those received through the microphone input terminal, as previously described, and to supply the combined signal to a speaker terminal 231 of the loudspeaker input. The input terminal 231 is connected through a capacitor 230, which is adapted to block the signals from, and a resistor 232 to the minus sign terminal of an op-amp 17 and through a resistor 234 to a resistor 240. variable. An input terminal 199 is connected to the plus sign terminal of the op-amp 17. The output of the op-amp 17 is connected through the capacitors 242 and 244 and a resistor 246 to the speaker or handset 22. The output of the op -amp is additionally connected through the variable resistor 240, a resistor 238 and a capacitor 236 to ground. The operation of the telephone 8 shown in Figure 4 will now be described below. In the activation of the telephone receiver-transmitter assembly 10, when the telephone receiver-transmitter assembly 10 is lifted from the switch hook (not shown) or the like, the normal telephone line voltage to terminals 198, 199, 200 and 201 input. A signal from the first microphone 12, which has been corrected in the deviation by the current limiting resistor 202, is supplied through the resistor 210 to the plus sign terminal of the op-amp 16. An output signal from the second microphone 14 , which has been corrected in the deviation by the current limiting resistor 208, the minus sign terminal of the op-amp 16 is supplied. The op-amp 16 subtracts the signal received from the second microphone 14 from that received from the first microphone 12 and transfers the resulting subtracted signal. The levels that can be present in the output signal are removed and the signal is amplified. The high frequency signals, such as those above 3.7 kHz, are then removed from the amplified output signal and the resulting signal is supplied to the telephone unit 18. In this way, a voltage signal is supplied to the telephone unit 18 which is proportional to the difference between the voltages generated by the first and second microphones 12 and 14, respectively. An output signal from the telephone unit 18, which is a combination of the signals received through the microphone input terminal and the telephone lines, is supplied to the input terminal 231 of the amplifier 20. The signal of the terminal 231 input is supplied to capacitor 230 to remove any of the signals that may be present. The output of the capacitor 230 is supplied through the resistor 232 to the minus sign terminal of the op-amp 17. The op-amp 17 subtracts the signal from the telephone unit 18 of the signal received from the input terminal 199 and supplies a signal subtracted from it. This signal can be selectively amplified, by using the resistors 232, 234 and 238 and the variable resistor 240, by the operator by the use of the switch 40 (see Figure 1). Any of the signals that may be present in the amplified signal are subsequently removed by the capacitors 242, 244 and 236 • The output signal of the capacitor 244 is limited in current by the capacitor 246 and is subsequently supplied to the atrial speaker 22 for be converted into the same in an acoustic signal. Figure 5 illustrates an alternative arrangement for processing the signals obtained from the first and second microphones 12 and 14, respectively, to provide a current output to supply the telephone unit 18 that is provided to the difference of the voltages generated by the first and the second microphones. In more specific form, the circuit arrangement of Figure 5 includes a telephone receiver-transmitter assembly 10 'having a plurality of input terminals 300, 301, 370 and 390 that are each adapted to receive the available, normal line power. The first microphone 12 is coupled through a current limiting resistor 302 to the input terminal 300 and is further coupled to the plus sign terminal (+) of a subtraction device 316, which is preferably a CMOS op-amp. The output of the second microphone 14 is coupled through a current limiting resistor 308, variable to the input terminal 301 and further coupled to the minus sign terminal (-) of the op-amp 316. The signal transmitted from the op -amp 316 is supplied through the filtration stages 350 to the minus sign terminal of the subtraction device 351 which is preferably a CMOS op-amp. The filtering steps 350 are adapted to provide a predetermined, characteristic frequency response such as a progressive signal attenuation at a predetermined frequency. As will be appreciated, although two filtration steps are shown in Figure 5, any number of filtration layers can be used. The input terminal 390 is coupled to the resistors 392 and 394, which are adapted to reduce the signal supplied thereto, and to the plus sign terminal of the op-amp 351. An output signal is supplied from the op-amp 351 to the base of a transistor 366. The input terminal 391 is connected to a Zener diode 360, a capacitor 362 and a resistor 364 which in turn is connected to the collector of the transistor 366 and to the microphone input terminal of the unit. 18 telephone. The emitter of transistor 366 is coupled through resistor 367 and 368 to the minus sign terminal of op-amp 351 to provide a feedback circuit thereto. The op-amp 351 and the associated components provide electrical isolation between the filtering steps 350 and the transistor 366. The transient 366 is adapted to amplify the signal supplied to the telephone unit 18. The output of the telephone unit 18 is coupled to the input terminal 231 (Figure 4) and further processed in the manner previously described with reference to the telephone receiver-transmitter assembly 10 of Figure 4 to provide an acoustic signal from the loudspeaker or headset 22 The operation of the telephone 8 'will now be described below. By applying power to the telephone receiver-transmitter assembly 10 ', when lifting the telephone receiver-transmitter assembly from the switch hook (not shown) or the like, a normal telephone line voltage is applied to the terminals 300, 301, 370, 390 and 391 entry. A signal from the first microphone 12, which has been corrected in deviation by the current limiting resistor 302, is supplied to the plus sign terminal of the op-amp 316. An output signal from the second microphone 14, which has been corrected in deflection by the current limiting resistor 308, is supplied to the minus sign terminal of the op-amp 316. The resistor 308 is preferably a variable current limiting resistor which allows the level of the output signal of the second microphone 14 to be adapt within a predetermined value to the level of the output signal of the first microphone 12, in a substantially similar manner as that previously described for the resistor 208. The output difference signal of the op-amp 316 is provided through the steps 350 filtering, which may include one or more RC networks or equivalent circuits, to limit the upper frequency of the output signal to a predetermined value which, for example, it can be 3.7 kHz. The output signal of the filtering steps 350 is supplied to the minus sign terminal of the op-amp 351 and a voltage signal is supplied from the input terminal 390, which has been divided to a predetermined value such as half of the same, to the plus sign terminal of the op-amp 351 which in turn calculates the difference between these, and supplies an output signal corresponding to the base of the transistor 366. The voltage of the input terminal 391 is supplied through the resistor 364 to the collector of the transistor 366. As a result, an amplified signal from the telephone receiver-transmitter assembly 10 'is supplied to the telephone unit 18 for delivery therefrom through the telephone lines to the telephone (s) desired (s) and to be combined with a signal received from the telephone (s) for delivery to the input terminal 231 in a manner similar to that previously described with reference to Figure 4. The individual components Circuit duals without reference designations represented in FIGS. 4 and 5 are connected as shown and will not be discussed further, since the connections and values are apparent to those skilled in the art and are not necessary for an understanding of the present invention. . Figures 6A, 6B and 6C illustrate a microphone 100 in a microphone holder support using a noise canceling apparatus according to an embodiment of the present invention. More specifically, the microphone 100 in the microphone holder support generally includes a housing 174, a circuit board assembly 178, a first and second microphone 112 and 114, respectively, and a position 147. The housing 174, which can be The construction of either a metal-like plastic-like material includes a circular portion 108 having a hole therethrough to allow a shaft 106 to be inserted therein. As a result, the microphone 100 on the microphone holder support can rotate around the tree 106 as illustrated in Figure 6A. The first and second microphones 112 and 114 are respectively coupled to the circuit board assembly 178 by the wires 102 and 104. The circuit board assembly 178 contains the circuit system similar to that in the circuit board assembly 78, which, as previously described, processes the signals of the first and second microphones 12 and 14, respectively, for delivery to the telephone unit 18, and as such, in the interest of brevity, will not be further described herein. Therefore, the circuit board assembly 178 is adapted to receive a speech and background noise signal from the first microphone 112 and to subtract therefrom the background noise signal of the second microphone 114 to derive a signal that substantially represents speech. This signal is supplied to a transmission device (not shown) to be converted to an RF signal and transmitted to a remote receiving device (not shown). The first and second microphones 112 and 114, respectively, are held in place by a retaining member 176, which, for example, can be constructed of a foam-like material. A mesh-like screen 146, for example, which can be made from a plastic or metallic material or the like, is attached to the cut-off portion 147 to protect the first and second microphones, the mesh 146 has a predetermined thickness that , for example, it can be approximately 0.076 cm or less (0.030 or less than one inch). The first and second microphones 112 and 114, respectively, which can be electret microphones are arranged in a similar manner as that of the first and second microphones 12 and 14, respectively of the telephone receiver-transmitter assembly 10, previously described. That is, the first and second microphones 112 and 114 are respectively positioned to have an angle T 'and [(90 -?') +?] Between a plane parallel to the receiving or sensitive surface of the first microphone and the direction of the speaks of an operator, and between a normal axis to the sensitive surface of the second microphone and the direction of speech, as shown in Figure 5A. In addition, the first and second microphones 112 and 114 respectively, are arranged to have an angle 0 'between them, which has a preferred value in a range between 30 ° and 60 °. The first and second microphones 112 and 114, respectively, are located in a vicinity relatively close to the mesh 146 and the cutting portion 147 of the housing 174 so as not to receive acoustic sounds that have become unacceptably distorted. Although the above embodiments have been described as having only a first microphone 12 (112) and a second microphone 14 (114), the invention is not so limited and any number of microphones can be used for the first microphone and / or the second microphone. For example, a receiver portion 42 '(not shown) can be configured to include two or more microphones that operate as a first microphone 12' (not shown) and two or more microphones that operate as a second microphone 14 '(not shown) . In this configuration, when multiple microphones are used for the first and / or second microphones, respective variable current limiting resistors are preferably provided for each of the microphones for the first microphone 12 'and for each of the microphones for the second microphone 14 '. In this way, the outputs of the first and second microphones 12 'and 14', respectively, will comprise a weighted sum of the various output voltages of the microphones. The current limiting resistors are preferably set at respective values to minimize something functional from the difference of the first and second microphone 12 'and 14', respectively. The criteria for selecting the values of the current limiting resistor or equivalently the weighting function of each microphone could be selected according to any well-known gradient search algorithm, to minimize the functional ones.

Figure 9A illustrates a microphone carrier support 320 having a first microphone 300 and a second microphone 302 arranged therein. The first microphone 300 includes a pressure sensitive surface 301 and the second microphone 302 includes a second pressure sensitive surface 303. As shown in Figure 9A, the first and second microphones 300 and 302 are arranged such that the respective pressure sensitive surfaces 301 and 303 are substantially separated from each other by 180 ° "the microphones 300 and 302 are further arranged. to have a structural acoustic screen 322 between the microphones. This structural acoustic screen 322 may be comprised of a structural member adapted to provide acoustic separation between the microphones. Alternatively, an acoustic screen arrangement could be used in place of the structural member. Furthermore, as shown in Figure 9A, the first and second microphones 300 and 302, and in particular their respective pressure-sensitive surfaces 301 and 303, are located within a distance or dimension b. The first microphone 300 is adapted to receive the acoustic sound such as the speech of a user and to convert this received acoustic speech into a signal corresponding to this speech. This first microphone 300 can also receive the background noise that may exist. As will be appreciated, this background noise is combined with the speech of the operator, and as such, the signal provided by the first microphone corresponds to both the user's speech and the background noise. On the other hand, the second microphone 302 is arranged inside the microphone carrier support 320 to receive mainly only the background noise. In more specific form, the pressure-sensitive surface 303 of the second microphone 302 is preferably arranged at an angle of 180 ° from the pressure-sensitive surface 301 of the first microphone 300. Furthermore, as mentioned previously, the first and the second microphones 300 and 302 have a 322 acoustic plate arranged between them. This acoustic plate is adapted to minimize or prevent any speech from the user being received by the second microphone 302. Furthermore, the first and second microphones 300 and 302 are preferably arranged within the relatively close proximity to each other, ie, within the distance b. As an example, this container b can be located within a range of 0.254 to 1.27 cm (0.10 to 0.50 of an inch) preferably about 0.63 of an inch or less. The distance b can be completed by the person skilled in the art from its description, without the undue experiment, and the invention is not necessarily limited to a particular value for b. Figure 9B illustrates a microphone carrier support 330 having first and second microphones 300 and 302 arranged somewhat differently than in the microphone carrier support 320 of Figure 9A. That is, as shown in Figure 9B, the first and second microphones 300 and 302 are placed in a staggered side-to-side relationship with each other. In addition, an acoustic plate 332 is provided between the first and second microphones 300 and 302 to provide acoustic speech separation in a manner similar to that provided by the acoustic plate 322 of Figure 9A. Figure 9C illustrates a mounting 400 of telephone receiver-transmitter assembly on a microphone-holder support. As shown herein, this telephone receiver-transmitter assembly 400 generally includes a headband 401, a left case 402 having a left cover 403 and a left cushion 409, a right case 404 having a cover 405 right and a right cushion 410, a mount 413 of microphone carrier support, and a support 440 microphone carrier. This portable microphone carrier support 440 includes first and second microphones 300 and 302 which can be arranged in a manner as previously described with reference to Figures 9A and 9B. additionally, this assembly 440 of the microphone carrier support includes a top microphone case 406, a bottom microphone 407, and a first and second microphones, 300 and 302, and a conical sleeve 408. Figure 9D illustrates a side view of the mounting 400 of the microphone. receiver-transmitter set telephone in support portaamicrófono. As shown herein, the left case 402 includes a circuit card assembly 412, which may contain the circuitry used in the processing of the acoustic signals as more fully described hereinafter, and additionally includes a mounting 411 of cable to supply signals to and from the outside or the host equipment (not shown). Figure 9E illustrates a side view of the case 404 to the right. As previously described, the first and second microphones 300 and 302 are preferably arranged within a distance b and are further arranged such that the first microphone 300 receives both speech and background noise while the second microphone receives mainly only the background noise . This background noise can originate as a pressure sound source from a location 304 as illustrated in Figures 7A and 7B. This is, as shown in them. This location 304 can be located at a distance r from a central location between the first and second microphones 300 and 302 to form an angle? between these. As a result, the distance between the first microphone 300 and the location 304 is approximately equal to the value [r- (b / 2) (without?)], And the distance between the location 304 and the second microphone is approximately equal to the value [ r + (b / 2) (without?)]. Figure 8 illustrates a differential amplifier 500 that is adapted to process signals produced by microphones 300 and 302. As shown therein, this differential amplifier 500 includes an amplifier 310, an amplifier 312 and a summation circuit 314. The signal produced by the first microphone 300 is supplied to the amplifier 310 which is adapted to essentially provide a unit gain for this signal and provide it as an output signal. This output signal is supplied to an input of the summation circuit 314. The signal produced by the second microphone 302 is supplied to the amplifier 312 which is adapted to essentially invert the received signal and to supply it to a second input of the summation circuit 314. The summing circuit 314 is adapted to add the received values together to produce a summed output signal e (Sai? Da). As you will appreciate, this output signal summed e (3aiida) represents a signal that corresponds to only substantially the user's speech. Figures 10A and 10B illustrate the differential amplifier 500 of Figure 8 in more detail. That is, Figure 10A illustrates a first array of this differential amplifier 500, and Figure 10B illustrates a second array of this differential amplifier. Each of these schematic diagrams will now be described more fully. As shown in Figure 10A, the signal produced by the first microphone 300 is supplied to an input terminal 600 and is supplied therefrom by a capacitor Cl and a resistor R to an inverting input of a differential amplifier VIA ( op-amp). The signal produced by the second microphone 302 is supplied to an input terminal 602. That input terminal 602 is coupled to a potentiometer RA, which in turn is connected to ground. The input terminal 602 is additionally coupled through a capacitor C2 and the resistors R1 and R2 to a non-inverting input of the VIA op-amp. This op-amp is adapted to operate in a differential mode and provide an output signal therefrom to a terminal 606 which in turn is coupled to the VIA op-amp conversion input. This output of the VIA op-amp is additionally supplied to potentiometer 608 which, in turn, has one end connected to ground. This potentiometer 608 is coupled through a capacitor C3 coupling to a non-inverting input of an op-amp V1B. The output of this op-amp V1B is supplied to the base of a transistor 610. The emitter of this transistor 610 is coupled to a terminal 612 which in turn is coupled through a capacitor C4 to an output terminal 614. The added signal33) is supplied from terminal 614. The collector of transistor 610 is coupled to a terminal 616 which in turn is connected to a power supply (not shown supplying a positive voltage to the circuit. to resistors R3 and R4 which are adapted to provide DC deviation The elements not specifically described are connected as illustrated in Figure 10A.

By using the circuit described above illustrated in Figure 10A, the impedance for the first and second microphones 300 and 302 is symmetrically balanced to minimize differential phase changes between the sequences. In addition, the output signal of this circuit has a relatively low impedance. Figure 10B illustrates a second alternative circuit or circuit D of the differential amplifier 500 of Figure 8 as previously described. The circuit of Figure 10B is adapted to receive energy through a source resistor from a power supply (not shown). That is, the energy to drive the circuit of Figure 10B is supplied from an energy supply having a finite output resistance R different from that supplied from an energy supply having a zero output resistance (such as that of Figure 10A). Otherwise, as will be appreciated, the circuit illustrated in Figure 10B is substantially identical to that of Figure 10A and as such, will not be further described herein. Figure 11 illustrates a phase reversal circuit that can be used in place of the circuits illustrated in Figures 10A or 10B. As illustrated therein, the circuit 700 generally includes the first and second microphones 300 and 302, the potentiometer RA of magnitude adjustment, the resistors R1 and R3 and the capacitors E which are coupled as illustrated in Figure 11. Each of the first and second microphone 300 and 302 may include a field effect transistor (FET) in which the discharge of this FET can be considered a positive (+) pole and the source of this FET can be considered a negative pole (-). The phase between this discharge and source is approximately 180 °. For example, the discharge of the same can have a phase of 180 °, while the source has a phase of 0 °. As a result, each of the first and second microphones 300 and 302 includes two terminals, i.e., a positive terminal (+) and a negative terminal (-).

In the circuit of Figure 11, the positive terminals (+) of the first and second microphones can be upper terminals thereof, while the negative terminals (-) these microphones can be the lower terminals thereof. Additionally, the magnitude adjustment potentiometer RA can be adjusted or set during initial assembly thereof or alternatively it can be adapted to be adjusted by the operator of the assembly 400 of the telephone receiver-transmitter assembly in the microphone holder support of Figure 9. The signal of exit ea-. a has a value of zero (0) when an acoustic sound having the same pressure is received by both the first and the second microphones 300 and 302. Figure 12 illustrates a circuit 800 that can be used in place of inverting circuits 700 of phase of Figure 11. In circuit 800, microphones 300 and 302 are charged in opposite manner. As a result, when the outputs thereof are added together, as when the first and second microphones receive an acoustic sound having the same pressure, the output signal e (3ai? -ta) has a value of substantially zero (0). ). The remaining portions of the circuit 800 are substantially similar to those of the circuit 700 of Figure 11 as such, will not be further described herein. In this way, any of the circuits illustrated in Figures 10A, 10B, 11 or 12 can be used in the present invention. These circuits allow calibration processing to be performed in the first and second microphones 300 and 302 which may be electrect type microphones. In addition, these circuits can be included in a printed circuit board (PC) that can be installed within the telephone receiver-transmitter assembly 400 as for example, as in the PC board 412 illustrated in FIG. Figure 9D. Alternatively, this PC board can be included in other locations of the telephone receiver-transmitter assembly 400 assembly or alternatively it can be located on the host equipment that is removed from the telephone receiver-transmitter assembly assembly 400. In this way, the present invention provides an assembly and in particular, a receiver assembly and a telephone transmitter in a microphone carrier support, which is adapted to reduce or eliminate background noise. This present apparatus uses a first and a second microphones which act as a dipole array and which can be adapted by the manufacturer or tested after manufacture, have a response to the frequency which is essentially flat over the anticipated range of operation. Furthermore, this first and second microphones are preferably arranged so that their pressure-sensitive surfaces, discussed, are arranged in mechanical degrees of 180 to each other and located in the vicinity close to it as previously described. By thus arranging the first and second microphones, a sound (in particular a background noise) originating from a source that is located at a distance substantially greater than the distance between the microphones, the sound of this source is allowed Sound is received by both microphones simultaneously. As a result, the substantial phase differential between them does not occur. Additionally, the present invention allows the amount of noise cancellation to be adjusted either during the manufacture of the present assembly of the telephone receiver-transmitter assembly on the microphone carrier support or alternatively by an operator using this assembly. The microphone in microphone holder support, for example, in Figures 7A to 13B, can be based on the principles governing the directivity patterns of omnidirectional microphones in near and far fields and the correct placement of pressure sensitive surfaces. of the microphone. The physical design of the microphone as seen in Figures 9A and 9B is the determining factor in the S / N increase. Examination of these drawings shows that the pressure sensitive surfaces of the microphone are preferably placed at mechanical degrees of 180 to each other, and provide the optimum separation of the signal going to the voice microphone and the noise microphone in the near field. This separation is a primary component in the determination of the signal in the S / N ratio. Basically, a problem in the far field is additionally vectorially, at a desired point, the sound pressures that arrive at that point from all the simple sources. The basic element of this analysis will be that in the present it is called the doublet sound receiver. The genetic situation is shown in Figure 7A and 7B. It assumes that the distance r from the two receiving microphones to the point A at which the pressure P originates is larger compared to the separation D between the two microphones. The spherical sound wave from the point above in the receiving doublet will have traveled r-b / 2 sin? during mee 1 and r + b / 2 sen? during ic 2. If r >; > b, the distance traveled by the spherical wave is r, and the output of each receiving microphone is equal. If the summed outputs of the two microphones are zero as in Figure 8, then the associated scale factors are equal. If its associated scale factors are not equal, the phase and / or amplitude, the output will not be zero. It can be obtained electrically and e- performs amplitude adjustment, but it is impossible at all frequencies. phasing. The requirement for phase adjustment is not required because reproducibility is inherent in the manufacture of the microphones and provides phase-out outputs frequently. The microphones described are the dual source and doublet sound and are similar to the theory of dipoles. Also, if the space b between the microphones is small (b < <) compared to the wavelengths at any distance r, the two microphones coalecen essentially and the output at any angle? it will be zero to match the scale factors (magnitude / phase) at any frequency. If b is not larger than r, the phase relationship between the two microphones to an incoming sound wave is: where b = space between mic sensor and noise m f = frequency at hz v = sound velocity in / sec 0 = phase change in a specific sequence 0 = 360 bf (1) V "As can be seen from equation (1), this phase relationship is the theoretical limit for the crossing of fields near and far from the microphone of noise cancellation As the frequency changes in a fixed b, the phase changes, ie: at 0 = 90, there is no total cancellation.This phase change, in the absence of the acoustic screens can be a governing factor in the width of cancellation band The embodiment of the invention of Figures 7A to 13B can be used in the far field design of the microphones for cancellation.The reduction of the effect of b, e performed by the use of an acoustic design that has to minimize to zero, dimension b, in Figure 9A, and that odifica to reduce the thickness of the as is, in Figure 9B. Both designs use the relationship between b and r (ie: b << r). Furthermore, the microphone microphone / system microphone of the invention is optimally defined by the location of the microphone pressure surfaces, preferably 180 ° in the case of the microphone in the microphone holder support, but cancellation will occur due to the present subtraction system in all cases. The angles. Actually, when the pressure surfaces of the microphone are at zero degrees with respect to each other, the total cancellation could theoretically be obtained but voice would not be transmitted. The inventive system may depend on the directivity patterns of the microphones in the near and far fields, the orientation of their pressure-sensitive surfaces, and the electrical subtraction processes. Typical circuits that = e may be used for subtraction are shown in Figures 10A-12. In Figure 10A and 10B, the circuit is similar to the circuits used in the telephone modes described above with respect to Figures 1 to 5. In these, the U1A circuit is used for the subtraction and U1B is used for the connection in exit waterfall. The phase reversal circuit is shown in Figure 11. This circuit will provide two signals at points A and B, 180 degrees out of phase with identical sound signals on microphones 1 and 2, if the microphones are adapted parts ( by manufacturing). This output can be adjusted to adapt the amplitude at a reference frequency by the adjustment of RA in conjunction with the capacitor C. The signal in e3a? .da is the canceled output of noise when the microphones are placed in the appropriate mechanical environment mentioned previously . The analysis of the circuit of Figure 11 can be shown to provide the following information. The output in A is in the source of internal FET contained within a microphone (preferably electret) such that its output at an electric angle of 0 degrees with the input pressure signal, while the output in B is from the discharge of the internal FET contained within the electret microphone its output is at an electric angle of 180 degrees with the input pressure signal. When these two far field signals are added together in a voltage mode, the output is 0 if the amplitude is adjusted by the RA potentiometer at a reference frequency and the magnitude response is flat across the sequence spectrum. In the circuit in Figure 12, the oppositely charged microphones provide two signals in A and B, 180 degrees out of phase with identical sound signals in the microphones 1 and 2. This phase inversion is achieved by virtue of the opposite charge during the manufacture of the condenser plates of the electret microphones. All other characteristics are as previously stated for the phase inversion circuit. Circuits of the type found in Figures 11 and 12 provide electrical subtraction without the need to use an op-amp. The microphone telephone receiver-transmitter assembly device in the microphone carrier support of the invention (eg, Figures 7A-13B) can provide computer voice recognition. The telephone microphone receiver-transmitter assembly in the microphone holder support provides superior rejection of unwanted background noise and excellent voice response. The microphone telephone receiver-transmitter set in a microphone holder can be configured to be compatible with all "Sound Blaster" audio cards. All other audio card interfaces are also easily adaptable. The telephone microphone receiver-transmitter set in the microphone holder support of the invention (eg, Figure 7A-13B) coupled with the latter in high-quality speech recognition programming elements improve the control of the computer with speech at a level of user friendliness and reliability equal to the keyboard and the mouse. In the present invention, speech recognition is no longer confined to closed-door, quiet offices, but can be used in noisy real-world environments, such as hotel lobbies, hospital emergency rooms, manufacturing facilities and noisy office areas. In this way, the telephone microphone receiver-transmitter assembly in a microphone holder can be interconnected with computers, telephones or other equipment in the real world, or the microphone in a microphone holder support (without the receiver-transmitter telephone set) can be used in several applications of speech recognition. The telephone receiver-transmitter assembly in the microphone holder support of the invention performs to be sensitive to a distance from the sound source. Arbitrary sound fields that demand more than a few inches away from the microphone are substantially canceled by up to 30 dB (3200%). The telephone microphone receiver-transmitter assembly in the microphone holder support of the invention is preferably connected to a 3-meter cable terminating in a 3.5 mm miniature male plug (not shown). To connect it to the sound card, the user simply inserts the miniature male plug into the microphone input jack of the sound card (not shown). The telephone microphone receiver-transmitter assembly in the microphone holder support of the invention is then placed on the user. The telephone receiver-transmitter assembly preferably has two features to assist in microphone placement in the proper position for reliable speech recognition: (1) adjustable nose pads on both right and left sides and (2) a flexible microphone support, adjustable. The microphone at the end of the flexible microphone holder support preferably has a white or coded dot with another color indicating the voice side of the microphone that must be adjusted directly to the face of the mouth. The appropriate close conversion in the invention is useful for the exact operation. Preferably, the distance between the mouth to the microphone should be in the range of about 0.63 cm (1/4 inch) to about 1.9 cm (3/4 inch), preferably between about 1.27 cm (1/2 inch) or less. For use with the "Sound Blaster ™", it is important to disable automatic gain control (AGC) on the sound card before using the present invention in noise cancellation applications. If the AGC is ON, it will destroy the noise canceling properties of the microphone by automatically increasing the input audio volume when the user is not speaking. The AGC can be disabled on the Sound Blaster ™ cards by running the Creative Mixer® and pressing the AGC program control under "recording settings ...". The input audio gain is easily adapted to the objective application using the Creative Mixer "* R program. The test of the telephone microphone receiver-transmitter set of the invention can be easily performed by using the production recording features of the Creative program. Labs Wave Studio ". Figures 13A and 13B are active noise cancellation curves of the microphone in a microphone holder support in a receiver-transmitter telephone set mode with Figure 13A, upper line, representing the response in the near field in Figure 13A, bottom line , which represents the far field response. In Figure 13B, the upper line represents the close conversation response and the background line represents the response of the background noise. Typical specifications for the microphone telephone receiver-transmitter package in a microphone holder include: Frequency response: from 20 Hz to 10 kHz Output impedance: Low impedance (able to drive 560 ohm) Sensitivity: -47 dB ± 2 dB (0 dB ± 1 v / Pa 1 kHz, 5V) Operating voltage: 2V to 10V Current: < 1 mA (5V power supply) Electrical S / N: 60 dB (minimum) Noise cancellation: See Figure 13B Cable type: Non-separable, protected Cable length: 3000 ± 50 mm Plug type: male, miniature, stereo, 3.5 mm Weight: 56 gm (without cable) Using the interpretation of speech intelligibility AI and ANSI S3.5-1969, a microphone telephone receiver-transmitter set in the microphone holder support of the invention and a normal, dynamic noise cancellation microphone (prior art) and the results were tested. They were as follows: INDEX OF JOINTS: MICROPHONE IN PORTAMICRÓFONO SUPPORT OF THE INVENTION INDEX OF JOINTS: DYNAMIC, NORMAL NOISE CANCELLATION MICROPHONE (PREVIOUS TECHNIQUE) The interpretation of speech intelligibility using AI and ANSI S3.5-1969 shows a level of accuracy of 93 % for the present invention against a level of accuracy of only 45% for the normal, dynamic noise canceling microphone. A comparison of these data reflects a reduction in the error ratio of approximately 8: 1 by the present invention (i.e., 45% AI by the normal dynamic microphone, 93% noise cancellation AI by the present invention). Additionally, additional AI is expected when the constants that are active up to 50 cycles and below are corrected. The literal evaluation of AI calculation states that for every 100 spoken words, the present invention will make 7 errors, and the normal dynamic mic will make 55 errors. All methods and calculations were collected and performed at Andrea Electronics Corporation. Both microphone systems were tested at Andrea Electronics Corporation under the same conditions. Additionally, although the embodiments described above of the present invention have been described for use with telephone receiver-transmitter assemblies and similar microphone-holder microphones, the invention is not limited and can be used with numerous different devices such as intercom systems, telemetry , acoustic surveillance microphones, directional microphones and so on. Additionally, the invention can be used in speech recognition and / or verification systems such as systems for access to physical media, computer programs, computers or automatic computing machines and the like. Additionally, the present invention can be used with processing devices that operate in accordance with predetermined processing algorithms, as described in U.S. Patent No. 5,251,263, which has a common transferee with the present application, and which is incorporated by this mode by reference. However, it is not believed to be necessary for the invention. Additionally, while preferred embodiments of the present invention and modifications thereof have been described in detail herein, it should be understood that the invention is not limited to those precise embodiments and modifications, and that other modifications and variations may be made with a one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims (11)

1. A noise reduction apparatus, characterized in that it comprises: a housing having a first microphone means for receiving a first acoustic sound composed of speech originating from an operator operating the apparatus and background noise, and for converting the first acoustic sound at a first signal, and a second microphone means arranged at a predetermined angle 0 with respect to the first microphone means to receive a second acoustic sound composed of substantially the background noise and to convert this second acoustic sound to a second one. signal; and a subtracting means for subtracting the second signal from the first signal to obtain a signal that substantially represents speech.

2. The noise reduction apparatus according to claim 1, characterized in that at least the first and second microphone means include a plurality of microphones.

3. The noise reduction apparatus according to claim 1, characterized in that the first and / or second microphone means comprise a plurality of microphones and the outputs of the first and / or second microphone means comprise a weighted sum of several output voltages of microphone that are weighted according to a desired function.

4. The noise reduction apparatus according to claim 3, characterized in that the desired function is a gradient search algorithm.

5. A microphone apparatus for reducing background noise, the apparatus is characterized in that it comprises: a housing; a first microphone having a first pressure sensitive surface and arranged within the housing to receive a first acoustic sound composed of speech originating from an operator operating the apparatus and background noise, the first microphone to convert the first sound acoustic at a first signal; a second microphone having a second pressure-sensitive surface and arranged within the housing to receive a second acoustic sound composed of substantially the background noise, the second microphone that converts the second acoustic sound to a second signal, the second surface sensitive to the pressure that is arranged at a predetermined angle with respect to the first pressure-sensitive surface; and a means for subtracting the second signal from the first signal to obtain a signal that substantially represents speech.

6. A microphone apparatus according to claim 5, characterized in that the predetermined angle is substantially 180 degrees.

7. A microphone apparatus according to claim 6, characterized in that the first and second sensitive surfaces are located at less than a predetermined amount with respect to each other.

8. A microphone apparatus according to claim 7, characterized in that the predetermined amount is approximately 0.63 of an inch.

9. The noise reduction apparatus according to claim 1, characterized in that the predetermined angle 0 is located within a range of about 30 degrees to about 60 degrees.

10. The noise reduction apparatus according to claim 9, characterized in that the first microphone means is arranged in the housing such that an angle? formed between a plane passing through a portion of the first microphone means receiving the first acoustic sound and a speech input address less than about 35 degrees.

11. The noise reduction apparatus according to claim 10, characterized in that the second microphone means is arranged in the housing such that an angle ß formed between an axis normal to the receiving portion of the second microphone means and the input direction of the microphone. speech is approximately equal to [(90 -?) + 0] degrees.