JP4929711B2 - Sound emission and collection device - Google Patents

Description

  The present invention relates to a sound emission and collection device that is integrally provided with a speaker and a microphone, and more particularly, to a sound emission and collection device that suppresses the sound that circulates from a speaker to a microphone while having a compact configuration.

  As an audio communication system for conducting an audio conference (communication conference) in a remote place, an audio conference apparatus that is integrally provided with a speaker and a microphone is widely used. The audio conference apparatus transmits a collected signal collected by the microphone to the connection destination and emits an audio signal received from the connection destination from the speaker. When a conference is held among a plurality of people, such an audio conference apparatus is often installed at the center of a conference participant (the center of a conference desk or the like). Therefore, it is desired that such an audio conference apparatus be miniaturized. For example, as shown in Patent Document 1, a miniaturized audio conference apparatus that omits a speaker box has been proposed.

In addition, since the audio conference apparatus includes a speaker and a microphone in the same space, when the audio signal received from the connection destination is emitted from the speaker, the audio is collected as an echo by the microphone and includes this echo. The collected sound signal is transmitted to the connection destination. Therefore, as shown in Patent Document 2, an audio conference apparatus having an echo canceller function has been proposed in which a microphone is accommodated at the tip of a cylindrical elastic body and acoustic coupling between a speaker and a microphone is suppressed. ing.
JP-A-8-204803 JP-A-8-298696

  However, although the configuration of Patent Document 1 is a compact configuration, the speaker and the microphone are close to each other, and the wraparound volume from the speaker to the microphone is increased. On the other hand, in the configuration of Patent Document 2, the wraparound sound is suppressed by the echo canceller function, and further, the acoustic coupling inside the housing is suppressed by the elastic body. Therefore, the speaker and the microphone are close to each other. For this reason, there is still a problem that the sound emitted from the speaker easily goes around the microphone, and a large processing load is imposed on the echo canceller function.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sound emitting and collecting apparatus that has a compact configuration and suppresses sound that circulates from a speaker to a microphone and improves an S / N ratio.

The sound emission and collection device of the present invention is a casing having two opposing surfaces, and is arranged circumferentially on the first surface side of the casing, and directs a directivity axis in the center direction of the circle, and A plurality of unidirectional microphones installed point-symmetrically with respect to the center of the circle, and a sound emitting surface parallel to a second surface facing the first surface of the housing, A speaker that emits sound from the second surface to the outside of the housing, the center of the sound emitting surface and the center of the circle being on the same vertical line with respect to the first surface and the second surface, and the adjacent unidirectional microphone Signal processing means for adding the collected sound signals, and the signal processing means performs addition processing for each of the plurality of unidirectional microphones, and determines the sound source direction based on the signal strength of the added sound collection signals. It is characterized by detecting .

  In this configuration, the sound emitted from the speaker installed on the second surface side serving as the sound emitting surface is reflected on the top surface of the desk on which the sound emitting and collecting device is installed and is reflected on the side surface side of the housing. Propagated. At this time, the sound intensity propagated to each part of the side surface is substantially equal. Then, a part of the sound emitted from the speaker goes through the side surface to the first surface side where a plurality of unidirectional microphones are installed.

  Each of the plurality of unidirectional microphones is arranged circumferentially on the first surface side. At this time, the center of the circle and the center of the sound emitting surface are on the same vertical line with respect to the first surface and the second surface, and the center direction of the circle is the direction of the directivity, that is, the sound collection sensitivity is high. It is installed in the direction.

  For this reason, the sound that wraps around the first surface is not a unidirectional microphone arranged at the closest position to the side surface position where the sound wraps around, but is opposite to the side surface position where the sound wraps around. The sound is collected mainly by a unidirectional microphone arranged at the farthest position. As a result, the propagation path (echo path) of the wraparound sound becomes long, and a large attenuation of the wraparound sound is obtained before the sound is picked up by the unidirectional microphone.

  In this configuration, since the arrangement positions of the plurality of unidirectional microphones are point-symmetric, the wraparound sound to each unidirectional microphone is substantially the same.

  Further, the sound emission and collection device of the present invention is a unidirectionally arranged in a point-symmetrical position with respect to each unidirectional microphone and the center of the circle from the sound collected signals of the unidirectional microphones arranged symmetrically. And a difference calculation means for generating a difference-corrected sound pickup signal by calculating a difference of the sound pickup signal with the directional microphone.

  In this configuration, as described above, the sneak sound collected by each unidirectional microphone is hardly changed, and the sneak sound is substantially equivalent between unidirectional microphones arranged in point symmetry, in particular. By subtracting the sound pickup signals of these unidirectional microphones, a differential corrected sound pickup signal from which the signal component due to the wraparound sound is removed can be obtained.

  According to this invention, a plurality of unidirectional microphones are circumferentially arranged on one surface of the casing, set with high sensitivity directivity in the center direction of the circle, and the speaker is mounted on the casing. By disposing on the other surface, the propagation distance of the wraparound sound from the speaker to the microphone can be effectively earned. Thereby, although it is a compact structure, the audio | voice which wraps around from a speaker to a microphone can be suppressed and S / N ratio can be improved.

A sound emitting and collecting apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a main part of a sound emission and collection device 100 according to the present embodiment, in which (A) is a plan view and (B) is a cross-sectional view taken along line AA ′ in (A). In FIGS. 1A and 1B, the right side toward the paper surface is the + X direction, and the left side toward the paper surface is the −X direction. In FIG. 1A, the upper side toward the paper surface is the + Y direction, and the lower side toward the paper surface is the -Y direction. In FIG. 1B, the upper side toward the paper surface is the + Z direction, and the lower side toward the paper surface is the -Z direction.

  The sound emission and collection device 100 of the present embodiment includes a housing 1, a plurality of microphones 2A to 2H, a speaker 3, and a signal processing function unit shown in FIG.

  The casing 1 has a substantially cylindrical outer shape, and has a first surface 10A and a second surface 10B that are substantially the same size and are flat, and are connected at the edges of the first surface 10A and the second surface 10B. And, it has a circumferential side surface 10C in which these are arranged at predetermined intervals. In the vicinity of the edge portion of the second surface 10B, four foot portions 4 are disposed, each of which is disposed at an interval of approximately 90 degrees.

  A concave portion 11 having a circular planar shape is formed on the first surface 10A of the housing 1, and a circular center when the first planar surface 10A is viewed in plan and a circular center when the concave portion 11 is viewed in plan match. To do. This center point is hereinafter referred to as “center point O”.

  The microphones 2 </ b> A to 2 </ b> H are unidirectional microphones and are arranged at point-symmetric positions with the center point O as a reference point. Further, each of the microphones 2A to 2H is installed at a predetermined distance or more from the center point O, and more preferably installed at a position near the edge portion of the first plane 10A.

  Specifically, as shown in FIG. 1A, the microphones 2A to 2H are respectively set along the inner wall surface 12 that is the same distance from the center point O and the microphone 2A is + X with the center point O as a reference point. The microphone 2E is arranged in the −X direction. Similarly, with the center point O as a reference point, the microphone 2B is arranged in a 45 degree direction in the + X direction and the + Y direction, and the microphone 2F is arranged in a 45 degree direction in the −X direction and the −Y direction. With the center point O as a reference point, the microphone 2C is arranged in the + Y direction, and the microphone 2G is arranged in the -Y direction. Further, with the center point O as a reference point, the microphone 2D is arranged in a 45 degree direction in the −X direction and the + Y direction, and the microphone 2H is arranged in a 45 degree direction in the + X direction and the −Y direction.

  Each of the microphones 2 </ b> A to 2 </ b> H is installed such that the direction of directivity is the direction toward the center point O. Thereby, each microphone is set such that the sound collection sensitivity in the direction of the center point O is higher than the sound collection sensitivity in the other direction.

  The second surface 10B of the housing 1 has a relationship in which the second surface 10B and the sound emitting surface substantially coincide with each other, and the sound emitting direction is from the second surface 10B to the external direction of the housing 1. A speaker 3 is arranged. The speaker 3 is an omnidirectional speaker including a cone type speaker unit, a horn type speaker unit, and the like, and the center of the sound emitting surface of the speaker 3 passes through the center point O of the first plane 10A and is perpendicular to the first surface 10A. It is arranged to be located in.

  Further, although not shown in FIG. 1, a signal processing function unit described later is installed in an empty space other than the arrangement positions of the microphones 2 </ b> A to 2 </ b> H and the speaker 3 in the housing 1. The input / output connector 26 is installed, for example, on the side surface 10C of the housing 1.

  Such a sound emitting and collecting apparatus 100 is arranged and used as shown in FIG.

  FIG. 2 is a diagram illustrating a case where two users 201 and 202 use the sound emitting and collecting apparatus 100 of the present embodiment, where (A) is a plan view and (B) is a side view. 2A and 2B, the right side toward the paper surface is the + X direction, and the left side toward the paper surface is the -X direction. In FIG. 2A, the upper side toward the paper surface is the + Y direction, and the lower side toward the paper surface is the -Y direction. In FIG. 2B, the upper side toward the paper surface is the + Z direction, and the lower side toward the paper surface is the -Z direction.

  The sound emission and collection device 100 is disposed on the top surface at a substantially central position of the top surface of the desk 200. At this time, the plurality of feet 4 are brought into contact with the top surface of the desk, so that the housing 1 is arranged at a predetermined distance from the top surface.

  Although not shown, the sound emitting and collecting apparatus 100 is connected to the LAN via the input / output connector 26 described above, and is separated from a remote location, for example, a completely different place from the room where the apparatus is installed. , Connected to another sound emitting and collecting device arranged in.

  Users 201 and 202 face each other on opposite sides of the desk 200 on which the sound emitting and collecting apparatus 100 is disposed. In the example of FIG. 2, the user 201 is in the −X direction with respect to the sound emitting and collecting apparatus 100, and the user 202 is in the + X direction with respect to the sound emitting and collecting apparatus 100.

(1) Voices from the users 201 and 202 These users 201 and 202 speak to the sound emitting and collecting apparatus 100 when talking to the other user in the room of another sound emitting and collecting apparatus.

  When the user 201 utters, the uttered sound 301 reaches the microphones 2A to 2H of the sound emitting and collecting apparatus 100 while diffusing and attenuating. Here, as described above, the microphone 2A has a directivity having high sound collection sensitivity in the direction of the center point O of the housing 1, that is, in the −X direction where the user 201 exists, with respect to the microphone 2A. . Therefore, the microphone 2A is present at a position farthest from the user 201 as compared with the other microphones 2B to 2H, but can utter the uttered sound 301 with high sensitivity. On the other hand, the microphone 2E that is point-symmetric with the microphone 2A is present at a position closest to the user 201 as compared to the other microphones 2A to 2D and 2F to 2H. However, since the microphone 2E has high sound collection sensitivity in the + X direction and directivity having almost no sound collection sensitivity is set in the -X direction, the utterance sound 301 is hardly collected.

  When the user 202 utters, the uttered sound 302 reaches the microphones 2 </ b> A to 2 </ b> H of the sound emitting and collecting apparatus 100 while being diffused and attenuated. Here, as described above, the microphone 2E is set to have directivity having high sound collection sensitivity in the direction of the center point O of the housing 1, that is, in the + X direction where the user 202 exists, with respect to the microphone 2E. Therefore, the microphone 2E is present at a position farthest from the user 202 as compared with the other microphones 2A to 2D and 2F to 2H, but can utter the uttered sound 302 with high sensitivity. On the other hand, the microphone 2A that is point-symmetric with the microphone 2E is located closest to the user 202 as compared to the other microphones 2B to 2H. However, since the microphone 2A has high sound collection sensitivity in the −X direction and directivity having almost no sound collection sensitivity is set in the + X direction, the microphone 2A hardly collects the uttered sound 302.

  Thus, the user's uttered sound is mainly collected by the microphone disposed at the opposite position extending from the side surface where the user is located through the center point O.

  By the way, although the invention of the above-mentioned patent document 2 is a sound emission and collection device in which a speaker is arranged on the upper surface and a microphone is arranged on the side surface, as shown in FIGS. It is also conceivable to arrange 93 on the lower surface. In this case, the microphone 92A disposed on the side surface of the casing 91 is set so that directivity is directed toward the outside of the side surface of the casing 91, and the sound generated by the user 201 closest to the microphone 92A is collected. . In the following description, the sound emitting and collecting apparatus having the configuration shown in FIGS. 3B and 3D is a representative example of a conventional sound emitting and collecting apparatus as a comparison target of the present embodiment.

  FIG. 3A is a conceptual diagram showing the transmission distance Lv1 of the uttered sound with respect to the microphone that performs the main sound collection in the sound emitting and collecting apparatus 100 of the present embodiment, and FIG. It is a conceptual diagram showing transmission distance Lv0 of the utterance sound with respect to the microphone which performs main sound collection in the sound emission and collection apparatus which has arrange | positioned the microphone. FIGS. 3A and 3B show a case where sounds generated by the user 201 are collected by the microphone 2A and the microphone 92A, respectively.

  The sound transmission distance Lv1 in the sound emission and collection device of the present embodiment shown in FIG. 3A is longer than the sound transmission distance Lv0 in the conventional sound emission and collection device shown in FIG. 3B. . However, compared to the distance from the user 201 to the sound emission and collection device (corresponding to the distance from the user 201 to the microphone 92A), the difference in the distance from the side surface on the user 201 side to the microphone 2A is extremely short, and the utterance sound by this The increase in the amount of attenuation is almost unnecessary to consider. Therefore, the sound emitting and collecting apparatus according to the present embodiment can collect the uttered sound with the sensitivity, that is, the sound pressure level, which is substantially the same as the conventional one.

(2) Audio from a partner in another room When these users 201 and 202 listen to a voice from a partner user in a room of another sound emitting and collecting device, they listen to the output sound from the speaker 3 of the sound emitting and collecting device 100. It becomes.

  The speaker 3 is disposed on the second surface 10B (lower surface) of the housing 1, that is, the surface facing the top surface of the desk 200, and emits sound from the other user. The emitted sound 300 is reflected on the top surface of the desk 200 and propagates while being diffused in a circumferential direction in the horizontal direction, and is diffused from the region of the second surface 10B including the upward direction. , And is uniformly propagated to the space including the users 201 and 202. At this time, a part of the sound 300 is propagated to the first surface 10 </ b> A side of the housing 1 through the side surface 10 </ b> C of the housing 1. This sound is hereinafter referred to as wraparound sound.

  Here, as in the case of the uttered sound described above, each of the microphones 2A to 2H collects the wraparound sound propagated from the end in the direction extending through the center point O, that is, the side surface 10C at the farthest position, The wraparound sound propagated from the side surface 10C at the position closest to each of the microphones 2A to 2H is hardly collected. That is, the wraparound sound with the longest propagation path is collected.

  FIG. 3C is a conceptual diagram showing the transmission distance Ls1 of the wraparound sound with respect to the microphone in the sound emitting and collecting apparatus 100 of the present embodiment, and FIG. 3D has the same configuration as FIG. It is a conceptual diagram showing the transmission distance Ls0 of the wraparound sound with respect to the microphone in the conventional sound emission and collection apparatus.

  The wraparound sound transmission distance Ls1 of the present embodiment shown in FIG. 3C is longer than the conventional wraparound sound transmission distance Ls0 shown in FIG. This is because the conventional transmission distance Ls0 substantially coincides with the length from the speaker 93 to the side surface 10C on which the microphone 92A having the directivity direction on the outside of the housing 91 is installed. On the other hand, the transmission distance Ls1 of the present embodiment is approximately the length from the speaker 3 to the side surface 10C, the height of the side surface 10C, and the length from the position of the side surface 10C to the microphone 2A farthest disposed at this position. Matches the total distance. Thereby, the transmission distance Ls1 of the wraparound sound according to the present embodiment is at least twice as long as the conventional transmission distance Ls0. As a result, the sound emitting and collecting apparatus according to the present embodiment can significantly attenuate the wraparound sound that is collected compared to the conventional sound emitting and collecting apparatus.

  Further, conventionally, only the 90-degree propagation direction changes from the second surface 10B to the side surface 10C, but in the configuration of the present embodiment, the 90-degree propagation direction further changes from the side surface 10C to the first surface 10A. In other words, in this embodiment, the 90-degree change in the propagation direction is one time more than in the past. Here, such a change in the propagation direction of the wraparound sound has a reflection wall or the like ahead of the propagation direction, and is not forcedly changed by reflection by the wall surface, but is naturally wraparound. Depending on, a significant attenuation is obtained. Therefore, the sound emission and collection device of the present embodiment can attenuate the wraparound sound very significantly compared to the conventional sound emission and collection device.

  As described above, by using the configuration of the present embodiment, it is possible to collect a voice utterance from the user, which is a necessary voice, with high sensitivity and greatly reduce the voice that wraps around from the speaker to the microphone while keeping the housing small. Can be attenuated. Thereby, a high S / N ratio can be realized.

  Next, a signal processing function unit that processes the collected sound signal collected as described above will be described.

FIG. 4 is a block diagram showing the configuration of the sound emission and collection device of the present embodiment.
The sound emission and collection device of the present embodiment includes the input / output connector 26 in addition to the microphones 2A to 2H and the speaker 3 described above, and further includes input amplifiers 21A to 21H and an A / D converter as signal processing function units. 22A to 22H, a microphone signal processing circuit 23, an echo canceller 24, an input / output interface 25, a D / A converter 31, and an output amplifier 32.

  The input / output interface 25 gives the input audio signal input from the input / output connector 26 to the D / A converter 31 via the echo canceller 24. The D / A converter 31 converts the input audio signal into an analog signal and supplies it to the output amplifier 32, and the output amplifier 32 amplifies the input audio signal and outputs it to the speaker 3. The speaker 3 converts the input sound signal into sound and emits the sound.

  Each of the microphones 2A to 2H collects sound from the outside, converts it into a sound collection signal, and outputs it to the input amplifiers 21A to 21H. Each of the input amplifiers 21A to 21H amplifies the collected sound signal and outputs it to the A / D converters 22A to 22H. The A / D converters 22 </ b> A to 22 </ b> H digitally convert each collected sound signal and output it to the microphone signal processing circuit 23. Hereinafter, the collected sound signals collected by the microphones 2A to 2H and output from the A / D converters 22A to 22H are simply referred to as signals A to H, respectively.

FIG. 5 is a detailed block diagram of the microphone signal processing circuit 23.
The microphone signal processing circuit 23 includes adders (subtractors) 231A to 231H, a select / mixing circuit 232, and a maximum signal strength detection circuit 233.

The adder 231A receives the signal A output from the A / D converter 22A and the signal E output from the A / D converter 22E. The adder 231A subtracts the signal E from the signal A and outputs a correction signal A. Here, the signal A is a sound collected signal by the microphone 2A, and the signal E is a sound collected signal by the microphone E. As described above, since the microphone 2A and the microphone 2E are arranged at point-symmetric positions with respect to the center point O, the wraparound sound collected by each is substantially the same. Thus, by subtracting the signal E from the signal A, this wraparound audio component can be reduced.

  Similarly, the correction signal B is generated by subtracting the signal F from the signal B by the adder 231B, the correction signal C is generated by subtracting the signal G from the signal C by the adder 231C, and the correction signal D is added. The signal 231D is generated by subtracting the signal H from the signal D.

  The adder 231E receives the signal E output from the A / D converter 22E and the signal A output from the A / D converter 22A. The adder 231E subtracts the signal A from the signal E and outputs a correction signal E. Similarly, the correction signal F is generated by subtracting the signal B from the signal F by the adder 231F, the correction signal G is generated by subtracting the signal C from the signal G by the adder 231G, and the correction signal H is added. The signal 231H is generated by subtracting the signal D from the signal H.

  As a result, the correction signal A to the correction signal H can each reduce the wraparound sound component.

  The generated correction signals A to H are input to the select / mixing circuit 232 and the maximum signal strength detection circuit 233. The maximum signal strength detection circuit 233 compares the signal strengths of the correction signals A to H, that is, the sound pressure level, selects the correction signal with the highest signal strength, and selects the correction signal with the highest signal strength. Is supplied to the select / mixing circuit 232. The select / mixing circuit 232 selects a corresponding correction signal from the input correction signals A to H based on the selection information given from the maximum signal intensity detection circuit 233 and outputs the selected correction signal to the echo canceller 24. The maximum signal strength detection circuit 233 detects the correction signal with the highest signal strength, selects the correction signal with the maximum signal strength and a plurality of correction signals adjacent to the correction signal, and selects / mixes the selection signal. 232 may be given. Furthermore, in view of the case where there are a plurality of sound sources in different directions, a plurality of correction signals may be selected in order from the correction signal with the highest signal intensity and provided to the select / mixing circuit 232. In these cases, the select / mixing circuit 232 selects a plurality of corresponding correction signals based on the selection information, mixes them, and outputs them to the echo canceller 24.

  By performing such a selection process, a correction signal having a low signal strength, which is unlikely to be a voice uttered by the user, is deleted, so that the S / N can be further improved.

FIG. 6 is a detailed block diagram of the echo canceller 24.
The echo canceller 24 includes an adaptive filter 241 and an adder 242. The adaptive filter 241 includes a digital filter such as an FIR filter, estimates the transfer function of the acoustic propagation path from the speaker 3 to the microphones 2A to 2H, and filters the filter coefficient of the FIR filter so as to simulate the estimated transfer function Is calculated. The adaptive filter 241 generates a pseudo regression sound signal using the estimated filter coefficient and outputs the pseudo regression sound signal to the adder 242. The adder 242 subtracts the pseudo regression sound signal from the output signal of the microphone signal processing circuit 23 and outputs the result to the input / output interface 25 as an output audio signal. Here, the estimation of the transfer function and the calculation of the filter coefficient are performed based on the input audio signal supplied to the speaker 3 by feeding back the residual signal, which is the signal output from the adder 242, as a reference signal to the adaptive filter 241. Iteratively using an adaptive algorithm. Thereby, the estimation of the transfer function and the setting of the filter coefficient are optimized.

  By performing such processing, the wraparound audio component is further suppressed, and the S / N ratio of the audio signal output to the input / output interface 25 is further improved.

  As described above, in the sound emission and collection device of the present embodiment, the wraparound sound can be mechanically reduced by making the positional relationship between the speaker and the microphone as described above. In addition, by setting the microphone installation pattern as described above, it is possible to effectively suppress the sneak sound component included in the collected sound signal of each microphone, and further, by performing echo canceling, the sneak sound component Can be further suppressed. Thereby, a very excellent S / N ratio can be realized for the output audio signal.

  In the present embodiment, the concave portion 11 of the first surface 10A of the housing 1 is formed, and the microphones 2A to 2H are arranged on the inner peripheral surface 12 of the concave portion 11, but as shown in FIG. The microphones 2A to 2H may be arranged in a structure.

  7A and 7B are diagrams showing the configuration of the main part of the sound emitting and collecting apparatus of the present embodiment of the sound emitting and collecting apparatus of another configuration of the present embodiment, where FIG. 7A is a plan view and FIG. It is AA 'sectional drawing in. In the sound emission and collection device shown in FIG. 7, the microphones 2A to 2H are arranged on the first surface 10A, and these microphones 2A to 2H are covered with a mesh-like cover 13, and the other configurations are the same. Even with such a configuration, the above-described effects can be achieved.

  Further, in the present embodiment, the short cylindrical housing 1 has been described as an example, but may be an elliptic cylinder shape with a planar cross section being an ellipse, and may be a rectangular parallelepiped shape.

  In the present embodiment, the second surface 10B side having the speaker 3 is disposed so as to face the top surface of the desk 200. However, the second surface 10B side having the speaker 3 is arranged in the room where the user is present. You may arrange | position so that the leg part 4 may be connected to a ceiling surface toward a ceiling.

  Further, in this embodiment, the case where there are eight microphones and one speaker is shown. However, as described above, the microphone and the speaker are arranged on the opposite surfaces of the housing, and the microphone directivity as described above. Is set, the number of microphones and the number of speakers can be set as appropriate.

Further, the configuration of the microphone signal processing circuit 23 is not limited to the above example.
FIG. 8 is a block diagram showing another configuration of the microphone signal processing circuit 23. The microphone signal processing circuit 23 shown in FIG. 8 differs from the microphone signal processing circuit 23 shown in FIG. 5 only in the signal synthesis portion.
The adder 231A receives the signal A output from the A / D converter 22A and the signal B output from the A / D converter 22B. The adder 231A adds the signal A and the signal B and outputs the result. Similarly, the adder 231B adds and outputs the signal B and the signal C, the adder 231C adds and outputs the signal C and the signal D, and the adder 231D adds the signal D and the signal E. Output. The adder 231E adds and outputs the signal E and the signal F, the adder 231F adds and outputs the signal F and the signal G, and the adder 231G adds the signal G and the signal H. The adder 231H adds the signal H and the signal A and outputs the result. As described above, the microphone signal processing circuit 23 shown in FIG. 8 adds and outputs the collected sound signals obtained from two adjacent microphones. In this way, by adding the collected sound signals of adjacent microphones, the collected sound signal component from the front direction of the microphone, that is, the direction in which high sound collection sensitivity is set, is strengthened, and the collected sound signal from other directions Ingredients are weakened. Thereby, a signal with higher directivity can be obtained.

Further, the configuration of the microphone signal processing circuit 23 may be as follows.
FIG. 9 is a block diagram of a signal synthesizer in another microphone signal processing circuit 23.
The microphone signal processing circuit 23 shown in FIG. 9 is also different from the microphone signal processing circuit 23 shown in FIG.
The microphone signal processing circuit 23 shown in FIG. 9 includes adders 237A to 237H, delay circuits 234A to 234H, 235A to 235H, and 236A to 236H. Signals A to H are input to delay circuits 234A to 234H, 235A to 235H, and 236A to 236H, respectively. For example, the signal A is input to the delay circuits 234A, 235A, and 236A, and the other signals B to H are similarly processed.

  Each of the delay circuits 234A to 234H, 235A to 235H, 236A to 236H delays the input signals so that the three signals input to the adders 237A to 237H are in phase.

  The adder 237A adds the output signal (signal A) of the delay 234A, the output signal (signal B) of the delay 235B, and the output signal (signal C) of the delay 236C, and outputs the result. Similarly, the adder 237B adds and outputs the delayed signals B, C, and D, and the adder 237C adds the delayed signals C, D, and E, respectively. The adder 237D adds the signal D, the signal E, and the signal F that have been subjected to the delay processing, and outputs the result. Further, the adder 237E adds and outputs the delayed signals E, F, and G, and the adder 237F adds the delayed signals F, G, and H to the output. The adder 237G adds and outputs the delayed signals G, H, and A, and the adder 237H adds the delayed signals H, A, and B, respectively, and outputs the result. To do. As a result, the collected sound signals from the three adjacent microphones are added in phase. As a result, the signal intensity in the specific direction is further increased, the S / N is improved, and the directivity in the specific direction is further increased. The number of signals to be added is not limited to three, and the S / N ratio in a specific direction can be improved by adding or subtracting more signals.

  The microphone signal processing circuit 23 shown in FIGS. 8 and 9 is configured to directly process the output signals A to H of the A / D converters 22A to 22H. However, the microphone signal processing circuit 23 is generated using the circuit shown in FIG. The corrected signals A to H may be input. Thereby, the S / N ratio is further improved.

It is a figure which shows the structure of the principal part of the sound emission and collection apparatus of embodiment of this invention. It is the figure which showed the case where the two users 201 and 202 use the sound emission and collection apparatus 100 of embodiment of this invention. It is a conceptual diagram showing the transmission distance Lv1 of the utterance sound with respect to the microphone which mainly collects sound in the sound emission and collection apparatus 100 of embodiment of this invention, and the utterance sound with respect to the microphone which mainly collects sound in the conventional sound emission and collection apparatus Is a conceptual diagram showing the transmission distance Lv0 of the microphone, and is a conceptual diagram showing the transmission distance Ls1 of the wraparound sound with respect to the microphone, and the transmission distance Ls0 of the wraparound sound with respect to the microphone in the conventional sound emitting and collecting apparatus in which the speaker is arranged on the side surface of the housing. It is a conceptual diagram showing. It is a block diagram which shows the structure of the sound emission and collection apparatus of embodiment of this invention. 3 is a detailed block diagram of a microphone signal processing circuit 23. FIG. This is a detailed block of the echo canceller 24. It is a figure which shows the structure of the principal part of the sound emission and collection apparatus of this embodiment of the sound emission and collection apparatus of the other structure of this embodiment. 6 is a block diagram showing another configuration of the microphone signal processing circuit 23. FIG. 7 is a block diagram of a signal synthesis unit in another microphone signal processing circuit 23. FIG.

Explanation of symbols

100-Sound emitting and collecting device, 200-Desk, 201, 202-User, 300-Sound emitted, 301, 302-Speech sound,
1, 91-housing, 10A-first surface of housing 1, 10B-second surface of housing 1, 10C-side surface of housing 1, 2A-2H, 92A-microphone, 3-speaker, 4-foot Part,
21A-21H-input amplifier, 22A-22H-A / D converter, 23-microphone signal processing circuit, 231A-231H, 237A-237H-adder, 232-select / mixing circuit, 233-maximum signal strength detection circuit, 234A 234H, 235A to 235H, 236A to 236H-delay circuit, 24-echo canceller, 241-adaptive filter, 242-adder, 25-input / output interface, 26-input / output connector, 31-D / A converter, 32 −Output amplifier

Claims (2)

A housing having two opposing surfaces;
A plurality of unidirectional elements arranged circumferentially on the first surface side of the housing, each directed with a directivity axis in the center direction of the circle, and symmetric with respect to the center of the circle Microphone
A sound emitting surface parallel to a second surface facing the first surface of the housing; and the center of the sound emitting surface and the center of the circle are on the same vertical line with respect to the first surface and the second surface A speaker that emits sound from the second surface to the outside of the housing;
An addition process is performed in which the sound pickup signal of one unidirectional microphone is added to the sound pickup signal of another unidirectional microphone adjacent to the one unidirectional microphone along the circumference. Signal processing means;
With
The signal processing means includes
A sound emitting and collecting apparatus, wherein the addition processing is performed for each of the plurality of unidirectional microphones, and a sound source direction is detected based on the signal intensity of the added sound collection signals. The sound pickup signal between each unidirectional microphone and the unidirectional microphone arranged at a point-symmetrical position with respect to the center of the circle is subtracted from the sound collection signal of each unidirectional microphone arranged symmetrically with respect to the point. The sound emission and collection device according to claim 1 , further comprising difference calculation means for calculating and generating a difference corrected sound collection signal.

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