JP6500664B2 - Sound field reproduction apparatus, sound field reproduction method, and program - Google Patents

Description

  The present invention relates to a sound field reproduction apparatus, a sound field reproduction method, and a program.

  In the out-of-head localization technology, the sound image is localized outside the head by canceling the characteristics from the headphone to the ear and giving four characteristics from the stereo speaker to the ear. Patent Document 1 discloses a method using Head Related Transfer Function (HRTF) of a listener as a method of localizing a sound image outside the head. In addition, it is known that HRTFs vary greatly among individuals, and in particular, changes in HRTFs due to differences in the shape of the pinna are remarkable.

  Patent Document 2 discloses a method of attaching a microphone to the left and right ears of a listener and recording playback sound from a sound source in order to localize a sound image. Patent Document 2 describes that the sense of direction of the sound source and the factor of the sense of distance are the time difference and the volume difference of the audio signals of the left and right ears. Therefore, in the method described in Patent Document 2, the sound image is localized without performing the convolution process by controlling the time difference and the volume difference when the sound from the sound source enters the left and right ears. Further, paragraph 0008 of Patent Document 2 states that the sound of the actual sound source may be recorded by a monaural microphone.

JP 2002-209300 A Japanese Patent Laid-Open No. 2000-50400

  By the way, with the recent increase in memory capacity and speeding up of calculation speed, it has become possible to perform audio signal processing such as sound image localization using portable terminals such as smart phones and tablets. Therefore, it has become possible to perform measurement calculation of space acoustic transfer characteristics using a microphone terminal attached to a portable terminal.

  In many mobile terminals, the microphone input terminal is not a stereo input but a monaural input. Furthermore, the microphone input terminal may be monaural input even on a personal computer or the like. When measuring the spatial sound transmission characteristics from the speaker to the left and right ears with a portable terminal etc., if the distance from the speaker to the left and right ears is different, the time required for the acoustic signal to reach the left and right ears from the speaker Causes a difference (time difference). In this case, since the microphones installed at the left and right ears can not simultaneously record at the monaural microphone input terminal, it is not possible to acquire the time difference. Therefore, with the monaural microphone input terminal, it is difficult to obtain the space acoustic transfer characteristic reflecting the time difference of the arrival time to the left and right ears.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a sound field reproducing apparatus, a sound field reproducing method, and a program capable of appropriately measuring the transfer characteristic even in the case of monaural microphone input. .

  A sound field reproducing apparatus according to an aspect of the present invention includes a speaker and left and right microphones, and a microphone unit that picks up sound reproduced by the speaker, and a sound pickup signal picked up by the microphone unit is input Monaural input terminal, a first collected signal collected only from the left microphone, a second collected signal collected only from the right microphone, and collected from the left and right microphones. The switch for switching the output of the microphone unit such that the third collected sound signal is input to the monaural input terminal, and the left and right from the speaker based on the first to third collected signals. And a convolution processing unit that convolutes the transfer characteristic into a reproduction signal.

  A sound field reproducing method according to an aspect of the present invention includes a microphone and a microphone unit for collecting a sound reproduced by the speaker, and a microphone and a microphone, the sound collecting signal collected by the microphone unit being input. A sound field reproduction method for reproducing a sound field using a transfer characteristic measured using a monaural input terminal, and the sound is collected only from the left microphone by switching the output from the microphone unit. Measuring the first collected signal, the second collected signal collected only from the right microphone, and the third collected signal collected from the left and right microphones And calculating the transfer characteristics from the speaker to the left and right microphones based on the first to third collected signals, and convolving the transfer characteristics into a reproduction signal. .

  A program according to one aspect of the present invention includes a speaker and left and right microphones, a microphone unit that picks up a sound reproduced by the speaker, and a monaural to which a sound collection signal collected by the microphone unit is input A program that causes a computer to execute a sound field reproduction method of reproducing a sound field using a transfer characteristic measured using an input terminal, the sound field reproduction method switching an output from the microphone unit Thus, the first collected signal collected only from the left microphone, the second collected signal collected only from the right microphone, and the third collected from the left and right microphones. Measuring the respective collected sound signals, calculating the transfer characteristics from the speaker to the left and right microphones based on the first to third collected sound signals, and transmitting A step of convolving the sex playback signal, but with the.

  According to the present invention, it is possible to provide a sound field reproduction apparatus, a sound field reproduction method, and a program capable of appropriately measuring the transfer characteristic even in the case of monaural microphone input.

FIG. 1 is a block diagram showing an out-of-head localization processing apparatus according to the present embodiment. It is a figure which shows the structure for measuring a space sound transfer characteristic. It is a flowchart which shows the out-of-head localization processing method which concerns on this Embodiment. It is a flowchart which shows the time calculation process in the out-of-head localization processing method. It is a wave form diagram for explaining time difference calculation processing. It is a wave form diagram for explaining time difference calculation processing.

An outline of the out-of-head localization process as an example of the sound field reproduction apparatus according to the present embodiment will be described.
The out-of-head localization processing according to the present embodiment performs the out-of-head localization processing using a space acoustic transfer characteristic (also referred to as a space acoustic transfer function) or an ear canal transfer characteristic (also referred to as an ear canal transfer function). In the present embodiment, the localization processing outside the head is realized using the space sound transmission characteristic from the speaker to the listener's ear and the ear canal transmission characteristic in a state of wearing the headphones.

  In the present embodiment, an ear canal transmission characteristic which is a characteristic from the headphone speaker unit to the ear canal entrance in the headphone-mounted state is used. Then, the ear canal transfer characteristic is corrected by performing filter processing using an inverse filter indicating an inverse characteristic of the ear canal transmission characteristic (also referred to as an ear canal correction function). Thereby, the ear canal transmission characteristic can be canceled.

  The out-of-head localization processing apparatus according to the present embodiment is an information processing apparatus such as a personal computer, a smart phone, a tablet PC, etc., processing means such as a processor, storage means such as a memory or hard disk, display means such as a liquid crystal monitor, It has an input unit such as a touch panel, a button, a keyboard, a mouse, and an output unit having headphones or an earphone. As the out-of-head localization processing device, a general-purpose processing device having a monaural input terminal can be used.

  An out-of-head localization processing apparatus 100, which is an example of a sound field reproduction apparatus according to the present embodiment, is shown in FIG. FIG. 1 is a block diagram of the out-of-head localization processing apparatus. The out-of-head localization processing apparatus 100 performs audio signal processing for controlling a sound image on the stereo input signals XL and XR of Lch and Rch, and the user U who wears the headphone 43 the processed signals YL and YR. Output to Therefore, the out-of-head localization processing apparatus 100 performs sound image localization processing on the Lch and Rch stereo input signals XL and XR. Lch and Rch stereo input signals XL and XR are music reproduction signals reproduced from a CD (Compact Disc) player or the like. Note that the out-of-head localization processing apparatus 100 is not limited to a physically single apparatus, and some of the processes may be performed by different apparatuses. For example, part of the processing may be performed by a personal computer or the like, and the remaining processing may be performed by a DSP (Digital Signal Processor) incorporated in the headphone 43 or the like.

  The out-of-head localization processing apparatus 100 includes an out-of-head localization processing unit 10, a filter unit 41, a filter unit 42, and a headphone 43.

  The out-of-head localization processing unit 10 includes convolution calculation units 11, 12, 21, 22 and adders 24, 25. The convolution units 11, 12, 21 and 22 perform convolution processing using space acoustic transfer characteristics. The stereo input signals XL and XR from a CD player or the like are input to the out-of-head localization processing unit 10. In the out-of-head localization processing unit 10, space acoustic transfer characteristics are set. The out-of-head localization processing unit 10 convolutes space acoustic transfer characteristics to the stereo input signals XL and XR of each channel (hereinafter described as ch). The spatial acoustic transfer characteristic may be a head-related transfer function HRTF.

  The space acoustic transfer characteristics have four transfer characteristics Ls, Lo, Ro, and Rs. The four transfer characteristics can be determined using the later-described measuring device shown in FIG. Ls is a transfer characteristic from the speaker 5L to the microphone 2L. Lo is a transfer characteristic from the speaker 5L to the microphone 2R. Ro is a transfer characteristic from the speaker 5R to the microphone 2L. Rs is a transfer characteristic from the speaker 5R to the microphone 2R.

  Then, the convolution unit 11 convolutes the transfer characteristic Ls on the Lch stereo input signal XL. The convolution unit 11 outputs the convolution data to the adder 24. The convolution unit 21 convolves the transfer characteristic Ro with the Rch stereo input signal XR. The convolution operation unit 21 outputs the convolution operation data to the adder 24. The adder 24 adds two convolution calculation data and outputs the sum to the filter unit 41.

  The convolution operation unit 12 convolutes the transfer characteristic Lo with the Lch stereo input signal XL. The convolution unit 12 outputs the convolution data to the adder 25. The convolution unit 22 convolutes the transfer characteristic Rs on the Rch stereo input signal XR. The convolution unit 22 outputs the convolution data to the adder 25. The adder 25 adds the two convolution operation data and outputs the result to the filter unit 42.

  In the filter units 41 and 42, inverse filters according to the ear canal transmission characteristic are set. Then, the inverse filter is convoluted with the reproduction signal subjected to the processing in the out-of-head localization processing unit 10. A filter unit 41 convolves an inverse filter on the Lch signal from the adder 24. Similarly, the filter unit 42 convolves an inverse filter on the Rch signal from the adder 25. The reverse filter cancels the transfer characteristic between the entrance to the ear canal of each user and the headphone speaker unit when the headphones 43 are worn. By doing this, the characteristics of the headphones 43 are corrected. In addition, since a microphone can be installed in an eardrum position when using a dummy head, the reverse filter in this case cancels the transfer characteristic between the eardrum and the headphone speaker unit.

  The filter unit 41 outputs the corrected Lch signal YL to the left unit 43L of the headphone 43. The filter unit 42 outputs the corrected Rch signal YR to the right unit 43R of the headphone 43. The user U wears a headphone 43. The headphone 43 outputs the Lch signal YL and the Rch signal YR to the user U. Thereby, the user U can perceive a sound image localized outside the user U's own head.

  The measuring device which measures space acoustic transfer characteristic is demonstrated using FIG. The measuring device 200 includes a microphone unit 2, a stereo speaker 5, a processing device 6, and a switch 7. The processing device 6 includes a monaural input terminal 8 and a stereo output terminal 9. The switch 7 includes a switch 7a and an adder 7b.

  The processing device 6 is an information processing device such as a personal computer, a smart phone, and a tablet PC. The processing device 6 performs the measurement by executing a program stored in the memory 61 or the like. Specifically, when the processing device 6 executes an application program (application), an impulse signal is generated and measurement of transfer characteristics is started. The processing device 6 may be the same device as the extra-head localization processing device 100 shown in FIG. 1 or may be another device. When the processing device 6 and the out-of-head localization processing device 100 are the same device, the processing device 6 stores the measured transfer characteristic in the memory 61 or the like. When the processing device 6 and the out-of-head localization processing device 100 are separate devices, the processing device 6 transmits a transfer characteristic (transfer function) to the out-of-head localization processing device 100 by wired communication or wireless communication. The signal for measurement is not limited to the impulse signal, and another signal such as a TSP (time-stretched pulse) signal or an M-sequence signal may be used.

  In FIG. 2, the left speaker 5 </ b> L and the right speaker 5 </ b> R are disposed in front of the listener 1. The stereo speaker 5 provided with the left speaker 5 </ b> L and the right speaker 5 </ b> R is connected to the processing device 6 via the stereo output terminal 9. The processing device 6 generates an impulse signal output from each of the left speaker 5L and the right speaker 5R. That is, the measuring apparatus 200 performs measurement of the transfer characteristic Ls from the left speaker 5L to the left microphone 2L and measurement of the transfer characteristic Lo from the right speaker 5R to the right microphone 2R. In FIG. 2, the left speaker 5L is disposed on the front left side of the listener 1 and the right speaker 5R is disposed on the front right side. However, the arrangement of the speakers may be any position, and is not limited to this arrangement. Further, the number of speakers may be one or more than two.

  In addition, a microphone 2L for sound collection is installed at the entrance of the ear canal of the left ear 3L of the listener 1 or at the tympanic membrane position. A microphone 2R for sound collection is installed at the entrance of the ear canal of the right ear 3R of the listener 1 or at the tympanic membrane position. The listener 1 may be a person or a dummy head. Therefore, in the present embodiment, the listener 1 is a concept including not only a person but also a dummy head. The microphone unit 2 having the left microphone 2 </ b> L and the right microphone 2 </ b> R is connected to the switch 7. The switch 7 may be incorporated in the microphone unit 2.

  The switch 7 is connected to a monaural input terminal 8 provided in the processing device 6 via a cable. Accordingly, the left microphone 2L and the right microphone 2R are connected to the monaural input terminal 8 via the switch 7. Furthermore, the microphone unit 2 is connected to the processing device 6 via the monaural input terminal 8. Therefore, the collected sound signal collected by the microphone unit 2 is input to the processing device 6 through the switch 7 and the monaural input terminal 8. The processing device 6 has a memory 61 for storing a sound collection signal, an operation unit 62 for receiving the operation of the listener 1, and a signal amplification unit 63 for amplifying an input signal from the monaural input terminal 8 to an appropriate level. . In place of the signal amplification unit 63, the signal may be amplified by an amplifier (not shown) and then input to the monaural input terminal 8.

  The switch 7 switches the output of the microphone unit 2 so that the sound pickup signal collected by one or both of the left and right microphones 2L and 2R is input to the monaural input terminal 8. The adder 7b adds the signal from the left microphone 2L and the signal from the right microphone 2R. The switch 7a selectively switches the output of only the left microphone 2L, the output of the right microphone 2R, and the output from the adder 7b.

  The connection state is switched by the processing device 6 controlling the switch 7a. A state in which the switch 7a is connected to the left microphone 2L is referred to as a first connection state. A state in which the switch 7a is connected to the right microphone 2R is referred to as a second connection state. A state in which the switch 7a is connected to the adder 7b is referred to as a third connection state. In the first to third connection states, the microphone unit 2 picks up the sounds generated by the speaker unit 5 respectively. Here, a signal collected in the first connection state is referred to as a first collected signal sL. A signal collected in the second connection state is taken as a second collected signal sR. A signal collected in the third connection state is taken as a third collected signal sC.

  A signal collected from only the left microphone 2L is a first collected signal sL. A signal collected from only the right microphone 2R is a second collected signal sR. A signal collected from the left and right microphones 2L and 2R becomes a third collected signal sC. The third sound collection signal sC is a signal in which the first sound collection signal sL and the second sound collection signal sR are superimposed.

  Then, in the first to third connection states, the left speaker 5L reproduces an impulse signal, and the processing device 6 measures the transfer characteristic. That is, the switch 7 switches the output of the microphone unit 2, and the measurement of the transfer characteristic by the impulse signal from the left speaker 5L is performed three times. As a result, the processing device 6 records the first to third collected signals with respect to the impulse signal from the left speaker 5L. The processing device 6 obtains the transfer characteristics Ls and Lo based on the first to third collected sound signals.

  By performing the same measurement on the right speaker 5R, the processing device 6 records the first to third collected signals to the right speaker 5R. The processing device 6 obtains the transfer characteristics Ro and Rs based on the first to third collected sound signals to the right speaker 5R.

  Furthermore, the processing device 6 obtains the time difference d of the time for the sound to reach the left and right ears. Specifically, assuming that the time for the impulse signal to reach from the left speaker 5L to the left microphone 2L is tL and the time for the impulse signal to reach from the right speaker 5R to the right microphone 2R is tR, the time difference is d is obtained by the difference between tL and tR (tL−tR). However, since the collection of the first collected signal sL and the collection of the second collected signal sR are performed separately, the time difference d can be obtained only from the first collected signal sL and the second collected signal sR. It becomes difficult to determine the Therefore, in the processing method according to the present embodiment, the time difference d is determined using the first sound collection signal sL, the second sound collection signal sR, and the third sound collection signal sC.

  This processing method will be described with reference to FIG. FIG. 3 is a flowchart showing a processing method for determining the transfer characteristic. The same processing is applied to each of the left speaker 5L and the right speaker 5R, but here, as a representative, the processing of the left speaker 5L will be described.

  First, when the listener operates the operation unit 62 to start measurement, the Lch signal input to the microphone 2L is measured (S11). Specifically, the processing device 6 causes the left speaker 5L to output an impulse signal as the first connection state by switching the switch 7. Thereby, the first collected sound signal sL is measured. The processing device 6 stores data of the first collected sound signal sL in the memory 61 or the like.

  Next, the Rch signal input to the microphone 2R is measured (S12). Specifically, the processing device 6 causes the left speaker 5L to output an impulse signal as the second connection state by switching the switch 7. Thereby, the second collected sound signal sR is measured. The processing device 6 stores data of the second collected sound signal sR in the memory 61 or the like.

  Further, a signal obtained by adding the Lch signal input to the microphone 2L and the Rch signal input to the microphone 2R is measured (S13). Specifically, the processing device 6 causes the left speaker 5L to output an impulse signal as the third connection state by switching the switch 7. Thereby, the third collected sound signal sC (= sL + sR) is measured. The processing device 6 stores data of the third collected sound signal sC in the memory 61 or the like. The measurement order of the first to third collected sound signals is not particularly limited.

  Then, the processing device 6 calculates the time difference until the sound reaches the left and right microphones 2L and 2R from the left speaker 5L based on the first to third collected sound signals (S14). The method of calculating the time difference will be described with reference to FIGS. 4 to 6. FIG. 4 is a flowchart showing a method of calculating a time difference. FIG. 5 and FIG. 6 are waveform diagrams for explaining the time difference calculation process, and show the first collected signal sL, the second collected signal sR, the addition signal y, and the third collected signal sC, respectively. It is done.

  First, the processing device 6 sets the delay time t to 0 and initializes the delay time of the second collected sound signal sR (S21). FIG. 5 shows the waveform at the delay time t = 0. When the delay time t = 0, the appearance timings of the first collected signal sL and the second collected signal sR coincide with each other. Then, the processing device 6 calculates an addition signal y obtained by adding the first collected sound signal sL [0] and the delayed second collected sound signal sR [t] (S22). Here, the delay time t = 0 is given to the second collected sound signal sR.

  The processing device 6 determines whether the addition signal y matches the third collected signal sC (S23). The processing device 6 generates a difference signal between the addition signal y and the third collected sound signal sC, and compares the representative value of the amplitude value of the difference signal with a predetermined threshold value th. If the representative value of the amplitude value of the difference signal is larger than the predetermined threshold value th, the processing device 6 determines that the addition signal y does not match the third collected sound signal sC (NO in S23). Here, the representative value of the amplitude value of the difference signal may be a value indicating the feature of the difference signal, such as the sum of the amplitude values, the average value, the median value, or the maximum value. The predetermined threshold th to be compared with the representative value may be a predetermined constant, or may be a value calculated as needed based on the amplitude value of the first, second or third collected sound signal. When the processing device 6 determines that the addition signal y does not match the third collected sound signal sC, the processing device 6 adds a predetermined value n to the delay time t (S24). The predetermined value n may be a positive value or a negative value.

  Next, the processing device 6 calculates an addition signal y obtained by adding the first collected sound signal sL [0] and the second collected sound signal sR [t] given the delay time t (S22). . Here, a delay time t = n obtained by adding a predetermined value n to the delay time t = 0 initialized to the second collected sound signal sR is given. Then, the processing device 6 determines again whether or not the addition signal y matches the third collected signal sC (S23). The processing device 6 generates a difference signal between the addition signal y and the third sound collection signal sC, and compares the representative value of the amplitude value of the difference signal with a predetermined threshold th. If the representative value of the amplitude value of the difference signal is smaller than the predetermined threshold value th, the processing device 6 determines that the addition signal y matches the third collected sound signal sC (YES in S23). FIG. 6 shows a waveform when a delay time t = t 'at which the addition signal y matches the third collected signal sC is given. Then, the processing device 6 sets the delay time t when the addition signal y matches the third collected signal sC as the time difference d (S25). By doing this, the time difference d of the arrival time of the sound to the left and right ears can be obtained.

  As described above, the processing device 6 compares the addition signal y with the third collected signal sC. The processing device 6 obtains the time difference d of the arrival time of the sound to the left and right ears based on the comparison result. Specifically, the processing device 6 repeatedly executes the processing of steps S22 to S24 until the addition signal y matches the third collected sound signal sC. That is, the processing device 6 adds the predetermined value n to the delay time t until the addition signal y matches the third collected signal sC, and gradually increases the delay time t. Then, the processing device 6 calculates the time difference d of the arrival times of sounds to the left and right ears from the delay time t given when the addition signal y matches the third collected signal sC. That is, the time difference between the arrival time of the sound from the left speaker 5L to the left microphone 2L and the arrival time of the sound from the left speaker 5L to the right microphone 2R is obtained.

  Then, the processing device 6 obtains the transfer characteristics Ls, Lo reflecting the time difference of the arrival time. By performing the same measurement process, the processing device 6 obtains the transfer characteristics Ro and Rs reflecting the time difference of the arrival time. In the out-of-head localization processing apparatus 100, the convolution processing is performed using the transfer characteristics Ls, Lo, Ro, and Rs in which the time difference is reflected. By doing this, the out-of-head localization processing apparatus 100 can perform appropriate out-of-head localization processing.

  Depending on the arrangement of the speakers, the distances between the speakers and the microphones 2L and 2R may be equal at first glance. However, in practice, the difference in the shape of the head or pinna causes a slight difference in distance, resulting in a time difference. In this case, since it is not clear which signal is delayed, the addition signal y is given both in the case where the first collected signal sL is delayed and in the case where the second collected signal sR is delayed. calculate. Then, it is determined whether or not the addition signal y matches the third collected signal sC. As a result, the delay time t when the third collected signal sC and the addition signal y coincide with each other becomes the time difference d.

  The processing device 6 compares the plurality of addition signals y generated by giving a delay in a predetermined range to the third collected signal sC, respectively, and the addition signal y and the third collected signal sC are most coincident The time difference d may be adopted in the case of

  In the present embodiment, since the switch 7 performs switching, even in the case where only the monaural input terminal 8 is provided, it is possible to acquire the transfer characteristic reflecting the time difference of the arrival time. Therefore, the measuring apparatus 200 can obtain the transfer characteristic that reflects the time difference between the left and right before reaching the both ears important for sound image localization with the monaural input terminal. Since the time difference to reach both ears is individual difference due to the shape of the head and pinnae, the measurement device 200 can obtain a time difference specific to each individual by performing measurement. Therefore, the measuring apparatus 200 can perform the measurement equivalent to a stereo input terminal with a monaural input terminal.

  When the measuring device 200 determines the transfer characteristic reflecting the time difference, the out-of-head localization processing device 100 can localize the sound image at an appropriate position. Moreover, it becomes possible to measure a transfer characteristic using general purpose portable terminals, such as a smart phone and a tablet PC. Furthermore, since the measuring device 200 can use a general-purpose processing device, it is possible to measure the spatial acoustic transmission characteristics according to the actual listener and the listening environment. Therefore, the out-of-head localization processing apparatus 100 can perform appropriate out-of-head localization processing.

  As described above, even when the processing device 6 having no stereo input terminal is used, it is possible to measure the space acoustic transfer characteristic from the speaker to the entrance of the ear canal or the tympanic membrane position (microphone). Therefore, measurement using the general-purpose processing device 6 becomes possible, and the versatility can be improved. The sound field reproduction processing according to the present embodiment is particularly suitable for portable terminals such as smart phones and tablet PCs that do not have stereo input terminals. Furthermore, the processor 6 determines the time difference based only on the actual measured sound collection signal. Even in the case where the generation timing of the impulse signal changes according to the load condition of the processing device 6, accurate measurement can be performed.

  The processing device 6 compares the third collected sound signal sC acquired by measurement and the added signal y calculated by giving a delay in the comparison determination of whether the third collected sound signal sC and the added signal y coincide with each other. A cross-correlation value may be obtained and compared with a predetermined threshold value to determine whether the third collected signal sC and the addition signal y match.

  The processing device 6 calculates the cross-correlation value between the plurality of addition signals y generated by giving a delay in a predetermined range and the third collected signal sC, and adopts the time difference when the correlation value becomes the largest. You may

  In addition, although the switch 7a was provided with the switch 7a which switches connection in said description, the structure of the switch 7 is not restricted to this. The switch 7 may adjust the left-right output balance. For example, the balance adjustment unit sets the state in which the output of the left microphone 2L is 100% and the output of the right microphone 2R is 0% as the first state. The balance adjusting means sets the state in which the output of the left microphone 2L is 0% and the output of the right microphone 2R is 100% in the second state. The balance adjustment means sets the state in which the output of the left microphone 2L is 50% and the output of the right microphone 2R is 50% in the third state.

  In the above description, the space acoustic transfer characteristic is measured using the stereo speaker 5, but the space acoustic transfer characteristic may be measured using only one speaker. In this case, measurement is performed by changing the position of the speaker. That is, after the first to third collected sound signals are detected at the position corresponding to the left speaker 5L, the speaker is moved to the position corresponding to the right speaker 5R. Then, after moving the speaker to the position of the right speaker, the first to third sound collection signals are collected similarly. In this way, measurement with a single speaker is possible. In addition, when using the built-in speaker of portable terminals, such as a smart phone and a tablet PC, a portable terminal is moved and it measures. By doing this, it is possible to measure four transfer characteristics with a simple configuration.

  Although a stereo sound source is used in the present embodiment, a monaural sound source or a sound source of three or more multi-channels may be used. In this case, the speaker positions may be determined by the number of sound sources, and the transfer characteristic reflecting the time difference of the arrival time of the sound from the speakers to the left and right ears may be determined for each speaker position.

  In the above description, the out-of-head localization processing apparatus 100 using the headphones 43 is exemplified as the sound field reproducing apparatus according to the present embodiment, but the sound field reproducing apparatus is not limited to this. The processing method according to the present embodiment can be applied to a sound field reproduction device that reproduces a sound field by convolving transfer characteristics. For example, a sound field reproduction apparatus that performs sound image localization using a stereo speaker, or an out-of-head localization processing apparatus that uses an earphone may be used. That is, in the case of a sound field reproduction apparatus that performs convolution processing using space acoustic transfer characteristics from the speakers to the left and right microphones, the above-described measurement processing can be used.

  Some or all of the above signal processing may be performed by a computer program. The programs described above can be stored and supplied to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include tangible storage media of various types. Examples of non-transitory computer readable media are magnetic recording media (eg flexible disk, magnetic tape, hard disk drive), magneto-optical recording media (eg magneto-optical disk), CD-ROM (Read Only Memory), CD-R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)) are included. Also, the programs may be supplied to the computer by various types of transitory computer readable media. Examples of temporary computer readable media include electrical signals, light signals, and electromagnetic waves. The temporary computer readable medium can provide the program to the computer via a wired communication path such as electric wire and optical fiber, or a wireless communication path.

  As mentioned above, although the invention made by the present inventor was concretely explained based on an embodiment, the present invention is not limited to the above-mentioned embodiment, and can be variously changed in the range which does not deviate from the gist. Needless to say.

1 listener 2 microphone unit 2L left microphone 2R right microphone 3L left ear 3R right ear 5 stereo speaker 5L left speaker 5R right speaker 6 processor 7 switch 7a switch 7b adder 8 monaural input terminal 9 stereo output terminal 10 head outside location Processing unit 11 Convolution operation unit 12 Convolution operation unit 21 Convolution operation unit 22 Convolution operation unit 24 Adder 25 Adder 41 Filter unit 43 Filter unit 43 Headphone 43L Headphone left unit 43R Headphone right unit 61 Memory 62 Operation unit 63 Signal amplification Part 100 Out-of-head localization processor 200 Measurement device

Claims (5)

A speaker,
A microphone unit provided with left and right microphones and collecting the sound reproduced by the speaker;
A monaural input terminal to which a sound collection signal collected by the microphone unit is input;
The first collected signal collected only from the left microphone, the second collected signal collected only from the right microphone, and the third collected signal collected from the left and right microphones A switch for switching the output of the microphone unit so that each is input to the monaural input terminal;
A processing unit that calculates transfer characteristics from the speaker to the left and right microphones based on the first to third collected signals,
And a convolution processing unit that convolutes the transfer characteristic into the reproduction signal.   The processing unit calculates a time difference in arrival time of sound from the speaker to the left and right microphones based on the first to third collected signals, and is based on the first and second collected signals. The sound field reproducing apparatus according to claim 1, wherein the transfer characteristic reflecting the time difference is calculated. The processing unit is
An addition signal is generated by delaying either one of the first collected signal or the second collected signal and adding it to the other signal, and the added signal and the third collected signal are The sound field reproduction device according to claim 2, wherein it is determined whether or not they coincide, and the time difference is calculated based on a delay in the case of coincidence. A speaker,
A microphone unit provided with left and right microphones and collecting the sound reproduced by the speaker;
A sound field reproduction method for reproducing a sound field using a transfer characteristic measured using a monaural input terminal to which a sound collection signal collected by the microphone unit is input,
By switching the output from the microphone unit, the first collected signal collected only from the left microphone, the second collected signal collected only from the right microphone, and the left and right Measuring each of a third collected signal collected from the microphone;
Calculating transfer characteristics from the speaker to the left and right microphones based on the first to third collected signals,
And c. Convoluting the transfer characteristic into a reproduction signal. A speaker,
A microphone unit provided with left and right microphones and collecting the sound reproduced by the speaker;
The program is a program that causes a computer to execute a sound field reproduction method of reproducing a sound field using a transfer characteristic measured using a monaural input terminal to which a sound collection signal collected by the microphone unit is input. ,
The sound field reproduction method is
By switching the output from the microphone unit, the first collected signal collected only from the left microphone, the second collected signal collected only from the right microphone, and the left and right Measuring each of a third collected signal collected from the microphone;
Calculating transfer characteristics from the speaker to the left and right microphones based on the first to third collected signals,
Consolidating the transfer characteristic into a reproduction signal.

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