JP7020257B2 - Audio equipment, sound effect factor calculation method, and program - Google Patents

Description

The present invention relates to a technique for supporting sound reproduction in a noisy environment.

Various technologies have been proposed to support sound reproduction so that the reproduced sound is not buried in the noise when reproducing a sound such as a musical sound in a noisy environment such as the passenger compartment of a moving vehicle. Examples thereof include the technique disclosed in Patent Document 1.

In the technique disclosed in Patent Document 1, a microphone is installed in an environment where the reproduced sound is emitted from the speaker, and the reproduced sound and the noise heard in the environment are collected by the microphone. Then, in the technique disclosed in Patent Document 1, the average value of the amplitude spectrum of the noise and the average value of the amplitude spectrum of the reproduced sound are calculated for each frequency band so that the amplitude spectrum of the reproduced sound is not buried in the amplitude spectrum of the noise. In addition, the volume of the reproduced sound is corrected for each frequency band.

Japanese Unexamined Patent Publication No. 11-298990

However, in the conventional technique, when a steep peak appears in the amplitude spectrum of the reproduced sound in a certain frequency band, the volume of the frequency band is determined to be low by averaging the amplitude spectrum of the reproduced sound, and the frequency band is determined. The volume of the reproduced sound is raised throughout. Therefore, although it is sufficient to be able to distinguish the sound corresponding to the peak, there is a problem that the volume of the reproduced sound in the frequency band is excessively raised.

In one aspect of the audio device according to the present invention, a short-time frequency analysis is performed on each signal obtained by dividing a first sound signal representing a reproduced sound radiated from a speaker to the environment into a plurality of signals in the time axis direction for a certain period of time. The first estimation unit that specifies the peak of the amplitude spectrum in each frequency and estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum, and the second that represents the noise heard in the environment. A short-time frequency analysis is performed on each signal obtained by dividing the sound signal into a plurality of signals in the time axis direction, the peak of the amplitude spectrum in the fixed time is specified for each frequency, and the noise is based on the peak of the specified amplitude spectrum. The second estimation unit that estimates the volume of each frequency band, the volume estimated by the first estimation unit, and the volume estimated by the second estimation unit are compared for each frequency band, and based on the comparison result. A calculation unit for calculating an acoustic effect coefficient applied to the first sound signal is provided.

One aspect of the acoustic effect coefficient calculation method according to the present invention is to perform short-time frequency analysis on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction. The peak of the amplitude spectrum in a certain time is specified for each frequency, the volume of the reproduced sound is estimated for each frequency band based on the peak of the specified amplitude spectrum, and the second sound signal representing the noise heard in the environment is expressed. The peak of the amplitude spectrum in the fixed time is specified for each frequency by performing a short-time frequency analysis on each signal obtained by dividing the signal into a plurality of signals in the time axis direction, and the volume of the noise is based on the peak of the specified amplitude spectrum. Is estimated for each frequency band, the volume estimated for the reproduced sound and the volume estimated for the noise are compared for each frequency band, and the acoustic effect coefficient given to the first sound signal is obtained based on the comparison result. calculate.

In the program according to the present invention, the processor performs a short-time frequency analysis on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and at a fixed time. The first estimation unit that specifies the peak of the amplitude spectrum for each frequency and estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum, and the second sound that represents the noise heard in the environment. A short-time frequency analysis is performed on each signal obtained by dividing the signal into a plurality of signals in the time axis direction to identify the peak of the amplitude spectrum for each frequency in the fixed time, and the noise of the noise is based on the peak of the specified amplitude spectrum. The second estimation unit that estimates the volume for each frequency band, the volume estimated by the first estimation unit, and the volume estimated by the second estimation unit are compared for each frequency band, and the above is based on the comparison result. It functions as a calculation unit that calculates the acoustic effect coefficient given to the first sound signal.

It is a figure which shows the structural example of the audio system including the audio apparatus 120 of one Embodiment of this invention. It is a figure which shows the configuration example of an audio apparatus 120. It is a figure which shows an example of the storage contents of the correction table 301. It is a flowchart which shows the flow of the reproduction support processing which the arithmetic unit 220 of an audio apparatus 120 executes according to the reproduction support program 303. It is a figure which shows the flow of the reproduction sound estimation processing executed by the reproduction sound estimation unit 212. It is a figure which shows an example of the amplitude spectrum generated by the reproduction sound estimation unit 212 in the reproduction sound estimation process step SB100. It is a figure which shows an example of the data DA1 generated by the reproduction sound estimation unit 212 in the reproduction sound estimation process step SB110. It is a figure which shows an example of the data DA2 generated by the reproduction sound estimation unit 212 in the reproduction sound estimation process step SB120. It is a figure which shows the flow of the noise estimation processing executed by a noise estimation unit 213. It is a figure which shows an example of the amplitude spectrum generated by the noise estimation unit 213 in the step SB100 of a noise estimation process. It is a figure which shows an example of the data DB 1 generated by the noise estimation unit 213 in the noise estimation process step SB110. It is a figure which shows an example of the data DB 2 generated by the noise estimation unit 213 in the noise estimation process step SC120. It is a figure which shows the flow of the sound effect coefficient calculation process executed by the sound effect coefficient calculation unit 214. It is a figure which shows an example of the data DC1 which has passed the correction process SD100. It is a figure which shows an example of the data DC2 which shows the processing result of the comparison processing SD110. It is a figure which shows the other example of the data DA2 generated by the reproduction sound estimation part 212 in step SB120 of a volume estimation process. It is a figure which shows the other example of the data DB 2 generated by the noise estimation unit 213 in the volume estimation process step SC120.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the drawings, the dimensions and scale of each part may differ from the actual ones. Moreover, the embodiment described below is a suitable specific example of the present invention. For this reason, the present embodiment is provided with various technically preferable limitations. However, the scope of the present invention is not limited to these forms unless it is stated in the following description that the present invention is particularly limited.

<1. Embodiment>
FIG. 1 is a diagram showing a configuration example of an audio system including the audio device 120 according to the embodiment of the present invention. This audio system is a car audio system that is mounted on a vehicle and reproduces musical sounds and the like in the vehicle compartment 1 of the vehicle. As shown in FIG. 1, the audio system includes an audio device 120, speakers 130-1 to 130-4, and a microphone 140. As shown in FIG. 1, the speakers 130-1 to 130-4 and the microphone 140 are connected to the audio device 120 via a signal line such as an audio cable.

As shown in FIG. 1, the speaker 130-1 is provided in the vicinity of the driver's seat 111 of the vehicle in which the audio device 120 is mounted, and the speaker 130-2 is provided in the vicinity of the passenger seat 112 of the vehicle. Specifically, the speaker 130-1 is provided inside the driver's side door with its sound emitting surface facing the inside of the vehicle interior 1. The speaker 130-2 is provided on the passenger seat side door with its sound emitting surface facing the inside of the passenger compartment 1. The speakers 130-3 and 130-4 are provided so as to sandwich the rear row seat 113 of the vehicle. Specifically, the speaker 130-3 is provided on the rear door on the driver's side of the vehicle in a posture in which the sound emitting surface faces the inside of the vehicle interior 1. The speaker 130-4 is provided on the rear door on the passenger seat side of the vehicle in a posture in which the sound emitting surface faces the inside of the vehicle interior 1. In the following, when it is not necessary to distinguish each of the speakers 130-1 to 130-4, it is referred to as "speaker 130". A sound signal of a reproduced sound such as a musical sound is supplied to the speaker 130 from the audio device 120. A sound signal is an analog signal that represents a sound waveform. The speaker 130 emits a sound corresponding to the sound signal supplied from the audio device 120 into the vehicle interior 1.

The microphone 140 is provided, for example, on the dashboard of a vehicle on which the audio device 120 is mounted. The microphone 140 outputs a sound signal representing a waveform of the sound picked up at the installation position to the audio device 120. The sound picked up by the microphone 140 includes a reproduced sound emitted from the speaker 130 into the vehicle interior 1 and noise other than the reproduced sound. Specific examples of the noise picked up by the microphone 140 include road noise generated when the vehicle travels.

FIG. 2 is a diagram showing a configuration example of the audio device 120. As shown in FIG. 2, the audio device 120 includes a playback device 210, a calculation unit 220, a storage unit 230, an A / D converter 240, a D / A converter 250, and an amplifier 260.

The reproduction device 210 outputs the sound data D1 of the reproduction sound radiated from the speaker 130 to the calculation unit 220. Sound data refers to digital data such as a sample sequence obtained by sampling a sound waveform. Specific examples of the playback device 210 include a recording medium reading device such as a CD drive or a receiver such as a car radio. When the reproduction device 210 is a recording medium reading device, the reproduction device 210 reads the sound data D1 from the recording medium and outputs the read sound data D1 to the calculation unit 220.

A microphone 140 is connected to the A / D converter 240 via a signal line. The A / D converter 240 performs analog / digital conversion on the sound signal given from the microphone 140, and gives the sound data D2 which is the conversion result to the calculation unit 220.

The arithmetic unit 220 is a processor, and is composed of, for example, a single or a plurality of chips. The arithmetic unit 220 is composed of, for example, a central processing unit (CPU) including an interface with peripheral devices, an arithmetic unit, registers, and the like. In addition, a part or all of the functions of the arithmetic unit 220 are realized by hardware such as DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array). You may. The arithmetic unit 220 executes various processes in parallel or sequentially.
The arithmetic unit 220 executes the reproduction support program 303 stored in the storage unit 230, and functions as a control center of the audio device 120. The calculation unit 220 operating according to the reproduction support program 303 does not excessively raise the volume of the reproduced sound represented by the sound data D1 given from the reproduced device 210, and the reproduced sound is not buried in noise such as road noise. The reproduction support process is executed, and the sound data DD, which is the result of the process, is output to the D / A converter 250. The details of this reproduction support process will be clarified later.

The D / A converter 250 performs digital / analog conversion on the sound data DD given from the calculation unit 220 to convert it into a sound signal, and outputs this sound signal to the amplifier 260. Each of the speakers 130-1 to 130-4 is connected to the amplifier 260 via a signal line. The amplifier 260 amplifies the signal level of the sound signal given from the D / A converter 250 to a signal level suitable for sound emission from the speaker 130, and outputs the signal level to the speaker 130.

The storage unit 230 includes a volatile storage unit and a non-volatile storage unit, although detailed illustration is omitted in FIG. The volatile storage unit is, for example, a RAM (Random Access Memory). This volatile storage unit is used by the arithmetic unit 220 as a work area when the reproduction support program 303 is executed. The volatile storage unit is also used as a buffer for storing the sound data D2 given by the A / D converter 240 and the sound data D1 given by the reproduction device 210. The non-volatile storage unit is, for example, a hard disk. The correction table 301, the sound effect coefficient table 302, and the reproduction support program 303 are stored in advance in the non-volatile storage unit.

In the correction table 301, for example, data representing the correction amount of the volume of the reproduced sound when comparing the volume of the noise and the volume of the reproduced sound in each of the plurality of frequency bands divided into the bands of 20 Hz to 10000 Hz is stored in advance. ing. In the present embodiment, as the plurality of frequency bands, an octave band having a center frequency of 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz, each having a bandwidth corresponding to one octave, is adopted. There is. In the following, each of the plurality of frequency bands will be distinguished by a band number from 1 to 7. The center frequency of the frequency band of band number = 1 is 63 Hz, and the center frequency of the frequency band of band number = 2 is 125 Hz. The center frequency of the frequency band of band number = 3 is 250 Hz, and the center frequency of the frequency band of band number = 4 is 500 Hz. The center frequency of the frequency band of band number = 5 is 1000 Hz, the center frequency of the frequency band of band number = 6 is 2000 Hz, and the center frequency of the frequency band of band number = 7 is 4000 Hz.

The stored contents of the correction table 301 are determined according to the characteristics of the audio system including the audio device 120. In the present embodiment, as shown in FIG. 3, a correction storing data indicating that the volume is lowered by 5 dB for the band with the band number = 1 and the volume is raised by 2 to 8 dB for each band with the band numbers = 2 to 7. The table 301 is stored in the storage unit 230 in advance.

In the sound effect coefficient table 302, the volume of the reproduced sound is corrected so that the reproduced sound is not buried in the noise by associating the difference between the volume of the reproduced sound corrected according to the stored contents of the correction table 301 and the volume of the noise. Data representing the sound effect coefficient (for example, the amount of increase in volume) to be performed is stored.

The arithmetic unit 220 reads the reproduction support program 303 from the non-volatile storage unit to the volatile storage unit when the power supply of the audio device 120 (not shown in FIG. 2) is turned on, and starts executing the reproduction support program 303. The calculation unit 220 operating according to the reproduction support program 303 executes the reproduction support process (see FIG. 4), and the acoustic effect imparting unit 211, the reproduced sound estimation unit 212, the noise estimation unit 213, and the acoustic effect shown in FIG. It functions as a coefficient calculation unit 214 and an echo canceling unit 215. That is, each of the sound effect imparting unit 211, the reproduced sound estimation unit 212, the noise estimation unit 213, the sound effect coefficient calculation unit 214, and the echo canceling unit 215 in FIG. 2 is a software module realized according to software.

As shown in FIG. 2, sound data D1 is given to each of the sound effect imparting unit 211, the reproduced sound estimation unit 212, the noise estimation unit 213, and the echo canceling unit 215. Further, sound data D2 is also given to the echo canceling unit 215.

The echo canceling unit 215 executes the echo canceling process SA100 in FIG. The echo canceling unit 215 reads the sound data D1'from the above buffer in consideration of the characteristics of the sound propagation path such as the speaker 130, the space where the reproduced sound from the speaker 130 is emitted (vehicle compartment 1), and the microphone 140. It is generated based on the sound data D1. The characteristics of the sound propagation path include, for example, the amplitude characteristics for each frequency and the echo due to reflection. Specifically, the echo canceling unit 215 estimates the coefficient of the FIR (finite impulse response) filter representing the characteristics of the propagation path in real time, and inputs the sound data D1 to the FIR filter in which the estimated coefficient is set. Obtain the sound data D1'. The echo canceling unit 215 excludes the signal component represented by the sound data D1'from the sound data D2, generates new sound data D3, and outputs the new sound data D3 to the noise estimation unit 213.

The reproduced sound estimation unit 212 executes the reproduced sound estimation process SA110 in FIG. FIG. 5 is a diagram showing the flow of the reproduced sound estimation process. As shown in FIG. 5, the reproduced sound estimation unit 212 first reads the sound data D1 for a fixed time from the buffer, divides the sound data D1 into processing unit data for a time shorter than the fixed time, and shortens the time. Frequency analysis is performed and converted into data in the frequency region (step SB100). In the present embodiment, the fixed time is a time corresponding to a plurality of cycles (for example, 4 cycles) of the corresponding sounds of the lowest frequency in the plurality of frequency bands, and the processing unit data corresponds to the one cycle. Sound data for hours. In FIG. 5, short-time frequency analysis is abbreviated as STFT (Short Time Fourier Transform). Further, as a specific algorithm for short-time frequency analysis, FFT (Fast Fourier Transform) can be mentioned. For example, when the sound data D1 for a certain period of time is divided into four processing unit data, the amplitude spectra SP1-1 to SP1-4 shown in FIG. 6 can be obtained by performing a short-time frequency analysis on each processing unit data. can get. In the following, when it is not necessary to distinguish each of the amplitude spectra SP1-1 to SP1-4, it is referred to as “amplitude spectrum SP1”.

In step SB110, the reproduced sound estimation unit 212 identifies the peak (maximum value) of the amplitude spectrum in the fixed time for each frequency from the data in the frequency domain obtained in step SB100, and the amplitude of each frequency in the fixed time. Generate data DA1 representing the peak of the spectrum. For example, when data representing the amplitudes SP1-1 to SP1-4 are obtained in step SB100, the reproduced sound estimation unit 212 generates the data DA1 shown in FIG. 7.

In step SB120, the reproduced sound estimation unit 212 analyzes the data generated in step SB110 to estimate the volume of the reproduced sound in the fixed time for each frequency band, and the data DA2 (see FIG. 8) showing the estimation result. Is output to the sound effect coefficient calculation unit 214. More specifically, the reproduced sound estimation unit 212 determines which frequency has the maximum peak of the amplitude spectrum for each frequency band with reference to the data DA1, and the maximum peak is the reproduced sound in the frequency band. The volume is set to. For example, it is assumed that the peak of the amplitude spectrum of the center frequency is the maximum in the frequency band of band number = 1. In this case, the reproduced sound estimation unit 212 sets the peak of the amplitude spectrum of the center frequency (63 Hz) as the volume of the reproduced sound in the frequency band of band number = 1. In the present embodiment, the volume of the reproduced sound in the fixed time is estimated based on the maximum value of the peak of the amplitude spectrum of each frequency, not the average value of the amplitude spectrum of each frequency belonging to the frequency band for each frequency band. Is to avoid the harmful effects caused by using the average value.

The noise estimation unit 213 executes the noise estimation process A120 in FIG. FIG. 9 is a diagram showing a flow of noise estimation processing. As shown in FIG. 9, the noise estimation unit 213 executes the processing of the above-mentioned steps SB100 and SB110 with the sound data D3 for a certain period of time as the processing target. By executing the process of step SB100 with the sound data D3 as the processing target, for example, SP2-4 is generated from the amplitude spectra SP2-1 shown in FIG. In the following, when it is not necessary to distinguish each of the amplitude spectra SP2-1 to SP2-4, it is referred to as “amplitude spectrum SP2”. Then, the noise estimation unit 213 executes step SB110 with the amplitude spectra SP2-1 to SP2-4 (see FIG. 10) as processing targets, so that data representing the peak of the amplitude spectrum of each frequency of the noise in the fixed time. Generate DB1 (see FIG. 11).

In step SC120, which is executed after step SB110 in the noise estimation process, the noise estimation unit 213 analyzes the data DB1 to estimate the noise volume in the fixed time for each frequency band, and the data showing the estimation result. DB2 (see FIG. 12) is output to the acoustic effect coefficient calculation unit 214. More specifically, in this step SC120, the noise estimation unit 213 determines which frequency has the smallest peak of the amplitude spectrum for each frequency band with reference to the data DB 1, and sets the minimum peak to the frequency. The volume of noise in the band. For example, it is assumed that the peak of the amplitude spectrum of the upper limit frequency is the smallest in the frequency band of band number = 1. In this case, the noise estimation unit 213 uses the peak of the amplitude spectrum of the frequency as the volume of noise in the frequency band. In the present embodiment, the volume of noise in the fixed time is estimated based on the minimum value of the peak of the amplitude spectrum of each frequency, not the average value of the amplitude spectrum of each frequency belonging to the frequency band for each frequency band. This is to prevent the volume of noise from becoming excessive due to the influence of sudden noise, and to avoid the harmful effects caused by using the average value.

In the present embodiment, the volume of noise in the fixed time is estimated for each frequency band based on the minimum value of the peak of the amplitude spectrum of each frequency belonging to the frequency band. However, the volume of noise may be estimated based on the median value of the peak of the amplitude spectrum of each frequency in the frequency band or the most frequent value obtained by making a histogram of the value of the peak of the amplitude spectrum of each frequency. .. This is because it is considered that these modes also prevent the noise volume from becoming excessive due to the influence of sudden noise, and at the same time, avoid the harmful effects caused by using the average value. Further, the average value of the peaks of the amplitude spectrum may be calculated by excluding the maximum value and the minimum value from the peak of the amplitude spectrum of each frequency belonging to the frequency band, and the average value may be used as the volume of noise in the frequency band. Even in such an embodiment, it is possible to avoid being affected by noise having a steep peak as compared with the embodiment in which the average value is calculated without excluding the maximum value and the minimum value.

The sound effect coefficient calculation unit 214 executes the sound effect coefficient calculation process SA130 in FIG. FIG. 13 is a diagram showing the flow of the sound effect coefficient calculation process. In the correction process (SD100) in FIG. 13, the sound effect coefficient calculation unit 214 corrects the volume of each frequency band represented by the data DA2 according to the stored contents (see FIG. 3) of the correction table 301, and corrects the corrected volume. The data DC1 to be represented (see FIG. 14) is generated. For example, the correction table 301 shown in FIG. 3 stores data indicating that the volume of the frequency band of band number = 1 is reduced by 5 dB. Therefore, in the correction process of the present embodiment, the volume of the frequency band of band number = 1 is reduced by 5 dB from the volume of the frequency band indicated by the data DA2.

In the comparison process (FIG. 13: SD110) following the correction process, the sound effect coefficient calculation unit 214 compares the volume of the reproduced sound and the volume of the noise in each of the plurality of frequency bands for each frequency band, and the comparison result is obtained. The data DC2 indicating the above is generated. Specifically, the acoustic effect coefficient calculation unit 214 generates the data DC2 (see FIG. 15) by subtracting the volume indicated by the data DB2 from the volume indicated by the data DC1 for each frequency band. The frequency band in which the volume is a negative value in the data DC2 means that the reproduced sound is buried in noise. For example, the data DC2 shown in FIG. 15 shows that the reproduced sound is buried in noise in each frequency band of band numbers = 1 and 2. Then, in the coefficient calculation process (FIG. 13: SD120), the acoustic effect coefficient calculation unit 214 responds to the difference between the volume of the reproduced sound and the volume of the noise in the frequency band (volume difference indicated by the data DC2) for each frequency band. The sound effect coefficient is read out from the sound effect coefficient table 302 and given to the sound effect imparting unit 211. For example, when the data DC2 shown in FIG. 15 is calculated by the comparison process, an acoustic effect indicating that the volume of the reproduced sound in each frequency band of band numbers = 1 and 2 is raised according to the volume difference indicated by the data DC2. The coefficient is given from the sound effect coefficient calculation unit 214 to the sound effect imparting unit 211.

The sound effect imparting unit 211 imparts an acoustic effect (adjustment of the volume in the present embodiment) according to the acoustic effect coefficient given by the acoustic effect coefficient calculation unit 214 to the sound data D1 given by the reproduction device 210. Then, the sound data to which the sound effect has been added is output to the D / A converter 250.

Due to such a configuration, the sound data given from the audio device 120 of the present embodiment to the speaker 130 is provided with an acoustic effect that prevents the reproduced sound in each frequency band from being buried in the noise in the frequency band. Therefore, the reproduced sound is not buried in the noise in any frequency band.

Further, according to the audio device 120 of the present embodiment, the volume of the reproduced sound in the frequency band in which a steep peak appears in the amplitude spectrum of the reproduced sound is estimated based on the peak. Therefore, the volume of the reproduced sound in the frequency band is estimated to be underestimated, and the volume of the reproduced sound in the frequency band is not excessively increased. Further, even if a steep peak appears in the amplitude spectrum of noise in a certain frequency band, the volume of noise in the frequency band is not overestimated, and the volume of reproduced sound in the frequency band is excessively raised. There is no such thing.

As described above, according to the present embodiment, when the sound is reproduced in an environment where noise is present, it is possible to prevent the reproduced sound from being buried in the noise without raising the volume of the reproduced sound excessively.

<2. Modification example>
The above embodiments can be variously modified. Specific modes of modification are illustrated below. Two or more embodiments arbitrarily selected from the following examples can be appropriately merged as long as they do not conflict with each other.
<2-1: Modification 1>
In the above embodiment, the volume of the reproduced sound and the volume of the noise are estimated in octave band units, and the volume of the reproduced sound is corrected in octave band units. However, the volume of the reproduced sound and the noise may be estimated and the volume of the reproduced sound may be corrected in units of 1/3 octave bands having a bandwidth of 1/3. In this case, if the correction table 301 stores data representing the correction amount of the volume of the reproduced sound when comparing the volume of the noise and the volume of the reproduced sound in each of the frequency bands in units of 1/3 octave. good. Further, in the reproduced sound estimation unit 212, instead of the data D1 shown in FIG. 8, as shown in FIG. 16, the reproduced sound in the frequency band of band numbers = 1 to 21 each having a bandwidth of 1/3 octave is used. The data D1 representing the volume may be generated. Similarly, the noise estimation unit 213 is made to generate data D2 representing the volume of noise in each frequency band of band numbers = 1 to 21 as shown in FIG. 17, instead of the data D2 shown in FIG. Just do it. In FIGS. 16 and 17, the center frequency of the frequency band of band number = 1 is 63 Hz, the center frequency of the frequency band of band number = 2 is 80 Hz, ... The center frequency of the frequency band of band number = 20 is 5000 Hz, and the band. The center frequency of the frequency band of number = 21 is 6300 Hz.

<2-2: Modification 2>
In the above embodiment, the sound effect imparting unit 211, the reproduced sound estimation unit 212, the noise estimation unit 213, the sound effect coefficient calculation unit 214, and the echo canceling unit 215 are realized by software. However, each of the sound effect imparting unit 211, the reproduced sound estimation unit 212, the noise estimation unit 213, the sound effect coefficient calculation unit 214, and the echo canceling unit 215 is realized by hardware such as an electronic circuit, and these hardwares are combined. The audio device 120 may be configured. In this case, regarding the sound effect coefficient calculation unit 214, a correction unit that executes a correction process (FIG. 13: SD100), a comparison unit that executes a comparison process (FIG. 13: SD110), and a coefficient calculation process (FIG. 13; SD120). ) May be realized by an electronic circuit, and each part of the coefficient calculation part may be combined and configured.

<2-3: Modification 3>
In the above embodiment, the correction amount (acoustic effect coefficient) of the volume of the reproduced sound is determined so that the reproduced sound is not buried in the noise. However, the data indicating the volume of the reproduced sound after correction is stored in the buffer, and whether or not it is the attack part of the sound or the release part from the time change of the volume of the reproduced sound indicated by the stored contents of the buffer. It may be determined whether or not, and the correction amount may be adjusted according to the determination result. For example, in the case of the attack unit, it is preferable to adjust the correction amount so that the volume of the reproduced sound after the correction exceeds the volume of the reproduced sound after the previous correction. This is because if the volume of the reproduced sound after the correction is lower than the volume of the reproduced sound after the previous correction, the attack feeling is diminished. Similarly, in the case of the release unit, it is preferable to adjust the correction amount so that the volume of the re-sound after the correction is lower than the volume of the reproduced sound after the previous correction. This is because if the volume of the reproduced sound after the correction exceeds the volume of the reproduced sound after the previous correction, the feeling of release is diminished.

<2-4: Modification 4>
Although the audio device 120 of the above embodiment includes the playback device 210, the playback device 210 may be connected to the audio device 120 via a signal line. That is, the reproduction device 210 is not an essential component of the audio device of the present invention and can be omitted. Similarly, the storage unit 230 is not an essential component of the audio device of the present invention and can be omitted. When the storage unit 230 is omitted, the storage unit 230 plays a role in a hard disk drive connected to the audio device 120 via a USB cable or the like, or a hard disk drive accessible by the arithmetic unit 220 via a telecommunication line such as the Internet. You just have to carry.

If the microphone 140 includes an A / D converter, the A / D converter 240 is unnecessary, and if the speaker 130 or the amplifier 260 includes a D / A converter, the D / A converter is unnecessary. 250 is unnecessary. Further, the amplifier connected to the audio device 120 via the signal line may play the role of the amplifier 260, and in this case, the amplifier 260 can be omitted.

Further, when a microphone having sharp directivity is used as the microphone 140 and the microphone is installed near a sound source of noise so that the difference tone radiated from the speaker 130 cannot be picked up by the microphone 140. , The echo canceling unit 215 may be omitted. Further, when the sound effect imparting unit 211 is realized by a DSP different from the audio device 120, the sound effect imparting unit 211 can also be omitted.

That is, in the audio device of the present invention, a short-time frequency analysis is performed on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of sounds in the time axis direction, and the amplitude in a certain time is set. The first estimation unit (reproduced sound estimation unit 212 in the above embodiment) that specifies the peak of the spectrum for each frequency and estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum, and the environment. A short-time frequency analysis was performed on each signal obtained by dividing the second sound signal representing the noise heard in the above into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in the fixed time was specified and specified for each frequency. The second estimation unit (noise estimation unit 213 in the above embodiment) that estimates the volume of the noise for each frequency band based on the peak of the amplitude spectrum, the volume estimated by the first estimation unit, and the second estimation unit. The volume estimated by is compared for each frequency band, and the acoustic effect coefficient given to the first sound signal so that the volume of the reproduced sound exceeds the volume of the noise in each frequency band is calculated based on the comparison result. It suffices to include a calculation unit (acoustic effect coefficient calculation unit 214 in the above embodiment).

<2-5: Modification 5>
In the above embodiment, the correction table 301 and the sound effect coefficient table 302 are stored in the storage unit 230 separately from the reproduction support program 303, but the correction table 301 and the sound effect coefficient table 302 are stored in the reproduction support program 303. It may be embedded in. Further, in the above embodiment, the reproduction support program 303 is stored in advance in the storage unit 230 of the audio device 120, but the reproduction support is performed regardless of whether or not the correction table 301 and the sound effect coefficient table 302 are embedded. The program 303 may be provided alone. As a specific mode of providing the reproduction support program 303, a mode of writing and distributing it on a computer-readable recording medium such as a CD-ROM, or a mode of distributing it by downloading via a telecommunication line such as the Internet can be considered. By installing the reproduction support program 303 distributed in the above manner on a general computer device such as a personal computer and causing the processor of the computer device to execute the reproduction support program 303, the computer device of the above embodiment can be obtained. It becomes possible to function as an audio device 120. In the case where the correction table 301 and the sound effect coefficient table 302 are not embedded in the reproduction support program 303, these tables are stored in an accessible storage device of the computer device that executes the reproduction support program 303. good.

<2-6: Modification 6>
In the above embodiment, an example of application of the present invention to an audio device included in a car audio system has been described, but the application target of the present invention is not limited to the audio device included in the car audio system. Further, in the above embodiment, the acoustic effect coefficient given to the first sound signal so that the volume of the reproduced sound exceeds the volume of the noise in each frequency band is set so that the reproduced sound is not buried in the noise in each frequency band. Calculated. However, the calculation of the sound effect coefficient given to the sound signal of the reproduced sound (that is, tuning of the reproduced sound) may be performed according to the comparison result between the volume estimated for the reproduced sound and the volume estimated for the noise. .. In short, if it is an audio device that reproduces sound in a noisy environment, by applying the present invention, tuning of the reproduced sound can be performed while avoiding that the volume of the reproduced sound is underestimated. Will be possible.

<3. Aspects grasped from at least one of the embodiments and each modification>
The following aspects are grasped from at least one of each of the above-described embodiments and modifications.
One aspect of the audio device is to perform short-time frequency analysis on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and to obtain an amplitude spectrum at a fixed time. The first estimation unit that specifies the peak for each frequency and estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum, and the second sound signal that represents the noise heard in the environment are timed. A short-time frequency analysis is performed on each signal obtained by dividing into a plurality of signals in the axial direction to identify the peak of the amplitude spectrum for each frequency, and the volume of the noise is determined based on the peak of the specified amplitude spectrum. The second estimation unit estimated for each band, the volume estimated by the first estimation unit, and the volume estimated by the second estimation unit are compared for each frequency band, and the first sound is based on the comparison result. It is provided with a calculation unit for calculating an acoustic effect coefficient applied to a signal.
According to this aspect, the volume of the reproduced sound in each frequency band is estimated according to the peak of the amplitude spectrum of each frequency belonging to the frequency band. Therefore, even when a steep peak appears in the amplitude spectrum of the reproduced sound as compared with the conventional technique of estimating the volume of the reproduced sound according to the average value of the amplitude spectrum of each frequency belonging to the frequency band. , It is avoided that the volume of the reproduced sound in the frequency band to which the frequency corresponding to the peak belongs is underestimated. According to this aspect, even when a steep peak appears in the amplitude spectrum of the reproduced sound reproduced in a noisy environment, the volume of the reproduced sound in the frequency band to which the frequency corresponding to the peak belongs is It is possible to tune the reproduced sound while avoiding underestimation.

In one aspect of the audio apparatus described above, it is preferable that the first estimation unit estimates the volume of the reproduced sound in the frequency band based on the maximum value of the peak of the amplitude spectrum of each frequency belonging to the frequency band.
When a steep peak appears in the amplitude spectrum of the reproduced sound, the peak corresponds to the above maximum value. Therefore, according to this aspect, it is possible to surely prevent the volume of the reproduced sound in the frequency band from being underestimated.

In one aspect of the audio apparatus described above, the second estimation unit sets the volume of the noise in the frequency band to the minimum value, the median value, the most frequent value or each frequency of the peak of the amplitude spectrum of each frequency belonging to the frequency band. It is preferable to estimate based on one of the average values calculated by excluding the minimum value and the maximum value from the peak of the corresponding amplitude spectrum.
According to this aspect, when a steep peak appears in the amplitude spectrum of the reproduced sound, the peak corresponds to the above maximum value. According to this aspect, since the maximum value is not used for the volume of noise in each frequency band, the volume of the noise in the frequency band in which a steep peak appears in the amplitude spectrum of the noise is overestimated. Can be reliably avoided.

In one aspect of the audio device described above, the calculation unit compares the volume estimated by the first estimation unit and the volume estimated by the second estimation unit for each frequency band, and each is based on the comparison result. It is characterized in that an acoustic effect coefficient given to the first sound signal is calculated so that the volume of the reproduced sound exceeds the volume of the noise in the frequency band.
According to this aspect, when the sound is reproduced in the environment where the sound is present, it is possible to tune the reproduced sound so as not to be buried in the noise without raising the volume of the reproduced sound excessively.

In one aspect of the audio device, the second sound signal is generated by excluding the signal component corresponding to the first sound signal from the third sound signal output from the microphone that collects the reproduced sound and the noise. It is preferable to do.
According to this aspect, it becomes possible to easily and accurately estimate the volume of noise by using the output signal of the microphone.

In one aspect of the audio device, the calculation unit defines a correction amount for the volume of the reproduced sound in each frequency band estimated by the first estimation unit for each frequency band, and according to the correction table, the first unit. 1 A correction unit that corrects the volume of the reproduced sound estimated by the estimation unit for each frequency band, a volume after correction by the correction unit, and a volume of the noise estimated by the second estimation unit for each frequency band. It is preferable to have a comparison unit to be compared with, and to calculate the sound effect coefficient for each frequency band according to the comparison result in the comparison unit.
According to this aspect, it becomes possible to correspond to various audio systems by switching the correction table.

One aspect of the acoustic effect coefficient calculation method is to perform short-time frequency analysis on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and for a certain period of time. The peak of the amplitude spectrum is specified for each frequency, the volume of the reproduced sound is estimated for each frequency band based on the peak of the specified amplitude spectrum, and the second sound signal representing the noise heard in the environment is measured in the time axis direction. Short-time frequency analysis is performed on each signal obtained by dividing into a plurality of signals to identify the peak of the amplitude spectrum for each frequency, and the volume of the noise is determined for each frequency band based on the peak of the specified amplitude spectrum. The volume estimated for the reproduced sound and the volume estimated for the noise are compared for each frequency band, and the acoustic effect coefficient given to the first sound signal is calculated based on the comparison result.
Also in this embodiment, even if a steep peak appears in the amplitude spectrum of the reproduced sound reproduced in a noisy environment, the volume of the reproduced sound in the frequency band to which the frequency corresponding to the peak belongs is too low. It is possible to tune the reproduced sound while avoiding the estimation.

One aspect of the program is that the processor performs a short-time frequency analysis on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of sounds in the time axis direction, and the amplitude at a fixed time. The first estimation unit that specifies the peak of the spectrum for each frequency and estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum, and the second sound signal that represents the noise heard in the environment. The peak of the amplitude spectrum in the fixed time is specified for each frequency by performing a short-time frequency analysis on each signal obtained by dividing the signal into a plurality of parts in the time axis direction, and the volume of the noise is based on the peak of the specified amplitude spectrum. The second estimation unit that estimates for each frequency band, the volume estimated by the first estimation unit, and the volume estimated by the second estimation unit are compared for each frequency band, and the second estimation unit is based on the comparison result. It functions as a calculation unit that calculates the acoustic effect coefficient given to one sound signal.
Also in this embodiment, even if a steep peak appears in the amplitude spectrum of the reproduced sound reproduced in a noisy environment, the volume of the reproduced sound in the frequency band to which the frequency corresponding to the peak belongs is too low. It is possible to tune the reproduced sound while avoiding the estimation.

1 ... Car room, 111 ... Driver's seat, 112 ... Passenger seat, 113 ... Back row seat, 120 ... Audio device, 130,130-1. 130-2. 130-3. 130-4 ... Speaker, 140 ... Microphone, 210 ... reproduction device, 220 ... arithmetic unit, 230 ... storage unit, 240 ... A / D converter, 250 ... D / A converter, 260 ... amplifier, 211 ... acoustic effect addition unit, 212 ... reproduction sound estimation unit, 213 ... Noise estimation unit, 214 ... Acoustic effect coefficient calculation unit, 215 ... Echo canceling unit, 301 ... Correction table, 302 ... Acoustic effect coefficient table, 303 ... Playback support program.

Claims (8)

A short-time frequency analysis is performed on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in a certain time is specified for each frequency. The first estimation unit that estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum,
A short-time frequency analysis is performed on each signal obtained by dividing the second sound signal representing the noise heard in the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in the fixed time is specified for each frequency. A second estimation unit that estimates the volume of the noise for each frequency band based on the peak of the specified amplitude spectrum, and
Calculation to compare the volume estimated by the first estimation unit and the volume estimated by the second estimation unit for each frequency band, and calculate the acoustic effect coefficient given to the first sound signal based on the comparison result. Department and
An audio device equipped with. The audio device according to claim 1, wherein the first estimation unit estimates the volume of the reproduced sound in a frequency band based on the maximum value of the peak of the amplitude spectrum of each frequency belonging to the frequency band. The second estimation unit sets the volume of the noise in the frequency band from the minimum value, the median value, the most frequent value of the peak value of the amplitude spectrum of each frequency belonging to the frequency band, or the peak value of the amplitude spectrum corresponding to each frequency. The audio device according to claim 1 or 2, wherein the estimation is based on any of the average values calculated excluding the maximum value and the maximum value. The calculation unit compares the volume estimated by the first estimation unit and the volume estimated by the second estimation unit for each frequency band, and the volume of the reproduced sound in each frequency band is based on the comparison result. The audio device according to any one of claims 1 to 3, wherein an acoustic effect coefficient applied to the first sound signal is calculated so as to exceed the volume of the noise. Having an echo canceling unit that generates the second sound signal by excluding the signal component corresponding to the first sound signal from the third sound signal output from the microphone that collects the reproduced sound and the noise. The audio device according to any one of claims 1 to 4, wherein the audio device is characterized. The calculation unit
The correction amount for the volume of the reproduced sound in each frequency band estimated by the first estimation unit is specified for each frequency band, and the volume of the reproduced sound estimated by the first estimation unit is calculated according to the correction table. A correction unit that corrects for each frequency band,
It has a comparison unit for comparing the volume corrected by the correction unit and the volume of the noise estimated by the second estimation unit for each frequency band.
The audio device according to any one of claims 1 to 5, wherein the acoustic effect coefficient is calculated for each frequency band according to the comparison result in the comparison unit. A short-time frequency analysis is performed on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in a certain time is specified for each frequency. , The volume of the reproduced sound is estimated for each frequency band based on the peak of the specified amplitude spectrum, and
A short-time frequency analysis is performed on each signal obtained by dividing the second sound signal representing the noise heard in the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in the fixed time is specified for each frequency. The volume of the noise is estimated for each frequency band based on the peak of the specified amplitude spectrum, and the volume of the noise is estimated for each frequency band.
The volume estimated for the reproduced sound and the volume estimated for the noise are compared for each frequency band, and the acoustic effect coefficient given to the first sound signal is calculated based on the comparison result.
Sound effect coefficient calculation method. Processor,
A short-time frequency analysis is performed on each signal obtained by dividing the first sound signal representing the reproduced sound radiated from the speaker to the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in a certain time is specified for each frequency. The first estimation unit that estimates the volume of the reproduced sound for each frequency band based on the peak of the specified amplitude spectrum,
A short-time frequency analysis is performed on each signal obtained by dividing the second sound signal representing the noise heard in the environment into a plurality of signals in the time axis direction, and the peak of the amplitude spectrum in the fixed time is specified for each frequency. A second estimation unit that estimates the volume of the noise for each frequency band based on the peak of the specified amplitude spectrum, and
Calculation to compare the volume estimated by the first estimation unit and the volume estimated by the second estimation unit for each frequency band, and calculate the acoustic effect coefficient given to the first sound signal based on the comparison result. Department and
A program that makes it work.

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