JP2011234213A - Sound source direction estimation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound source direction estimation apparatus capable of precisely estimating the direction of a sound source even there is a fluctuation with the sensitivity characteristics of a microphone.SOLUTION: A sound source direction estimation apparatus 20 allows audible and prescribed range of frequency components in each of the electric signals output by microphones 1 to 4 and amplified by amplifiers 5 to 8 to pass through each of BPF 21 to 24, and allows a sound source direction operation part 27 to estimate the direction of a sound source based on the frequency components passed through each of BPF 21 to 24. Then, the adjustment of amplification degree to reduce the difference of sensitivity characteristics of frequencies in the prescribed range is enabled by allowing an amplification adjustment part 26 to mutually adjust the amplification degree in generating frequency components from the electric signals with respect to each of the microphone 1 to 4, thereby gaining the frequency components with reduced sensitivity characteristics fluctuations for each of the microphones 1 to 4 for estimating the sound source direction precisely.

Description

  The present invention relates to a sound source direction estimating apparatus.

  2. Description of the Related Art Conventionally, as shown in Patent Document 1 below, a control system applied to a video conference or the like, in which an imaging device and a plurality of microphones are provided in a housing, and a speaker's voice is collected by each microphone. There is known a system that converts an electric signal and calculates the direction of a speaker (sound source) using the converted electric signal. In this system, a speaker can be imaged by controlling the angle of the imaging device so that the imaging device is directed in the calculated direction.

JP 2007-214753 A

  In a system that calculates the direction of a speaker using a plurality of microphones as described above, the electric signal output from each microphone is usually amplified by an amplifier, and the direction of the sound source is calculated using the output value of the amplified electric signal. To do. However, each microphone has some variation in sensitivity characteristics due to individual differences. Therefore, in order to reduce variations in sensitivity characteristics among individual microphones, for example, before the system is shipped from the factory, it is common to adjust the amplification degree of the amplifier so as to match the output value with respect to the reference sound source.

  However, with the conventional technology, although the output value can be adjusted according to a certain frequency by adjusting the amplification factor of the amplifier, the sensitivity characteristics of individual microphones vary depending on the frequency. When the frequency of the sound input to is different from the frequency of the reference sound source at the time of adjustment, as a result, an error occurs in the output value of each microphone. For this reason, it has been difficult to calculate the direction of the sound source with high accuracy.

  An object of the present invention is to provide a sound source direction estimation apparatus that can accurately estimate the direction of a sound source even when the sensitivity characteristics of microphones vary.

  A sound source direction estimating apparatus according to the present invention includes a plurality of microphones that input sound generated by a sound source and convert the sound into an electric signal, an amplifying unit that amplifies an electric signal output from each of the plurality of microphones, and an amplifying unit A band-pass filter that passes a predetermined range of frequency components within the audible range in each electric signal amplified by the sound source, and a sound source direction estimating unit that estimates the direction of the sound source based on the frequency component that has passed through the band-pass filter. The amplification degree when generating the frequency component from the electrical signal corresponding to the plurality of microphones is configured to be adjustable.

  According to the sound source direction estimating apparatus according to the present invention, the electric signal output from each of the plurality of microphones is amplified by the amplifying means, and the frequency component in a predetermined range in the audible range in each of the amplified electric signals is a bandpass filter. Pass through. The sound source direction estimating means estimates the direction of the sound source based on the frequency component that has passed through the bandpass filter. Here, since the amplification degree when generating the frequency component from the electrical signal corresponding to a plurality of microphones is configured to be mutually adjustable, even if the sensitivity characteristics of the individual microphones differ depending on the frequency, a predetermined range It is possible to adjust the amplification degree so as to reduce the difference in sensitivity characteristics at the frequency of. Therefore, a frequency component in which variations in sensitivity characteristics for each microphone are reduced can be obtained. Since the direction of the sound source is estimated by the sound source direction estimating means using the frequency component in which the variation is thus reduced, the direction of the sound source can be estimated with high accuracy.

  Here, it is preferable to provide an amplification degree adjusting means for adjusting the amplification degree of the frequency component corresponding to at least one of the frequency components that have passed through the bandpass filter.

  According to such a configuration, since the amplification degree of the frequency component corresponding to at least one microphone among the frequency components that have passed through the bandpass filter is adjusted by the amplification degree adjusting means, the frequency extracted by the bandpass filter The degree of amplification can be adjusted so as to reduce the difference in sensitivity characteristics among the components, and the above-described effect of improving the direction estimation accuracy is preferably exhibited.

  In addition, it is preferable that the amplifying unit includes an amplification degree adjusting unit that adjusts an amplification degree of the electric signal output from at least one microphone among the electric signals output from the plurality of microphones.

  According to such a configuration, the amplification unit can adjust the amplification degree of the electric signal output from at least one microphone among the electric signals output from the plurality of microphones by the amplification degree adjustment unit, It is possible to adjust the amplification degree so as to reduce the difference in sensitivity characteristics at the frequency of. Then, by extracting a frequency component in a predetermined range using a bandpass filter, a frequency component in which variation in sensitivity characteristics for each microphone is reduced is obtained, and the above-described effect of improving the direction estimation accuracy is preferably exhibited.

  Here, the plurality of microphones are embedded in a housing in which an opening for capturing sound is formed, and it is preferable to input sound that propagates through the opening into the housing.

  According to such a configuration, the sound generated at a position shifted by a certain angle with respect to the direction line connecting the opening and the microphone is diffracted near the opening and reaches the microphone. Although sound is attenuated by this diffraction, the angle at which the sound source is located and the sound attenuation amount have a correlation according to the frequency of the sound. That is, for a sound with a low frequency, the amount of attenuation is small even when the angle is large, but for a sound with a high frequency, the amount of attenuation increases as the angle increases. A frequency component in a predetermined range in each electric signal amplified by the amplifying means passes through the bandpass filter, so that a frequency component in a band having a high correlation with the angle at which the sound source is located can be extracted. Since the direction of the sound source is estimated using the frequency component that has passed through the bandpass filter, the direction of the sound source can be accurately determined even when a non-directional microphone that does not have directivity is used. Can be estimated.

  According to the present invention, the direction of a sound source can be accurately estimated even when the sensitivity characteristics of microphones vary.

1 is a perspective view of a video conference camera to which a sound source direction estimating device according to an embodiment of the present invention is applied. 2A is a cross-sectional view of the position including the opening in the video conference camera of FIG. 1, and FIG. 2B is a side view of the cylindrical body in FIG. 2A viewed from the axial direction. . It is a block diagram which shows the function structure of the camera for video conferences of FIG. It is a figure for demonstrating adjustment of the amplification degree in the amplification degree adjustment part in FIG. It is a schematic diagram which shows the angle which the direction of a sound source makes with respect to the axis line of a cylindrical body. FIG. 6A is a diagram showing the position of the sound source with respect to the video conference camera, and FIG. 6B is a diagram showing the sensitivity characteristics of the microphone in the case of FIG.

  Hereinafter, a sound source direction estimating apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description, a case where the sound source direction estimating device is applied to a video conference camera will be described.

  As shown in FIGS. 1 to 3, the video conference camera A is installed at a position surrounded by, for example, a plurality of participants participating in the video conference, and speaks (hereinafter referred to as “speaker”). The video of the speaker is acquired by directing the camera 35 in that direction. The video conference camera A can communicate with the other party's video conference system via a network.

  The video conference camera A has a substantially cylindrical shape with a diameter of about 10 cm placed on a table or the like, and a resin-made first housing 10a, and an axis (not shown) arranged in the vertical direction along the axis of the first housing 10a. And a second housing 10b made of resin having a substantially rectangular parallelepiped shape that is rotatable about the axis of the first housing 10a. The camera 35 is housed in the second housing 10b.

  On the side surface of the first housing 10a, four circular openings 11 to 14 are formed at the same height and spaced apart by 90 ° in the circumferential direction. Each opening 11-14 is a hole for taking in the voice of the speaker uttered around the video conference camera A into the first housing 10a, and has an inner diameter of about 8 mm.

  Four cylindrical bodies 16 to 19 having a cylindrical shape extending in the radial direction of the first casing 10a from the openings 11 to 14 into the first casing 10a are fixed to the inner surface side of the first casing 10a. . The inner diameter of each cylindrical body 16-19 is about 8 mm, and the inner peripheral surface of each opening 11-14 and the inner wall surface of each cylindrical body 16-19 are substantially flush. Each cylindrical body 16-19 forms propagation paths B1-B4 on a cylindrical shape having a diameter of about 8 mm inside thereof. That is, each propagation path B1-B4 is formed so that it may extend horizontally in the radial direction of the 1st housing | casing 10a toward the inside of the 1st housing | casing 10a from each opening 11-14. In addition, each opening 11-14 means the hole formed in the outer wall of the 1st housing 10a, and each cylindrical body 16-19 and each propagation path B1-B4 are included in each opening 11-14. I can't.

  Furthermore, four cylindrical microphones (hereinafter referred to as “hereinafter referred to as“ microphones ”) are formed at the ends of the cylindrical bodies 16 to 19 located on the center side of the first casing 10a so that the front faces are parallel to the openings 11 to 14, respectively. 1-4) are embedded. Each of the microphones 1 to 4 is an omnidirectional electric condenser microphone having a diameter of about 7 mm and a thickness of about 4 mm and capable of collecting sound only on the front side. Each of the microphones 1 to 4 incorporates diaphragms 1a to 4a made of a circular diaphragm having a diameter of about 5 mm. The shortest distance from each opening 11-14 to the front surface of each microphone 1-4 is about 10 mm, which is longer than the inner diameter of each opening 11-14. Moreover, as above-mentioned, the internal diameter (cross section) of propagation path B1-B4 is larger than the diaphragms 1a-4a (refer FIG. 2). Thereby, the sound passing through the propagation paths B1 to B4 is surely transmitted to the diaphragms 1a to 4a. Spacers (not shown) are disposed between the microphones 1 to 4 and the inner wall surfaces of the cylindrical bodies 16 to 19.

  With such a configuration, the video conference camera A has a mechanism in which the voice of the speaker in the conference is input to the microphones 1 to 4 through the openings 11 to 14 and the propagation paths B1 to B4. Then, the diaphragms 1a to 4a are vibrated by the sound input to the microphones 1 to 4, and the sound is converted into an electrical signal according to the vibration, and the electrical signal is output from the microphones 1 to 4 to the amplifiers 5 to 8. (See FIG. 3). In addition, it is the structure which the sound outside the 1st housing 10a does not propagate to the internal space S of the back side of the microphones 1-4.

  As shown in FIG. 3, the video conference camera A has a function of estimating the direction of the speaker by performing a predetermined process based on the sound input to the microphones 1 to 4. Specifically, the video conference camera A receives the electric signals output from the microphones 1 to 4, and amplifies the input electric signals, four amplifiers (amplifying means) 5 to 8, and each amplifier 5. Bandpass filters (hereinafter referred to as “BPFs”) 21 to 24 that pass a predetermined range of frequency components in each electric signal amplified by ˜8, and each frequency component that passed through each BPF 21 to 24 is analog-digital (Analog) -Digital) AD conversion unit 25 for conversion, and amplification degree adjustment unit 26 for adjusting the amplification degree of the frequency component corresponding to at least one of the microphones 1 to 4 among the frequency components digitally converted by the AD conversion unit 25 A sound source direction calculation unit (sound source direction estimation means) 27 that estimates the direction of the sound source using the frequency component output from the amplification degree adjustment unit 26, a histogram registration unit 28, and a sound source method And a direction re-calculation unit 29.

  The amplifiers 5 to 8 are connected to the microphones 1 to 4, respectively, and amplify the electrical signals output from the microphones 1 to 4 by an amplifier circuit. Each amplifier 5-8 outputs the amplified electric signal to each BPF 21-24.

  Each BPF 21-24 receives the electrical signal output from each of the amplifiers 5-8, and, for example, by blocking frequency components of 2.5 kHz or less and 6.5 kHz or more from the input electrical signal, 2.5 kHz Pass frequency components in the range of ~ 6.5 kHz. The range of the frequency passed by each BPF 21 to 24 is a predetermined range in the audible range. Each BPF 21 to 24 is configured by combining a high-pass filter that cuts off frequency components of 2.5 kHz or less and a low-pass filter that cuts off frequency components of 6.5 kHz or more.

  The AD conversion unit 25 converts each frequency component that has passed through each of the BPFs 21 to 24 from an analog signal to a digital signal. The AD conversion unit 25 may have a function of identifying which one of the BPFs 21 to 24 is a frequency component, or a plurality of AD conversion units 25 may be provided corresponding to the amplifiers 5 to 8. The AD conversion unit 25 generates a frequency component converted into a digital signal, and outputs the frequency component to the amplification adjustment unit 26 together with a signal indicating which of the microphones 1 to 4 corresponds to the frequency component. To do.

  The amplification degree adjustment unit 26 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The amplification degree adjustment unit 26 receives the frequency component output from the AD conversion unit 25, and adjusts the amplification degree of the frequency component corresponding to the microphone whose sensitivity characteristic is deviated from other microphones among the input frequency component. To do. In other words, the amplification degree adjustment unit 26 can mutually adjust the amplification degree when generating the frequency component from the electric signal corresponding to each of the microphones 1 to 4.

  More specifically, the sensitivity characteristics of the microphones 1 to 4 vary depending on individual differences. FIG. 4 is a diagram for explaining the adjustment of the amplification degree in the amplification degree adjustment unit 26. In FIG. 4, the horizontal axis indicates the frequency, and the vertical axis indicates the relative value of the output value of the microphone with respect to the reference value (that is, sensitivity) when a certain reference sound is generated from a position at a certain distance in front of the microphone. ). In the example shown in FIG. 4, the microphone 1 and the microphone 2 have different sensitivity characteristics depending on the frequency. That is, the relative value of the microphone 1 decreases as the frequency increases, whereas the relative value of the microphone 2 increases as the frequency increases. In other words, the microphone 1 has high sensitivity at a low frequency, and the microphone 2 has high sensitivity at a high frequency.

  In this case, the amplification degree adjusting unit 26 adjusts the amplification degree of the microphone 2 so that the sensitivities in the range of 2.5 kHz to 6.5 kHz that are passed by the BPFs 21 to 24 are substantially equal between the microphone 1 and the microphone 2. . The amplification degree adjustment by the amplification degree adjustment unit 26 is performed by multiplying the frequency component output from the AD conversion unit 25 by a constant coefficient corresponding to the difference in sensitivity characteristics. More specifically, a coefficient of 1 or more is used when increasing the amplification degree, and a coefficient of less than 1 is used when decreasing the amplification degree. This coefficient is appropriately set according to each of the microphones 1 to 4 by a test using a reference sound before being shipped from the factory, for example, and stored in the amplification degree adjustment unit 26. As described above, since the sensitivity characteristics of the microphones 1 to 4 can be made uniform by a simple calculation by the amplification degree adjustment unit 26, the accuracy of the direction estimation of the sound source can be improved, and the speaker can be photographed by the video conference camera A. Is surely done.

  The adjustment of the amplification degree by the amplification degree adjustment unit 26 is not limited to the case of multiplying by a coefficient, and may be a technique that can reduce variations in sensitivity of the microphones 1 to 4 in a frequency range that is allowed to pass by the BPFs 21 to 24. Any method may be used. FIG. 4 shows an example in which the microphone 1 and the microphone 2 have sensitivity characteristics that change with a certain tendency according to the frequency, but actually the sensitivity characteristics of the microphones vary irregularly with respect to the frequency. Even in such a case, variations in sensitivity characteristics of the microphones 1 to 4 are reduced by extracting frequency components in a predetermined range in the BPFs 21 to 24 and adjusting the amplification degree in the amplification degree adjustment unit 26. can do.

  The amplification degree adjustment unit 26 corresponds to a frequency component corresponding to a microphone whose amplification degree is adjusted and a frequency component corresponding to a microphone whose amplification degree is not adjusted, and each frequency component corresponds to any of the microphones 1 to 4. It outputs to the sound source direction calculating part 27 with the signal which shows whether it is a frequency component.

  The sound source direction calculation unit 27, the histogram registration unit 28, and the sound source direction recalculation unit 29 are configured by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The sound source direction calculation unit 27, the histogram registration unit 28, and the sound source direction recalculation unit 29 estimate the speaker direction by calculating the speaker direction based on the frequency component output from the amplification degree adjustment unit 26. To do.

  Specifically, the sound source direction calculation unit 27 compares output values (sound levels) of frequency components corresponding to the microphones 1 to 4 based on the frequency components output from the amplification degree adjustment unit 26. Thus, the direction of the sound source from which the sound is emitted is calculated. As the calculation process of the direction of the sound source in the sound source direction calculation unit 27, a known technique can be used. The direction of the sound source in the video conference camera A is positive in the clockwise direction when viewed from above the first housing 10a with reference to a predetermined position in the circumferential direction of the first housing 10a (for example, the center position of the opening 11). It is expressed as an angle (0 ° to 360 °). The calculation of the direction of the sound source by the sound source direction calculation unit 27 is executed every predetermined time, for example, every 40 milliseconds.

  As described above, the microphones 1 to 4 are embedded in the first casing 10a through the openings 11 to 14 at a predetermined length (for example, about 10 mm). The sound that reaches is attenuated by diffraction. For example, as shown in FIG. 5, if the direction in which the sound source is located is shifted by an angle θ with respect to the direction line connecting the center of the microphone 1 and the center of the opening 11 (that is, the axis of the cylindrical body 16), Sound that is high is attenuated by the angle θ shift and reaches the microphone 1. Since each BPF 21-24 passes a frequency component of 2.5 kHz or more, an output value affected by the angle is input to the sound source direction calculation unit 27, and the output values corresponding to the microphones 1 to 4 are compared. Thus, the calculation of the direction of the sound source in the sound source direction calculation unit 27 is performed with high accuracy. The sound source direction calculation unit 27 outputs the calculated direction of the sound source every predetermined time to the histogram registration unit 28.

  The histogram registration unit 28 receives the direction of the sound source output from the sound source direction calculation unit 27 and sequentially stores the input direction of the sound source. In storing the direction of the sound source by the histogram registration unit 28, the latest data is always overwritten on the oldest data. Then, the histogram registration unit 28 classifies the stored sound source directions into 20-degree angular ranges in increments of 20 °, and generates a histogram according to the classification result. The histogram registration unit 28 outputs the generated histogram to the sound source direction recalculation unit 29.

  The sound source direction recalculation unit 29 receives the histogram output from the histogram registration unit 28, and converts the frequency in the angle range where the frequency is maximum in the input histogram and the frequency in the angle range near the angle range. The direction of the sound source is recalculated by obtaining the average value of the angle range based on it. The sound source direction recalculation unit 29 outputs the recalculated sound source direction to the motor control unit 31 as the speaker direction.

  In this way, the sound source direction calculation processing is performed by the sound source direction calculation unit 27, the histogram registration unit 28, and the sound source direction recalculation unit 29, and the direction of the speaker is estimated. As shown in FIGS. 1 and 3, in the video conference camera A, the first casing 10a, openings 11 to 14, cylindrical bodies 16 to 19, microphones 1 to 4, amplifiers 5 to 8, BPFs 21 to 24, AD conversion The sound source direction estimating device 20 is configured to include a unit 25, an amplification degree adjusting unit 26, a sound source direction calculating unit 27, a histogram registration unit 28, and a sound source direction recalculating unit 29.

  Further, as shown in FIG. 3, the video conference camera A has a function of directing the camera 35 in the direction of the sound source estimated by the sound source direction estimating device 20 and acquiring the video of the speaker by the camera 35. Specifically, the videoconferencing camera A is controlled by the motor control unit 31 that controls the motor drive unit 32 based on the direction of the sound source output from the sound source direction recalculation unit 29 and the motor controlled by the motor control unit 31. A motor drive unit 32 that drives the motor 33, a motor 33 that is driven by the motor drive unit 32 to apply a rotational force to the camera rotation mechanism 34, and is connected to the motor 33 to rotate the camera 35 together with the second casing 10b by rotation. A camera rotation mechanism 34, a camera 35 that acquires video, a video processing unit 36 that performs video processing on video data acquired from the camera 35, and a data transfer unit that transfers video data processed by the video processing unit 36 37 and a network communication unit 38 that transmits the video data transferred by the data transfer unit 37 to the network.

  Next, the operation of the video conference camera A will be described. In the following description, as shown in FIG. 6A, a case where a voice is emitted from a speaker located at 45 ° opposite to the opening 13 and the opening 14 at an equal distance from the opening 11 and the opening 12. This will be described as an example. As shown in FIG. 6B, the peak values of the output values of the frequency components corresponding to the microphones 1 to 4 are between 2.5 kHz to 10 kHz. More specifically, the output values seen between 2.5 kHz and 10 kHz are the same for the microphones 1 and 2, and are attenuated more than the microphones 1 and 2 for the microphones 3 and 4. On the other hand, the output values seen at 2.5 kHz or less are substantially equal for the microphones 1 to 4.

  In the sound source direction estimation apparatus 20, the frequency components in the range of 2.5 kHz to 6.5 kHz are allowed to pass by blocking the frequency components of 2.5 kHz or less and 6.5 kHz or more by the BPFs 21 to 24. In the example shown in FIG. 6B, components in the range of 2.5 kHz to 6.5 kHz that are greatly affected by diffraction are extracted as output values. Further, the amplification degree adjustment unit 26 adjusts the amplification degree of the frequency component corresponding to at least one of the microphones 1 to 4 so that the sensitivities of the microphones 1 to 4 are substantially equal in the range of 2.5 kHz to 6.5 kHz. Is done. Then, the direction of the sound source is calculated using each frequency component output from the amplification degree adjustment unit 26, and the sound source is estimated to be at a 45 ° position. The sound source direction estimating device 20 outputs a signal indicating 45 ° to the motor control unit 31.

  The motor control unit 31 inputs a signal indicating 45 ° output from the sound source direction estimating device 20, controls the motor driving unit 32 to drive the motor 33, and the camera 35 faces in the 45 ° direction. The camera 35 is rotated together with the second casing 10b by the camera rotation mechanism 34. Note that the turning control of the camera 35 by the motor control unit 31 is executed using the average value of the direction of the sound source within the certain range when the direction of the sound source within the certain range is input continuously for a predetermined time. May be.

  The camera 35 acquires a front video and generates video data indicating the acquired video. The camera 35 outputs the generated video data to the video processing unit 36. The video processing unit 36 receives the video data output from the camera 35, performs video processing on the input video data, and outputs the video data after the video processing to the data transfer unit 37. The data transfer unit 37 receives the video data output from the video processing unit 36 and transfers the input video data to the network communication unit 38. Then, the network communication unit 38 transmits the video data transferred from the data transfer unit 37 to the other party's video conference system via the network.

  According to the sound source direction estimating apparatus 20 of the present embodiment, the electrical signals output from the microphones 1 to 4 are amplified by the amplifiers 5 to 8, and the frequency components in a predetermined range within the audible range in each of the amplified electrical signals. Passes through each BPF 21-24. The sound source direction calculation unit 27 estimates the direction of the sound source based on the frequency components that have passed through the BPFs 21 to 24. Here, since the amplification degree when generating the frequency component from the electrical signal corresponding to each microphone 1 to 4 is configured to be mutually adjustable by the amplification degree adjustment unit 26, the sensitivity characteristics of each microphone 1 to 4 are configured. Even when the frequency varies depending on the frequency, it is possible to adjust the amplification degree so as to reduce the difference in sensitivity characteristics in a predetermined range of frequencies. Therefore, a frequency component with reduced variation in sensitivity characteristics for each microphone 1 to 4 is obtained, and the direction of the sound source is estimated by the sound source direction calculation unit 27 using the frequency component with reduced variation. Can be accurately estimated.

  Furthermore, a frequency component in a predetermined range in each electric signal amplified by each amplifier 5 to 8 passes through the BPF 21 to 24, thereby extracting a frequency component in a band having a high correlation with the angle at which the sound source is located. Since the direction of the sound source is estimated using the frequency components that have passed through each of the BPFs 21 to 24, the direction of the sound source can be accurately estimated even when the omnidirectional microphones 1 to 4 are used. Can do.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the case where the amplification degree of the frequency component corresponding to at least one microphone among the frequency components that have passed through each of the BPFs 21 to 24 is adjusted by the amplification degree adjustment unit 26 is described. May be provided in each amplifier 5-8. That is, each amplifier 5-8 may have an adjustment mechanism (for example, adjustment knob) for adjusting the amplification degree of the electric signal output from each microphone 1-4 as an amplification degree adjustment means. In this case, by adjusting the amplification degree of the electrical signal output from at least one microphone among the electrical signals output from each microphone 1 to 4 by the adjustment mechanism, each microphone 1 to 4 variations in sensitivity characteristics can be reduced.

  Moreover, although the said embodiment demonstrated the case where the four microphones 1-4 were provided, the installation number of microphones may be 2 or 3, and may be 5 or more. In addition, the range of frequencies passed by the BPFs 21 to 24 can be set as appropriate within the audible range according to the characteristics of the microphone. By setting the range within the audible range in this way, the sound source direction estimating device can be applied to sound sources of all frequencies that can be heard by humans, and versatility as a sound source direction estimating device is enhanced.

  Furthermore, in the above-described embodiment, the case where the sound source direction estimating device 20 is applied to the video conference camera A has been described. However, the direction of the sound source is estimated using a plurality of microphones, and the estimated direction of the sound source is used. If it is an apparatus, it will not be restricted to this. For example, the sound source direction estimating apparatus of the present invention can be applied to a monitoring camera or the like that detects abnormal sound and reflects the direction of the sound source in which the abnormal sound has occurred.

  DESCRIPTION OF SYMBOLS 1-4 ... Microphone, 5-8 ... Amplifier (amplification means), 10a ... Housing, 11-14 ... Opening, 20 ... Sound source direction estimation apparatus, 21-24 ... BPF, 26 ... Amplification degree adjustment part (Amplification degree adjustment means) 27... Sound source direction calculation unit (sound source direction estimation means).

Claims (4)

A plurality of microphones for inputting sound generated by a sound source and converting the sound into an electrical signal;
Amplifying means for amplifying the electrical signal output from each of the plurality of microphones;
A bandpass filter that passes a predetermined range of frequency components within the audible range in each of the electrical signals amplified by the amplification means;
Sound source direction estimating means for estimating the direction of the sound source based on the frequency component that has passed through the band-pass filter,
A sound source direction estimating apparatus, wherein the amplification degree when generating the frequency component from the electrical signal corresponding to the plurality of microphones is adjustable.   The sound source direction estimating apparatus according to claim 1, further comprising: an amplification degree adjusting unit that adjusts an amplification degree of a frequency component corresponding to at least one of the frequency components that has passed through the bandpass filter.   The amplification means includes amplification degree adjustment means for adjusting an amplification degree of an electric signal output from at least one of the electric signals output from the plurality of microphones. Or the sound source direction estimation apparatus of 2 description.   The plurality of microphones are embedded in a housing in which an opening for capturing the sound is formed, and the sound that propagates through the opening into the housing is input. The sound source direction estimation apparatus according to any one of claims 1 to 3.

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