WO2005125273A1 - ハウリング検出装置およびその方法 - Google Patents
ハウリング検出装置およびその方法 Download PDFInfo
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- WO2005125273A1 WO2005125273A1 PCT/JP2005/010959 JP2005010959W WO2005125273A1 WO 2005125273 A1 WO2005125273 A1 WO 2005125273A1 JP 2005010959 W JP2005010959 W JP 2005010959W WO 2005125273 A1 WO2005125273 A1 WO 2005125273A1
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- howling
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/02—Circuits for transducers, loudspeakers or microphones for preventing acoustic reaction, i.e. acoustic oscillatory feedback
Definitions
- the present invention relates to a howling detection device and a method thereof, and more particularly, to a howling system that mixes a plurality of audio signals and loudspeaks to generate howling for each of the plurality of audio signals.
- TECHNICAL FIELD The present invention relates to a howling detection device and a method for detecting a degree of danger to be caused.
- a howling suppression device that detects the occurrence of howling and suppresses the howling has been developed.
- a knocking suppression device using an applied filter, a notch filter, or the like is known (for example, see Patent Documents 1 and 2).
- FIG. 10 is a diagram showing a configuration example in which a howling suppression device disclosed in Patent Document 1 and Patent Document 2 is adopted in a loudspeaker system 9 that mixes a plurality of audio signals to loudspeak.
- FIG. 10 shows a configuration example in which howling that occurs when a speaker and a plurality of microphones are in the same sound field is suppressed.
- two audio signals are input from two microphones as a plurality of audio signals.
- the loudspeaker system 9 includes a first microphone 91a, a second microphone 9 lb, a sound characteristic adjustment unit 92, a sound mixing unit 93, a howling suppression unit 94, and a speaker 95.
- the sound characteristic adjustment unit 92 receives a sound signal generated and collected by the first microphone 91a as an input, and adjusts the frequency and gain characteristics of the sound signal.
- an audio signal generated and collected by the second microphone 91b is adjusted in frequency and gain characteristics in the sound characteristic adjustment unit 92.
- the adjusted audio signals are mixed in the sound mixing unit 93.
- the sound characteristic adjustment unit 92 and the sound mixing unit 93 are, for example, as shown in FIG. It corresponds to such a commercially available mixer. FIG.
- the sound characteristic adjustment unit 92 includes, for example, an equalizer 921a, an equalizer 921b, an amplifier 922a, and an amplifier 922b.
- the equalizer 921a adjusts the frequency characteristic of the audio signal generated by collecting the sound with the first microphone 91a.
- the amplifier 922a adjusts the gain of the audio signal adjusted by the equalizer 921a.
- the equalizer 921b and the amplifying unit 922b adjust the frequency and gain characteristics of the audio signal generated and collected by the second microphone 91b.
- the sound characteristic adjustment unit 92 independently adjusts the frequency and gain characteristics of each audio signal collected by the first and second microphones 91a and 92b, similarly to a normal mixer.
- the audio signal mixed in the sound mixing unit 93 is input to the howling suppression unit 94.
- the howling suppression unit 94 performs signal processing for suppressing howling on the audio signal mixed in the sound mixing unit 93. Then, the signal-processed audio signal is appropriately amplified and amplified by the speaker 95.
- the howling suppression unit 94 corresponds to a howling suppression device that suppresses howling.
- the loudspeaker system is an example in which the howling suppression system disclosed in Patent Document 1 or Patent Document 2 is employed, and thus an adaptive filter or a notch filter is used as the howling suppression unit 94. You.
- FIG. 12 is a block diagram showing a configuration example of howling suppression section 94 using adaptive filter 941.
- the howling suppression unit 94 estimates a transfer characteristic such as a spatial transfer characteristic only when the sound signal is output, based on the sound signal (the sound signal to be loudspeaked) output from the howling suppression unit 94. I do.
- the applied filter 941 multiplies the estimated transmission characteristic by the audio signal to be loudspeaked, and subtracts it from the audio signal output from the sound mixing unit 93. Thereby, generation of howling can be suppressed.
- FIG. 13 is a diagram illustrating a change in power spectrum ⁇ ( ⁇ ) of the audio signal output from the sound mixing unit 93 when howling occurs.
- ⁇ power spectrum
- FIG. 13 changes so that the power sharply increases at the specific frequency f. Therefore, always observe the difference in power between adjacent bands As a result, it is detected that the power in the band including the specific frequency f has sharply increased. That is, the frequency at which howling occurs can be detected.
- the frequency at which the notch filter attenuates is set to the specific frequency f.
- the power of the specific frequency f is attenuated by passing the audio signal output from the sound mixing unit 93 through a notch filter attenuating at the specific frequency f. As a result, the occurrence of howling is suppressed.
- Patent Document 1 Japanese Patent No. 2039846
- Patent Document 2 Japanese Patent No. 2560923
- FIG. 14 is a diagram schematically showing characteristics of each component related to a transfer characteristic in the loudspeaker system 9 at the time of one input.
- the sound to be picked up by the microphone 91 is S ( ⁇ )
- the sound signal generated by picking up the sound by the microphone 91 is ⁇ ( ⁇ )
- the sound signal is adjusted by the sound characteristic adjusting unit 92.
- the frequency and gain characteristics are expressed by ⁇ ( ⁇ ), the ideal transfer characteristic to be estimated by the howling suppression unit 94 is Hhat ( ⁇ ), the audio signal output by the howling suppression unit 94 is also expressed by ⁇ ( ⁇ ), and the speaker 95
- R (co) be the spatial transfer characteristic from to the microphone 91.
- an audio signal X ( ⁇ ) generated by collecting sound by the microphone 91 is expressed by Expression (1).
- R (co) includes the characteristics of the microphone 91 itself, the characteristics of the speaker 95 itself, and the case where the signal is appropriately amplified between the output of the noise suppression unit 94 and the speaker 95, in addition to the transfer characteristics of the space described above. And its amplification characteristics may be included.
- the audio signal ⁇ ( ⁇ ) * ⁇ ( ⁇ ) adjusted by the sound characteristic adjustment unit 92 multiplies the output audio signal ⁇ ( ⁇ ) of the howling suppression unit 94 by the transfer characteristic Hhat ( ⁇ ). The subtraction is performed using the result, and the equation (2) is established.
- Equation (3) is obtained.
- the ideal transfer characteristic Hhat ( ⁇ ) is a transfer characteristic that satisfies Equation (4).
- FIG. 15 is a diagram schematically showing the characteristics of each component related to the transfer characteristics in the loudspeaker system 9 at the time of multiple inputs.
- the sound to be picked up by the first microphone 91a is S 1 ( ⁇ )
- the frequency and gain characteristics adjusted by the sound characteristic adjustment unit 92 are Ml ( ⁇ )
- the sound is Let Rl (co) be the spatial transfer characteristic up to the first microphone 91a.
- the sound to be picked up by the nth microphone is Sn (co)
- the frequency and gain characteristics adjusted by the sound characteristic adjustment unit 92 are ⁇ ( ⁇ )
- the speaker 95 outputs the nth microphone.
- the spatial transfer characteristic up to ON 92c is Rn (co).
- Equation (3) is expressed as Equation (5). Note that n is a natural number and indicates the number of microphones.
- the ideal transfer characteristic Hhat ( ⁇ ) to be estimated is a transfer characteristic that satisfies Equation (6).
- the spatial transfer characteristics R ( ⁇ ) of a plurality of audio signals are unique values.
- the space transfer characteristic R (co) is a value that changes depending on the position of the microphone. That is, in order to appropriately estimate the ideal transfer characteristics, it is necessary to consider the spatial transfer characteristics R (co) of each of the plurality of audio signals.
- the transfer characteristic is estimated based on the output signal of the howling suppression unit 94.
- the output signal of the howling suppression unit 94 is a signal based on an audio signal in which a plurality of audio signals are mixed, and is not a signal in which the spatial transfer characteristics R ( ⁇ ) of each of the plurality of microphones are considered. Therefore, conventionally, the estimated speed of the transfer characteristic cannot keep up with the change in the space transfer characteristic R (co), and the occurrence of howling cannot be appropriately suppressed. .
- the ideal transfer characteristic Hhat (t) to be estimated is a value determined by M ( ⁇ ) and R ( ⁇ ) of each of the plurality of microphones.
- the ideal transfer characteristic Hhat ( ⁇ ) is a value that changes as M ( ⁇ ) changes.
- the applied filter 941 estimates the transfer characteristic while converging based on the output signal of the howling suppression unit 94. Therefore, if ⁇ ( ⁇ ) changes abruptly and the ideal transfer characteristic Hhat ( ⁇ ) also changes abruptly, the estimated speed of the above transfer characteristics cannot keep up, and the occurrence of no and It was difficult to control.
- an object of the present invention is to detect a risk of howling occurrence for each of the plurality of audio signals in a loudspeaker system in which a plurality of audio signals are mixed and loudspeaked. Further, in the present invention, it is an object to estimate an appropriate transfer characteristic based on the information on the degree of risk and to suppress occurrence of a howling that is audible to a sudden change in the transfer characteristic by the sound characteristic adjustment unit. And Another object of the present invention is to provide a method for specifying and warning which audio signal of a plurality of input audio signals has generated howling or is in danger of generating it. . Means for solving the problem
- the first aspect of the present invention relates to howling generated when a mixed signal obtained by mixing a plurality of sound signals collected by a plurality of microphones in a sound mixing unit and loudspeaking the mixed signal by a speaker is used.
- a howling detection device for detecting a dominant ratio indicating a degree of danger of howling occurring for each signal, a level detection unit for detecting a level of each of the plurality of audio signals, and a signal related to sound amplified by the speaker Is used as a noise reference signal, the noise reference signal is compared with the mixed signal in a time-series manner, and an end time period in which the mixed signal is input after the noise reference signal is dropped is detected as an end section.
- a level of a plurality of audio signals detected by the level detection unit Only the level corresponding to the ending section is extracted, and the plurality of audio signals are extracted.
- a dominance ratio calculating unit that calculates a ratio of the level of each audio signal to the sum of the levels as the control ratio of each of the audio signals.
- the howling detection device is configured to control a signal included in the ending section based on a transfer characteristic calculated using the dominance rate. And a signal suppression unit that subtracts the signal having the same component as that of the mixed signal and outputs the signal to the speaker.
- the howling suppressing section estimates the mixed signal excluding a signal having the same component as a signal included in the ending section. And updating the sum according to the dominant rate, and multiplying the function by a change rate of the sum before and after the update to calculate the transfer characteristic.
- a fourth aspect of the present invention is characterized in that, in the third aspect, the howling suppression unit updates only the level of an audio signal indicating a relatively high dominance rate to update the sum.
- a fifth aspect of the present invention is characterized in that, in the third aspect, the howling suppression unit updates the sum by updating only the level of the audio signal exhibiting the highest dominance rate. I do.
- the howling detection device specifies an audio signal having a relatively high control rate calculated by the control rate calculation section, Is further provided.
- a seventh aspect of the present invention is the howling detection device according to the first aspect, wherein the howling detection device outputs the audio signal having the highest dominance ratio calculated by the dominance ratio calculation unit. It further includes a howling warning unit that specifies and notifies the user.
- the level detection section detects a plurality of the audio signal levels using a power spectrum.
- a ninth aspect of the present invention is to provide a loudspeaker for a howling generated when a mixed signal obtained by mixing a plurality of sound signals collected by a plurality of microphones in a sound mixing unit is amplified by a speaker.
- a howling detection device for detecting a dominant ratio indicating a degree of danger of howling occurring for each signal, a level detection unit for detecting a level of each of the plurality of audio signals, and calculating a power spectrum of the mixed signal.
- a howling occurrence detection unit that detects the occurrence of howling based on the change in the power spectrum; and a level when the occurrence of the howling is detected from the levels of the plurality of audio signals detected by the level detection unit.
- the howling detection device uses the signal related to the sound loudspeaked by the speaker as a noise reference signal, and uses the noise reference signal and the mixed signal as a noise reference signal. Based on a transfer characteristic calculated using the dominant ratio, and performing a sequential comparison and detecting the time at which the mixed signal is input after the noise reference signal has fallen as an end period.
- a howling suppression unit for subtracting the mixed signal power from a signal having the same component as the signal included in the ending section and outputting the signal to the speaker.
- the howling suppression unit estimates the mixed signal excluding a signal having the same component as a signal included in the ending section. Is set when the ending section is detected, the sum is updated in accordance with the dominance rate, and the transfer characteristic is multiplied by the rate of change of the sum before and after the update to change the transfer characteristic. Is calculated when is detected.
- the howling suppression section updates the sum by updating only the level of the audio signal indicating a relatively high dominance rate. It is characterized by.
- a thirteenth aspect of the present invention is characterized in that, in the eleventh aspect, the howling suppression unit updates the sum by updating only the level of the audio signal exhibiting the highest dominance rate.
- the howling detection device specifies an audio signal having a relatively high control rate calculated by the control rate calculation unit.
- the howling detection device specifies an audio signal having the highest dominance rate calculated by the dominance rate calculation unit, and notifies the user. It further includes a howling warning unit for notifying.
- the level detecting section detects a plurality of the audio signal levels using a power spectrum.
- a seventeenth aspect of the present invention is a method according to the present invention, wherein a plurality of microphones are mixed in a sound mixing step for each of the collected voice signals, and howling occurs when a mixed signal is amplified by a speaker.
- a howling detection method for detecting a dominant ratio indicating a degree of risk of generating howling for each of the audio signals wherein a level detection step for detecting the levels of the plurality of audio signals, respectively. Comparing the noise reference signal and the mixed signal in time series with a signal related to the sound amplified by the speaker as a noise reference signal, and calculating the time when the mixed signal is input after the noise reference signal has dropped.
- Ending detection step for detecting the ending as a ending section, and extracting only the level corresponding to the ending section from each of the plurality of level signals of the plurality of audio signals detected by the level detecting step. Calculating a ratio of the level of each audio signal to the sum of the levels of the audio signals as the dominant ratio of each of the audio signals.
- the eighteenth aspect of the present invention relates to a howling that occurs when a mixed signal obtained by mixing a plurality of microphone signals in a sound mixing step is amplified by a speaker.
- a howling detection method for detecting a dominance rate indicating a degree of danger of howling generation for each of the audio signals wherein a level detection step for detecting levels of a plurality of the audio signals, respectively,
- a howling occurrence detecting step of calculating a power spectrum and detecting the occurrence of howling based on a change in the power spectrum; and the levelers of the plurality of audio signals detected by the level detecting step also generate the howling. Is extracted, and the level of each audio signal level with respect to the sum of the levels of the plurality of audio signals is extracted.
- the ending section includes only a signal component that causes howling, and the dominance rate is calculated using a level corresponding to the ending section.
- the dominance is calculated based on the level of the audio signal before being mixed in the sound mixing unit.
- the risk level corresponding to the change is changed. Can be detected.
- the transfer characteristic is calculated using the dominant rate, so that a plurality of sounds can be obtained. It is possible to suppress howling according to the degree of danger of which voice signal generates howling among voice signals.
- the transfer characteristics are calculated using the dominant ratio, before being mixed by the sound mixing unit, for example, the frequency and Z or gain characteristics of a plurality of audio signals are respectively changed, and the transfer characteristics suddenly change. Even if it changes, robust howling can be suppressed in response to the change.
- the transfer characteristic is calculated based on the rate of change of the sum according to the dominant rate, robust howling considering the risk of causing howling of a plurality of audio signals is performed. Suppression can be achieved.
- a transfer characteristic corresponding to an audio signal having a relatively high risk of causing howling among a plurality of audio signals is calculated, so that highly efficient howling suppression can be achieved. Can be realized.
- a transfer characteristic corresponding to an audio signal having the highest risk of causing howling among a plurality of audio signals is calculated, thereby achieving highly efficient howling suppression. be able to. For example, it is rare for a user to change all the levels of multiple audio signals at the same time as a mixer operation, so even if the user follows only the one with the highest dominant ratio, robust howling can be suppressed. It can be carried out.
- the sixth aspect by specifying an audio signal having a relatively high dominance rate, which audio signal among a plurality of audio signals causes howling to the user. Can be notified if the risk is relatively high. Further, even if the user has a plurality of audio signals collected in an operation such as a mixer, the user can perform an operation while preventing howling from occurring by referring to the risk level.
- the user is less likely to risk howling of which audio signal among a plurality of audio signals. You can tell which is the highest. Further, even if there are a plurality of audio signals collected in the operation of the mixer or the like, the user can perform the operation while preventing howling from occurring by referring to the above-mentioned danger level.
- the level of a plurality of audio signals is calculated based on the power spectrum, so that the risk of generating howling can be detected for each frequency band.
- the ninth aspect when a howling occurs, it is possible to detect the degree of danger of which audio signal of the plurality of audio signals causes the howling.
- the control ratio is calculated based on the level of the audio signal before being mixed by the sound mixing unit.
- the transfer characteristic is calculated using the dominant rate, so that the ringing corresponding to the degree of danger of which audio signal among the plurality of audio signals causes howling is performed. Suppression can be performed.
- the transfer characteristics are calculated using the dominant ratio, before mixing in the sound mixing unit, for example, the frequency and Z or gain characteristics of a plurality of audio signals are respectively changed, and the transfer characteristics suddenly change. , Robust howling can be suppressed in accordance with the change.
- the transfer characteristic is calculated based on the change rate of the sum according to the dominance rate, so that a plurality of audio signals can be obtained before the ending section arrives.
- a transfer characteristic corresponding to an audio signal having a relatively high risk of causing howling among a plurality of audio signals is calculated, so that highly efficient howling suppression is achieved. Can be realized.
- a transfer characteristic corresponding to an audio signal having the highest risk of causing howling among a plurality of audio signals is calculated, thereby achieving highly efficient howling suppression. be able to. For example, it is rare for a user to change all the levels of multiple audio signals at the same time as a mixer operation, so even if the user follows only the one with the highest dominant ratio, robust howling can be suppressed. It can be carried out.
- the fourteenth aspect when a howling occurs, the user is notified of which of the plurality of audio signals the risk of causing the howling is relatively high. Can be. Further, even if the user has a plurality of audio signals picked up by operating a mixer or the like, the user can perform the operation while preventing howling from occurring by referring to the above-mentioned danger level. [0048] According to the fifteenth aspect, when a howling occurs, it is possible to notify the user which of the plurality of audio signals has the highest risk of causing the howling. . Further, even if there are a plurality of audio signals collected by the user in the operation of, for example, a mixer, the user can perform the operation while preventing howling from occurring by referring to the risk level.
- the level of a plurality of audio signals is calculated from the power spectrum, so that the risk of generating howling can be detected for each frequency band.
- FIG. 1 is a block diagram showing a configuration example of a loudspeaker system 1.
- FIG. 2 is a block diagram showing a configuration example of a sound characteristic adjustment unit 12 and a sound mixing unit 13
- FIG. 3 is a diagram showing waveforms of a noise reference signal Y (t) and a speech signal Xm (t).
- FIG. 4 is a diagram showing an example of a spectrum of loop gains G1 ( ⁇ ), G2 ( ⁇ ), and the sum of loop gains (G1 ( ⁇ ) + G2 ( ⁇ )).
- FIG. 5 is a block diagram showing an example of a configuration of a howling suppression section 17.
- FIG. 6 is a block diagram showing a configuration example of a loudspeaker system 2.
- FIG. 7 is a block diagram illustrating an example of a configuration of a howling suppression unit 22 according to the second embodiment.
- FIG. 8 is a block diagram showing a configuration example of a howling warning device.
- FIG. 9 is a block diagram showing a configuration example of a howling warning device using a howling occurrence detection unit 21.
- FIG. 10 is a diagram showing a configuration example in which a howling suppression device disclosed in Patent Document 1 and Patent Document 2 is adopted in a loudspeaker system 9 for mixing and vocalizing a plurality of audio signals.
- FIG. 11 is a block diagram showing a configuration example of a sound characteristic adjustment unit 92 and a sound mixing unit 93.
- FIG. 12 is a block diagram showing an example of a configuration of a ringing suppression unit 94 using an adaptive filter 941.
- FIG. 12 is a block diagram showing an example of a configuration of a ringing suppression unit 94 using an adaptive filter 941.
- FIG. 13 is a diagram showing a change in power spectrum ⁇ ( ⁇ ) of the audio signal output from the sound mixing section 93 when a ringing occurs.
- FIG. 14 is a diagram schematically showing characteristics of each component related to transfer characteristics in the loudspeaker system 9 with one input.
- FIG. 15 is a diagram schematically showing characteristics of respective components related to transfer characteristics in the loudspeaker system 9 at the time of plural inputs.
- FIG. 1 is a block diagram showing a configuration example of the loudspeaker system 1.
- the loudspeaker system 1 includes a first microphone l la, a second microphone l lb, a sound characteristic adjustment unit 12, a sound mixing unit 13, a level detection unit 14, a ending detection unit 15, a dominance rate calculation unit 16, It has a howling suppression unit 17 and a speaker 18.
- the loudspeaker system 1 may be a system for loudspeaking using three or more microphones. However, here, a description will be given assuming a case where loudspeakers are used for two microphones.
- a first microphone 11a collects a sound to be amplified by a speaker 18 and generates a sound signal.
- the audio signal generated by the first microphone 11a is defined as XI (t).
- the second microphone lib also collects a sound for loudspeaking and generates a sound signal X2 (t).
- the sound characteristic adjustment unit 12 receives the audio signals XI (t) and X2 (t) as inputs, and adjusts the frequency and gain characteristics of the audio signal, respectively.
- the audio signal XI (t) adjusted by the audio characteristic adjustment unit 12 is defined as Xml (t).
- the audio signal X2 (t) adjusted by the sound characteristic adjustment unit 12 is defined as Xm2 (t).
- the audio signals Xml (t) and Xm2 (t) adjusted by the sound characteristic adjustment unit 12 are output to the level detection unit 14 and the sound mixing unit 13, respectively.
- the audio signals Xml (t) and Xm2 (t) input to the sound mixing unit 13 are mixed in the sound mixing unit 13. Let this mixed audio signal be Xm (t).
- the sound signal Xm (t) mixed in the sound mixing unit 13 is output to the ending detection unit 15 and the howling suppression unit 94.
- the sound characteristic adjusting unit 12 and the sound mixing unit 13 are, for example, commercially available mixers as shown
- FIG. 2 is a block diagram showing a configuration example of the sound characteristic adjustment unit 12 and the sound mixing unit 13.
- the sound characteristic adjustment unit 12 includes, for example, an equalizer 121a, an equalizer 121b, an amplifier 122a, and an amplifier 122b.
- the equalizer 121a adjusts the frequency characteristics of the audio signal XI (t) generated by collecting the sound with the first microphone 11a.
- the amplifier 122a adjusts the gain of the audio signal adjusted by the equalizer 121a.
- equalizer 121b The amplifying unit 122b adjusts the frequency and gain characteristics of the audio signal X2 (t) generated and collected by the second microphone lib.
- the sound characteristic adjustment unit 12 independently adjusts the frequency and gain characteristics of each audio signal collected by the first and second microphones 11a and 12b, similarly to a normal mixer. .
- Level detection unit 14 detects each level of audio signals Xml (t) and Xm2 (t) output from sound characteristic adjustment unit 12. As a specific detection method, for example, a power spectrum is calculated every predetermined time, and a level for each band is detected. All the information on the level for each band at each predetermined time detected by the level detection unit 14 is output to the dominance ratio calculation unit 16.
- the ending detection unit 15 Based on the speech signal Xm (t) input from the sound mixing unit 13 and the noise reference signal Y (t), the ending detection unit 15 generates the speech signal Xm for the noise reference signal Y (t). The delay section of the voice section of (t) is detected as the ending.
- the noise reference signal Y (t) is a signal related to the sound loudspeaked by the speaker, and is, for example, an audio signal immediately before loudspeaker 18.
- the noise reference signal Y (t) is also input to the howling suppression unit 17 for the input force immediately before the speaker 18.
- the sound signal may be a sound signal generated by collecting the sound loudspeaked near the speaker 18 by another microphone or the like.
- howling suppression section 17 is connected to the other microphone, and inputs a speech signal output from the other microphone as noise reference signal Y (t).
- FIG. 3 is a diagram showing waveforms of the noise reference signal Y (t) and the audio signal Xm (t).
- the speech section of the speech signal Xm (t) is delayed with respect to the noise reference signal Y (t). This is because, as shown in Fig. 13 and Equation 1, in addition to the voice S ( ⁇ ) uttered by the speaker, the voice signal generated by the microphone picked up This is because speech ⁇ ( ⁇ ) * R (co) which is mixed into the microphone again is included. That is, the mixed sound ⁇ ( ⁇ ) * R (co) is delayed from the loudspeaker 18 by the amount of spatial propagation.
- the audio signal Xm (t) is spatially propagated and mixed again with the first microphone 11a and / or the second microphone lib.
- the delayed voice ⁇ ( ⁇ ) * R (co) contains a signal component.
- the ending part shown in FIG. 3 contains only signal components that are spatially propagated and mixed again into the first microphone 11a and / or the second microphone 1lb.
- the dominance rate calculating unit 16 described later transmits only the signal components that are spatially propagated and mixed again into the first microphones 11a and Z or the second microphone lib. Based on! /, You can calculate the dominance rate.
- the ending detection unit 15 As a specific detection method of the ending detection unit 15, for example, there is a method of using a power envelope of the waveform of the audio signal Xm (t) and the noise reference signal Y (t). The end part can be detected by constantly observing the ratio using each power envelope (excluding the rising part). Further, for example, the ending detection unit 15 compares the noise reference signal Y (t) and the speech signal Xm (t) in a time-series manner. Then, the ending detection unit 15 detects the falling edge of each power envelope, and uses the difference between them as the ending part. Information on the ending (delayed portion) detected by the ending detecting unit 15 is sent to the dominant ratio calculating unit 16 and the howling suppressing unit 17.
- the dominance rate calculation unit 16 determines a plurality of input audio signals (FIG. 1) based on the level of each audio signal output from the level detection unit 14 and the ending detected by the ending detection unit 15. Let us calculate the dominance of Xml (t) and Xm2 (t) respectively. Note that the dominant rate calculating unit 16 performs the dominant rate calculating process only in the ending section detected by the ending detecting unit 15. Hereinafter, a method of calculating the control rate will be specifically described.
- the dominance rate indicates the degree of danger of howling for each of a plurality of audio signals.
- the power spectrum of the ending section is defined as a loop gain G.
- the loop gain of the audio signal Xml (t) is Gl ( ⁇ )
- the loop gain of the audio signal Xm2 (t) is G2 ( ⁇ ).
- the sound signal Xmn (t) is input from the ⁇ -th ( ⁇ is a natural number) microphone and the frequency and gain characteristics are adjusted by the sound characteristic adjustment unit 12.
- the loop gain Gn (co) of the Xmn (t) can be expressed by Expression 7.
- the dominance rate calculation unit 16 extracts the level gain G, which is the level of the ending section of the level power of each audio signal, and determines, for example, the loop rate of all audio signals as the dominance rate for each audio signal.
- the ratio between the sum of the gains and the loop gain of each audio signal is calculated.
- the sum of the loop gains is G1 ( ⁇ ) + G2 ( ⁇ ). Therefore, the dominance rate for the audio signal Xml (t) is expressed as a ratio between the sum (G1 ( ⁇ ) + G2 ( ⁇ )) and Gl ( ⁇ ).
- the dominance rate for the audio signal Xm2 (t) is expressed as the ratio between the sum (G1 ( ⁇ ) + G2 ( ⁇ )) and G2 ( ⁇ ).
- FIG. 4 is a diagram illustrating an example of the spectrum of the loop gains Gl (co), G2 ( ⁇ ), and the sum of the loop gains (G1 ( ⁇ ) + G2 ( ⁇ )).
- the dominance of G2 (co) increases in a frequency band higher than the frequency, and it is determined that G2 (co) is dominant.
- the dominance of G1 ( ⁇ ) increases, and it is determined that G1 ( ⁇ ) is dominant.
- the dominant rate calculation unit 16 calculates the dominant rate of each audio signal for the ending section including only the spatially propagated signal component, so that which audio signal is dominant. Can be detected.
- the spatially propagated signal component is a signal component that causes howling. Therefore, for example, the dominant ratio calculating unit 16 determines whether the sound transmitted through the path of R1 ( ⁇ ) shown in FIG. 13 is dominant or the sound transmitted through the path of R2 ( ⁇ ) is dominant before the howling occurs, for example. Can be detected. The more dominant the voice signal, the higher the risk of howling.
- the sound characteristic adjusting unit 12, the sound mixing unit 13, the level detecting unit 14, the ending detecting unit 15, and the dominant ratio calculating unit 16 correspond to a howling detecting device according to the present invention. Then, the howling detection device according to the present invention can detect the risk of causing howling for each of the plurality of audio signals by calculating the dominant ratio.
- the timing of learning the dominance rate is not limited to the timing of learning each time a ending is detected, and may be appropriately adjusted in consideration of the sequentiality and accuracy of estimation.
- the howling suppression unit 17 applies the audio signal Xm (t) mixed in the sound mixing unit 13 to the Then, signal processing for suppressing howling is performed.
- the signal-processed audio signal is appropriately amplified and amplified by the speaker 18.
- FIG. 5 is a block diagram illustrating an example of the configuration of the howling suppression unit 17.
- a two-input subtraction configuration is employed.
- the 2-input subtraction configuration suppresses the occurrence of howling by using the audio signal to be loudspeaked as a noise reference signal, learning the transfer characteristics according to the endings contained in the audio signal to be loudspeaked, and be able to.
- howling suppression section 17 includes first power spectrum calculation section 171, second power spectrum calculation section 172, transmission characteristic calculation section 173, inverse Fourier transform section 174, and convolution section 175.
- first power spectrum calculating section 171 receives audio signal Xm (t) output from sound mixing section 13 as input, and calculates power spectrum ⁇ ( ⁇ ) of audio signal Xm (t). I do.
- Second power spectrum calculation section 172 receives noise reference signal Y (t) as input, and calculates power spectrum ( ⁇ ) of noise reference signal Y (t).
- the voice signal to be loudspeaked as the noise reference signal Y (t) is, for example, a voice signal immediately before being loudspeaked by the speaker 18.
- the sound signal may be a sound signal generated by collecting a sound amplified in the vicinity of the speaker 18 with a microphone or the like.
- the transfer characteristic calculating section 173 firstly outputs the power spectrum ratio Hr ( ⁇ ) to the ending detection section 15 based on the voice signal Xm (co) and the noise reference signal ⁇ ( ⁇ ). Estimate only between detected endings.
- the power spectrum ratio Hr ( ⁇ ) is expressed by Expression (8).
- transfer characteristic calculating section 173 calculates transfer characteristic Hsup ( ⁇ ) shown in Expression (9) based on the power vector ratio Hr ( ⁇ ) estimated by Expression (8).
- Hsup ( ⁇ ) is the same as the signal included in the ending section. This is a function for estimating the speech signal Xm (t) by removing the signal having the minute component.
- the transfer characteristic calculating section 173 calculates the loop gain of each audio signal calculated by the dominant rate calculating section 16 and the loop gain obtained based on the dominant rate by adding Hsup (co) calculated by Expression 9 to Hsup (co). Multiply the rate of change of the sum to calculate Hsup (co).
- Hsup (co) a method of calculating Hsup (co) will be described.
- the user changes the frequency and gain characteristics of the audio signals XI (t) and X2 (t) by performing a mixer operation in the sound characteristic adjustment unit 12 and the sound mixing unit 13, respectively.
- the frequency and gain characteristics Ml ( ⁇ ) of the audio signal Xml (t) and the frequency and gain characteristics M2 ( ⁇ ) of the audio signal Xm2 (t) change.
- the loop gains Gl (co) and G2 (co) also change.
- the dominant rate of the loop gain G1 ( ⁇ ) calculated by the dominant rate calculating unit 16 before the mixer operation is higher than the loop gain G2 (co).
- the loop gain G1 ( ⁇ ) calculated by the control ratio calculation unit 16 after the mixer operation is set as the loop gain Glnew ( ⁇ ), and the loop gain G1 ( ⁇ ) calculated by the control ratio calculation unit 16 before the mixer operation is looped.
- the gain is assumed to be Glold ( ⁇ ).
- the loop gain G2 ( ⁇ ) calculated by the control ratio calculation unit 16 after the mixer operation is set as a loop gain G 2 ew ( ⁇ ), and the loop gain G2 ( ⁇ ) calculated by the control ratio calculation unit 16 before the mixer operation is set. ) Is the loop gain G2old ( ⁇ ).
- the sum of the loop gains calculated by the dominance ratio calculation unit 16 before the operation of the mixer is Glold (co) + G2old (co).
- the sum of the loop gains calculated by the dominance ratio calculation unit 16 after the mixer operation is a sum considering only the loop gain with the highest dominance ratio among the dominance ratios calculated before the mixer operation. That is, in the above description, since the dominant rate of the loop gain G1 ( ⁇ ) is higher than the loop gain G2 ( ⁇ ), the sum of the loop gains calculated by the dominant rate calculating unit 16 after the mixing operation is Glnew (co) + G2old (co). At this time, the rate of change Lr (co) of the sum of the loop gains is represented by Expression 10.
- the loop gain and the dominance of each audio signal calculated by the dominance rate calculating unit 16 are calculated. Based on the rate, the change rate Lr (co) of the sum of the loop gains is obtained.
- the rate of change Lr ( ⁇ ) of the sum of the loop gains the dominant rate is the highest, and the sum of the norape gains (G1 ( ⁇ ) old + G2 ( ⁇ ) old) according to the change in the loop gain G1 ( ⁇ ) Can be expected to have changed to a sum (Gl ( ⁇ ) new + G2 ( ⁇ ) old).
- the loop gain with the highest dominance ratio is reflected in the sum of the loop gains.
- the transfer characteristic calculation unit 173 multiplies the transfer characteristic Hsup (co) calculated by Expression (9) by the change rate of the sum of the loop gains shown by Expression (10), and obtains the transfer characteristic according to the change rate of the sum. Hsup—ne w ( ⁇ ) is calculated. Note that the transfer characteristic Hsup ( ⁇ ) is Hsup_old ( ⁇ ), and the transfer characteristic according to the rate of change of the sum is Hsup-new (co). At this time, the transfer characteristic Hsup_new (co) according to the change rate of the sum is expressed by Expression (11).
- H sup — new (w) L r ( ⁇ ) * H sup . ld ( ⁇ ) ⁇ ⁇ (1 1)
- the transfer characteristic Hsup-new (co) according to the change rate of the sum is a transfer characteristic obtained by multiplying the estimated function Hsup ( ⁇ ) -old by the change rate of the sum. is there.
- the Hsup-new (co) updated by Expression (11) is transformed on the time axis by the inverse Fourier transform unit 174.
- the Hsup-new ( ⁇ ) converted on the time axis is referred to as a filter coefficient Hsup-new (t).
- the convolution unit 175 convolves the filter coefficient Hsup—new (t) into the audio signal Xm (t) input from the sound mixing unit 13 to obtain a signal only in the ending section detected by the ending detection unit 15.
- the signal containing only the same component as is subtracted from the audio signal Xm (t).
- the calculation (Equation 9) and the update (Equation 11) of Hsup (co) are performed when the ending detection unit 15 detects the ending.
- calculation of Hsup (co) The learning of the equations (9) and (11)) may be performed, for example, by a predetermined method every time the ending is detected.
- the dominant ratio calculating unit 16 calculates the loop gain and the dominant ratio of each audio signal, and based on the dominant ratio, changes the sum of the! Calculate the transfer characteristics using the conversion rate. Further, the dominance rate is calculated based on the output signal of the sound characteristic adjustment unit 12, and is a value linked to the frequency-gain characteristic adjusted by the sound characteristic adjustment unit 12.
- a transfer characteristic used for suppressing howling is calculated based on the dominant ratio, whereby the transfer characteristic of the sound characteristic adjustment unit 12 is calculated. Robust howling can be suppressed against sudden changes in the temperature. That is, robust howling can be suppressed against a rapid change in ⁇ ( ⁇ ) due to the user's mixer operation.
- the sum of the time-varying component loop gain of only the loop gain having the highest dominant rate is estimated. It is not limited to this. For example, a plurality of loop gains having a relatively high dominance ratio may be reflected in the sum of the loop gains. For example, suppose there are three microphones, and their loop gains are G1 ( ⁇ ), G2 ( ⁇ ), and G3 ( ⁇ ). Then, it is assumed that the relationship between the dominant rates before the mixer operation is such that the loop gains G1 ( ⁇ ) and G2 ( ⁇ ) are higher than the loop gain G3 ( ⁇ ).
- the loop gains G1 ( ⁇ ) and G2 ( ⁇ ) may be reflected in the sum of the loop gains (G1 ( ⁇ ) + G2 ( ⁇ ) + G3 ( ⁇ )).
- the change rate Lr (co) of the sum of the loop gains is represented by Expression 12.
- the transfer characteristic calculating section 173 calculates the change rate of the sum of the loop gains by using the dominant rate calculated by the dominant rate calculating section 16 and reflecting the dominant rate on each loop gain of each audio signal. May be. Further, for example, the transfer characteristic calculating unit 173 may calculate the transfer characteristic used for suppressing the noise by a method other than the change rate of the sum of the loop gains, based on the dominant ratio.
- the present invention is not limited to this.
- the specific configuration of the subtraction is not limited to the force shown in FIG.
- a number of subtraction methods other than the convolution filter method are also known, and a configuration using these methods may be used.
- the level detection unit 14 performs frequency analysis on each audio signal, and calculates the level as a power spectrum.
- the power is not limited to this.
- the level detection unit 14 may calculate the power of each audio signal every predetermined time as a scalar value.
- the dominant ratio calculating unit 16 calculates the dominant ratio of each audio signal as a scalar value.
- the rate of change Lr (co) of the sum of the loop gains is also represented by a scalar value.
- FIG. 6 is a block diagram illustrating a configuration example of the loudspeaker system 2.
- the loudspeaker system 2 includes a first microphone l la, a second microphone l lb, a sound characteristic adjustment unit 12, a sound mixing unit 13, a level detection unit 14, a howling occurrence detection unit 21, a dominance ratio calculation unit 16 , A howling suppressing unit 22 and a speaker 18.
- the dominance rate of each audio signal is calculated only in the ending section. However, this embodiment is different in that it is calculated when howling is detected.
- the loudspeaker system 2 may be a system that loudspeakers using three or more microphones! /, But here, the description will be made assuming that loudspeakers are used using two microphones. I do.
- the first microphone 11a collects a sound to be loudspeaked by the speaker 18, and generates a sound signal.
- the audio signal generated by the first microphone 11a be XI (t).
- the second microphone l ib also collects a sound for loudspeaking and generates a sound signal X2 (t).
- the sound characteristic adjustment unit 12 receives the audio signal XI (and X2 (t) as an input, and adjusts the frequency and gain characteristics of the audio signal, respectively. Then, the audio signal Xml ( t) and Xm2 (t) are mixed in the sound mixing unit 13.
- the level detection unit 14 includes a sound characteristic adjustment unit 12 Detects the levels of the output audio signals Xml (t) and Xm2 (t). Then, all the level information for each band detected by the level detection unit 14 for each predetermined time is output to the control ratio calculation unit 16. The processing up to this point is the same as in the above-described first embodiment.
- Howling occurrence detecting section 21 calculates the power spectrum Xm (co) of audio signal Xm (t) mixed by sound mixing section 13, and detects howling occurrence. For example, assuming that howling occurs at a specific frequency f, the power spectrum ⁇ ( ⁇ ) of the audio signal Xm (t) changes so that the power rapidly increases at the specific frequency f as shown in Fig. 13. . Therefore, by constantly observing the difference in power between adjacent bands, it is detected that the power of the band including the specific frequency f has rapidly increased. In other words, the power spectrum ⁇ ( ⁇ ) of the audio signal Xm (t) is observed, and the initial generation of howling (a state in which noling occurs or is being applied) is detected. Then, the information at the time of the initial occurrence of the howling detected by the howling occurrence detecting section 21 is output to the dominant rate calculating section 16.
- the dominance rate calculation unit 16 is configured to input a plurality of input audio signals (see FIG. 10) based on the level of each audio signal output from the level detection unit 14 and the information detected by the howling occurrence detection unit 21.
- step 6 the control rates of Xml (t) and Xm2 (t) are calculated.
- the dominant rate calculating section 16 performs a dominant rate calculating process when the howling occurrence detecting section 21 detects the initial occurrence of howling. Then, of the levels calculated by the level detection unit 14, the power spectrum when the initial occurrence of howling is detected becomes the loop gain G.
- a specific calculation method of the dominant ratio is the same as that of the first embodiment, and thus the description thereof is omitted.
- the dominant ratio of each audio signal is calculated by the dominant ratio calculating section 16, so that it is possible to detect which audio signal is dominant at the initial occurrence of howling.
- the dominance rate in the present embodiment indicates the degree of risk of causing howling for each of a plurality of audio signals, as in the first embodiment.
- the sound characteristic adjustment unit 12, the sound mixing unit 13, the level detection unit 14, the howling occurrence detection unit 21, and the dominant ratio calculation unit 16 correspond to a sampling detection device in the present invention. That is, the howling detection device according to the present invention generates howling for each of the plurality of audio signals by calculating the dominant ratio. The degree of danger to be generated can be detected.
- FIG. 7 is a block diagram illustrating an example of the configuration of the howling suppression unit 22 according to the second embodiment.
- howling suppressing section 22 includes first power spectrum calculating section 171, second power spectrum calculating section 172, transfer characteristic calculating section 173, inverse Fourier transform section 174, convolution section 175, and ending detection section 176. Yes.
- the power howling suppression section 22 that has referred to the ending information from the ending detection section 15 has a new ending detection section 176, and the ending detection section 176 refers to the ending information.
- the ending detection section 176 refers to the ending information.
- first power spectrum calculating section 171 receives audio signal Xm (t) output from sound mixing section 13 as input, and calculates power spectrum ⁇ ( ⁇ ) of audio signal Xm (t). I do.
- Second power spectrum calculation section 172 receives noise reference signal Y (t) as input, and calculates power spectrum Y ( ⁇ ) of noise reference signal Y (t).
- the end detection unit 176 has the same function as the end detection unit 15 described above.
- the ending detection unit 176 generates a speech signal Xm (t) corresponding to the noise reference signal Y (t) based on the speech signal Xm (t) input from the sound mixing unit 13 and the noise reference signal Y (t).
- the delay section of the voice section is detected as the ending.
- the noise reference signal Y (t) is, for example, an audio signal immediately before being loudspeaked by the speaker 18 as in the first embodiment described above.
- the ending detection unit 176 may be provided inside the howling suppression unit 17 and may be provided outside the force howling suppression unit 17. Also, the howling suppression unit 17 and the ending detection unit 176 may be separately provided so that the howling suppression unit 17 inputs information detected by the ending detection unit 176.
- the transfer characteristic calculating section 173 first calculates the power spectrum ratio Hr ( ⁇ ) shown in Expression 8 based on the voice signal Xm (co) and the noise reference signal ⁇ ( ⁇ ) based on the V and the ending detection section 176. Then, the estimation is performed only in the section of the ending detected. Then, the transfer characteristic calculation unit 173 estimates Based on the power spectrum ratio Hr ( ⁇ ), the transfer characteristic Hsup ( ⁇ ) shown in Expression (9) is calculated. Next, the transfer characteristic calculating section 173 obtains the transfer characteristic Hsup (co) calculated by the equation (9) using V based on the loop gain and the dominant rate of each audio signal calculated by the dominant rate calculating section 16.
- the transfer characteristic Hsu p ( ⁇ ) —new is calculated according to the change rate by multiplying the change rate of the sum of the obtained loop gains. Then, the transfer characteristic Hs up_new (co) according to the change rate calculated by Expression 11 is transformed on the time axis by the inverse Fourier transform unit 174.
- the convolution unit 175 convolves the filter coefficient Hsup—new (t) converted on the time axis with the speech signal Xm (t) input from the sound mixing unit 13, The signal containing only the same component as the signal of only the ending section is subtracted from the voice signal Xm (t).
- the transfer characteristic Hsup ( ⁇ ) —new according to the rate of change is based on the rate of change of the sum of the loop gains obtained using the loop gain at the initial occurrence of howling. Therefore, it is possible to suppress howling in consideration of an audio signal in which initial occurrence of howling occurs and its frequency component.
- the calculation of Hsup ( ⁇ ) (Equation (9)) is performed when the ending is detected by the ending detecting unit 176. Updating of Hsup ( ⁇ ) based on the change rate of the sum of the loop gains based on the dominant rate (Equation (11)) is performed when the howling occurrence detection unit 21 detects the initial occurrence of howling. Further, the learning of Hsup ( ⁇ ) calculated by Expression 9 may be performed by a predetermined method every time the ending is detected, for example. Further, learning of Hsup (co) calculated by Expression 11 may be performed by a predetermined method every time an initial occurrence of howling is detected, for example.
- the dominant ratio calculating unit 16 calculates the loop gain and the dominant ratio of each audio signal at the time of the initial occurrence of howling. Then, the transfer characteristic is calculated based on the change rate of the sum of the loop gains based on the dominant rate. Further, since the dominant ratio is calculated based on the output signal of the sound characteristic adjustment unit 12, it is a value linked to the frequency and gain characteristics adjusted in the sound characteristic adjustment unit 12. In this way, in a loudspeaker system in which a plurality of audio signals are mixed and loudspeaked, the transfer characteristic used for howling suppression is calculated based on the above dominant ratio, whereby the sound characteristic adjustment unit 12 Robust howling can be suppressed against howling caused by a sudden change in transfer characteristics.
- M ( ⁇ ) caused by the user's operation of the mixer
- FIG. 8 is a block diagram showing a configuration example of the howling warning device.
- the howling warning device includes a first microphone lla, a second microphone llb, a sound characteristic adjustment unit 12, a sound mixing unit 13, a level detection unit 14, a ending detection unit 15, and a dominance ratio calculation unit. 16, a speaker 18, and a howling warning section 31 are provided.
- FIG. 9 is a block diagram illustrating a configuration example of a howling warning device using the howling occurrence detection unit 21.
- the howling warning device includes a first microphone l la, a second microphone l lb, a sound characteristic adjustment unit 12, a sound mixing unit 13, a level detection unit 14, a howling occurrence detection unit 21, a dominant ratio calculation unit. 16, a speaker 18, and a noise warning unit 31.
- the present embodiment is different from the first and second embodiments in that a howling warning unit 31 is provided instead of the howling suppression units 17 and 22 in the first and second embodiments.
- the above-described howling detection apparatus according to the present invention includes the howling warning unit 31.
- the speed 18 is the same as in the first and second embodiments described above.
- howling warning section 31 warns the user of a power at which howling is likely to occur due to which audio signal, according to the dominant rate based on the ending section calculated by dominant rate calculating section 16.
- a display means for giving a warning for example, means for setting a lamp on each channel of a mixer for adjusting the frequency and gain characteristics of an audio signal and blinking a channel which may cause howling, etc. There is. Then, for example, the audio signal with the highest dominance (high risk of howling) Blink the channel lamp. Further, for example, the lamps of a plurality of channels having a high dominance ratio may be blinked.
- a lamp for each frequency band may be provided for each channel, and the lamp may blink for each band.
- the display means is not limited to the above-mentioned lamp, and may be a means for displaying on a display or other display means.
- the sound characteristics may be automatically changed by the sound characteristics adjustment unit 12 (for example, the gain is reduced) in response to the warning which is not merely a warning, and howling may be prevented beforehand.
- a warning may be given to the user as to which audio signal is likely to cause howling due to the dominant rate based on the initial occurrence of howling.
- the howling warning unit 31 refers to the dominant ratio based on the initial occurrence of the ringing and the ringing calculated by the dominant ratio calculating unit 16 to inform the user which audio signal is causing the initial occurrence of howling. Can warn.
- howling warning section 31 has a power at which howling is likely to be caused by howling signal depending on the dominant rate calculated by dominant rate calculating section 16 or The user is warned which audio signal causes the initial occurrence of howling.
- the user can perform a mixer operation or the like on each audio signal while preventing howling from occurring.
- the level detection unit 14, the ending detection unit 15, the dominance ratio calculation unit 16, and the howling suppression unit 17 described in the first embodiment are, for example, a sound signal output from the sound characteristic adjustment unit 12 (see FIG. In FIG. 1, Xml (t) and Xm2 (t)), the audio signal output from the sound mixing unit 13 (Xm (t) in FIG. 1), and the noise reference signal (Y (t) in FIG.
- the level detection unit 14, the howling occurrence detection unit 21, the dominant ratio calculation unit 16, and the howling suppression unit 17 described in the second embodiment described above include, for example, audio output from the sound characteristic adjustment unit 12.
- the audio signal (Xm (t) in Fig. 6) and the noise reference signal (Y (t) in Fig. 6) are also input, and the audio signal processing result is amplified by an amplifying unit as appropriate.
- An integrated circuit that outputs to 18 is also feasible.
- the level detection unit 14, the ending detection unit 15, and the dominance ratio calculation unit 16 described in FIG. 8 of the third embodiment described above are, for example, audio signals (FIG. 8) output from the sound characteristic adjustment unit 12.
- FIG. 8 Xml (t) and Xm2 (t)) and the audio signal (Xm (t) in FIG. 8) output from the sound mixing unit 13 are input, and the result of the audio signal processing is indicated by the howling warning unit.
- An integrated circuit outputting to 31 can also be realized.
- the level detection unit 14, the howling occurrence detection unit 21, and the dominant ratio calculation unit 16 described with reference to FIG. 9 of the third embodiment described above include, for example, an audio signal output from the sound characteristic adjustment unit 12 (see FIG.
- the electric circuits that perform the above-described functions are integrated in one small package to form, for example, an audio signal processing circuit DSP (Digital Signal Processor). Thereby, the present invention can be realized.
- DSP Digital Signal Processor
- the howling detection apparatus and method according to the present invention mixes a plurality of audio signals capable of detecting the degree of danger of howling occurrence for each of the plurality of audio signals by calculating a dominant ratio. It is also useful for loudspeaker systems and PA equipment with a sound mixer function.
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Abstract
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US11/579,133 US7912230B2 (en) | 2004-06-16 | 2005-06-15 | Howling detection device and method |
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JP3516227B2 (ja) * | 1997-11-10 | 2004-04-05 | ヤマハ株式会社 | ハウリング抑止装置 |
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JP3984842B2 (ja) * | 2002-03-12 | 2007-10-03 | 松下電器産業株式会社 | ハウリング制御装置 |
WO2005125272A1 (ja) * | 2004-06-16 | 2005-12-29 | Matsushita Electric Industrial Co., Ltd. | ハウリング抑圧装置、プログラム、集積回路、およびハウリング抑圧方法 |
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- 2005-06-15 WO PCT/JP2005/010959 patent/WO2005125273A1/ja active Application Filing
- 2005-06-15 CN CN2005800138788A patent/CN1951147B/zh not_active Expired - Fee Related
- 2005-06-15 US US11/579,133 patent/US7912230B2/en not_active Expired - Fee Related
- 2005-06-15 JP JP2006514765A patent/JP4675888B2/ja not_active Expired - Fee Related
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JPH0833091A (ja) * | 1994-07-18 | 1996-02-02 | Roland Corp | ハウリング予知装置 |
JPH08223274A (ja) * | 1995-02-15 | 1996-08-30 | Matsushita Electric Works Ltd | ハンズフリー通話装置 |
JP2002223182A (ja) * | 2000-11-22 | 2002-08-09 | Nippon Telegr & Teleph Corp <Ntt> | 反響消去方法、その装置、そのプログラム及びその記録媒体 |
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JP2007274641A (ja) * | 2006-03-31 | 2007-10-18 | Yamaha Corp | 音響処理装置 |
JP2007274640A (ja) * | 2006-03-31 | 2007-10-18 | Yamaha Corp | 音響処理装置 |
JP2009188442A (ja) * | 2008-02-01 | 2009-08-20 | Iwate Univ | ハウリング抑制装置、ハウリング抑制方法及びハウリング抑制プログラム |
WO2010035760A1 (ja) * | 2008-09-24 | 2010-04-01 | ヤマハ株式会社 | ループゲイン推定装置およびハウリング防止装置 |
JP2010081085A (ja) * | 2008-09-24 | 2010-04-08 | Yamaha Corp | ハウリング防止装置、マイクロフォン、ミキサ、およびアダプタ |
US8917885B2 (en) | 2008-09-24 | 2014-12-23 | Yamaha Corporation | Loop gain estimating apparatus and howling preventing apparatus |
JP2010130070A (ja) * | 2008-11-25 | 2010-06-10 | Yamaha Corp | ループゲイン推定装置 |
JP2010157806A (ja) * | 2008-12-26 | 2010-07-15 | Yamaha Corp | ハウリング防止装置 |
JP2010263600A (ja) * | 2009-04-09 | 2010-11-18 | Yamaha Corp | ハウリング防止装置 |
JP2010245992A (ja) * | 2009-04-09 | 2010-10-28 | Yamaha Corp | ハウリング防止装置 |
WO2011007812A1 (ja) * | 2009-07-17 | 2011-01-20 | ヤマハ株式会社 | ハウリングキャンセラ |
US8995682B2 (en) | 2009-07-17 | 2015-03-31 | Yamaha Corporation | Howling canceller |
US9002029B2 (en) | 2009-07-17 | 2015-04-07 | Yamaha Corporation | Howling canceller |
WO2019160006A1 (ja) * | 2018-02-16 | 2019-08-22 | 日本電信電話株式会社 | ハウリング抑圧装置、その方法、およびプログラム |
JPWO2019160006A1 (ja) * | 2018-02-16 | 2021-02-04 | 日本電信電話株式会社 | ハウリング抑圧装置、その方法、およびプログラム |
JP7028307B2 (ja) | 2018-02-16 | 2022-03-02 | 日本電信電話株式会社 | ハウリング抑圧装置、その方法、およびプログラム |
CN118016042A (zh) * | 2024-04-09 | 2024-05-10 | 成都启英泰伦科技有限公司 | 一种啸叫抑制方法及装置 |
CN118016042B (zh) * | 2024-04-09 | 2024-05-31 | 成都启英泰伦科技有限公司 | 一种啸叫抑制方法及装置 |
Also Published As
Publication number | Publication date |
---|---|
US7912230B2 (en) | 2011-03-22 |
CN1951147A (zh) | 2007-04-18 |
CN1951147B (zh) | 2011-08-17 |
US20080021703A1 (en) | 2008-01-24 |
JPWO2005125273A1 (ja) | 2008-04-17 |
JP4675888B2 (ja) | 2011-04-27 |
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