JP2013106197A - Sound quality controller, sound quality control method, and sound quality control program - Google Patents

Abstract

Provided are a sound quality control device, a sound quality control method, and a sound quality control program capable of performing an appropriate sound quality control process in consideration of the background noise level at the time of listening to the reproduced sound on an audio signal. To do.
According to an embodiment, a sound quality control device includes a generation unit, an estimation unit, and a control unit. The generating means generates a first correction gain for masking correction for the environmental sound with respect to the input audio signal. The estimation means estimates the background noise level from the environmental sound. The control means controls the sound quality of the input audio signal based on the first correction gain generated by the generation means and the second correction gain generated according to the background noise level estimated by the estimation means. Apply processing.
[Selection] Figure 3

Description

  Embodiments described herein relate generally to a sound quality control apparatus, a sound quality control method, and a sound quality control program that adaptively perform sound quality control processing on a reproduced audio (audible frequency) signal.

  As is well known, for example, in a broadcast receiving apparatus that receives a television broadcast or an information reproducing device that reproduces recorded information from an information recording medium, the received broadcast signal, a signal read from the information recording medium, or the like When the audio signal is reproduced, the audio signal is subjected to sound quality control processing to further improve the sound quality.

  In this case, at present, for example, when viewing a television broadcast program or the like by a broadcast receiver, the reproduced audio of the program content is added to the reproduced audio signal so that the ambient sound (background noise) is not easily heard. On the other hand, a technique for performing an adaptive sound quality control process according to the surrounding environmental sound has also been proposed.

  By the way, the ambient environmental sound is not limited to clear noise (for example, driving sound of a vacuum cleaner, running water around the kitchen water, outdoor noise, etc.) having a level that most people feel is actually annoying. Reproduced sound may be adversely affected by so-called background noise that is relatively small and steady, excluding such distinct noise.

JP 2010-154388 A

  To provide a sound quality control device, a sound quality control method, and a sound quality control program capable of performing an appropriate sound quality control process in consideration of the ambient background noise level at the time of listening to the reproduced sound for an audio signal. Objective.

  According to the embodiment, the sound quality control device includes a generation unit, an estimation unit, and a control unit. The generating means generates a first correction gain for masking correction for the environmental sound with respect to the input audio signal. The estimation means estimates the background noise level from the environmental sound. The control means controls the sound quality of the input audio signal based on the first correction gain generated by the generation means and the second correction gain generated according to the background noise level estimated by the estimation means. Apply processing.

FIG. 2 is an external view illustrating an example of a digital television broadcast receiving device in an embodiment. The block block diagram shown in order to demonstrate roughly an example of the signal processing system of the digital television broadcast receiver in the embodiment. The block block diagram shown in order to demonstrate an example of the sound quality control processing part with which the digital television broadcast receiver in the same embodiment is provided. The figure shown in order to demonstrate an example of the processing operation which the masking correction gain calculation part which comprises the sound quality control process part in the embodiment performs. The flowchart shown in order to demonstrate a part of example of main processing operation which the background noise estimation part which comprises the sound quality control processing part in the embodiment performs. The flowchart shown in order to demonstrate the other part of an example of main processing operation which the background noise estimation part which comprises the sound quality control processing part in the embodiment performs. The flowchart shown in order to demonstrate the remainder of an example of main processing operation which the background noise estimation part which comprises the sound quality control process part in the embodiment performs. The flowchart shown in order to demonstrate an example of main processing operation which the correction characteristic control part which comprises the sound quality control processing part in the embodiment performs. The characteristic view shown in order to demonstrate an example of main processing operations which the correction characteristic control part in the embodiment performs.

  Hereinafter, embodiments will be described in detail with reference to the drawings. FIG. 1 shows the appearance of a digital television broadcast receiver 11 described in this embodiment. The digital television broadcast receiver 11 includes a thin cabinet 12 and a support base 13 that supports the cabinet 12.

  The cabinet 12 is provided with a video display panel 14 serving as a video display unit at the front center. The cabinet 12 is provided with a microphone 15 at the center of the upper surface thereof, so that environmental sounds around the digital television broadcast receiver 11 can be collected.

  Further, the cabinet 12 is provided with speakers 16 and 16 at both ends at the front lower side. Further, the cabinet 12 is provided with an operation unit 17 including a main power switch 17a and a light receiving unit 19 for receiving operation information transmitted from the remote controller 18 at the lower front portion thereof.

  The support base 13 is pivotally connected to the central portion of the bottom surface of the cabinet 12 so that the cabinet 12 is supported upright while being placed on a predetermined horizontal plane (not shown). It is configured.

  FIG. 2 schematically shows a signal processing system of the digital television broadcast receiver 11. That is, the digital television broadcast signal received by the antenna 20 is supplied to the tuner unit 22 via the input terminal 21, so that a broadcast signal of a desired channel is selected.

  The broadcast signal selected by the tuner unit 22 is supplied to the demodulation / decoding unit 23, restored to a digital video signal, an audio signal, and the like, and then output to the signal processing unit 24. The signal processing unit 24 performs predetermined digital signal processing on the digital video signal and audio signal supplied from the demodulation / decoding unit 23.

  The signal processing unit 24 outputs a digital video signal to the synthesis processing unit 25 and outputs a digital audio signal to the audio processing unit 26. Among these, the composition processing unit 25 superimposes and outputs an OSD (on screen display) signal on the digital video signal supplied from the signal processing unit 24.

  The digital video signal output from the synthesis processing unit 25 is supplied to the video processing unit 27. The video processing unit 27 converts the input digital video signal into an analog video signal in a format that can be displayed on the video display panel 14 in the subsequent stage. The analog video signal is supplied to the video display panel 14 and used for video display.

  The audio processing unit 26 converts the input digital audio signal into an analog audio signal in a format that can be reproduced by the speakers 16 and 16. The analog audio signal is supplied to speakers 16 and 16 for audio reproduction.

  In this case, as will be described in detail later, the audio processing unit 26 uses a signal corresponding to the ambient environmental sound collected by the microphone 15, so that the digital audio signal supplied from the signal processing unit 24 is processed. Appropriate sound quality control processing is performed in consideration of the surrounding background noise level when listening to the reproduced sound.

  Here, in the digital television broadcast receiving apparatus 11, various operations including the above-described various receiving operations are comprehensively controlled by the control unit 28. The control unit 28 incorporates a CPU (central processing unit) 28 a and receives operation information from the operation unit 17 or operation information transmitted from the remote controller 18 and received by the light receiving unit 19. Each unit is controlled so that the operation content is reflected.

  In this case, the control unit 28 uses the memory unit 28b. The memory unit 28b mainly includes a ROM (read only memory) storing a control program executed by the CPU 28a, a RAM (random access memory) for providing a work area to the CPU 28a, and various setting information and control information. And so on.

  Further, an HDD (hard disk drive) 29 is connected to the control unit 28. The control unit 28 encrypts the digital video signal and audio signal obtained from the demodulation / decoding unit 23 by the recording / playback processing unit 30 based on the operation of the operation unit 17 or the remote controller 18 by the user, and a predetermined recording format. After being converted to, it can be controlled to be supplied to the HDD 29 and recorded on the hard disk 29a.

  Further, the control unit 28 causes the HDD 29 to read out digital video signals and audio signals from the hard disk 29 a based on the operation of the operation unit 17 and the remote controller 18 by the user, and decodes them by the recording / playback processing unit 30. Thereafter, by supplying the signal to the signal processing unit 24, it can be controlled to be used for the video display and the audio reproduction described above.

  The digital television broadcast receiver 11 is provided with an input terminal 31 for directly inputting digital video signals and audio signals from the outside. The digital video signal and audio signal input through the input terminal 31 are supplied to the signal processing unit 24 through the recording / playback processing unit 30 based on the control of the control unit 28, and thereafter. It is used for the video display and audio playback described above.

  Further, the digital video signal and audio signal input through the input terminal 31 are recorded and reproduced on the hard disk 29 a by the HDD 29 after being passed through the recording and reproduction processing unit 30 based on the control of the control unit 28. To be served.

  A network interface 32 is connected to the control unit 28. The network interface 32 is connected to an external network line 33. The network line 33 is connected to a network server 34 for providing various services using a communication function via the network line network 33.

  Therefore, the control unit 28 can access the network server 34 and perform information communication via the network interface 32 and the network line network 33 based on the operation of the operation unit 17 and the remote controller 18 by the user. You can use the services you provide.

  FIG. 3 shows an example of a sound quality control processing unit 35 for performing sound quality control processing on the audio signal in the audio processing unit 26. In the sound quality control processing unit 35, the digital audio signal output from the signal processing unit 24 is supplied to the input terminal 36.

  Then, the audio signal supplied to the input terminal 36 is supplied to the equalizer control unit 37 and subjected to the equalizer control processing, and then taken out from the output terminal 38 and used for audio reproduction by the speakers 16 and 16.

  In this case, the equalizer control unit 37 performs a process of correcting the frequency characteristic of the input audio signal based on the correction gain characteristic notified from the correction characteristic control unit 39.

  On the other hand, in the sound quality control processing unit 35, the audio signal supplied to the input terminal 36 is supplied to the reproduction sound analysis unit 40. The reproduction sound analysis unit 40 cuts the input audio signal into frames of about several tens of msec, calculates the signal power Pply of the audio signal in units of frames, and performs a time-frequency conversion process such as DFT (digital fourier transform). , Power spectrum information Sply [k] (k is a frequency index) is calculated and output to the masking correction gain calculation unit 41.

  In addition, the sound quality control processing unit 35 includes an input terminal 42 to which a signal corresponding to ambient environmental sound collected by the microphone 15 is supplied. However, the signal supplied to the input terminal 42 is a signal that suppresses the wraparound of the reproduced sound of the audio signal using an echo canceller or the like from the signal corresponding to the ambient environmental sound collected by the microphone 15. .

  The signal supplied to the input terminal 42 is supplied to the environmental sound analysis unit 43 and the background noise estimation unit 44, respectively. Among these, the environmental sound analysis unit 43 divides the input environmental sound signal into frames of about several tens of msec, similarly to the reproduction sound analysis unit 40. Then, the signal power Penv for each frame is calculated, and the noise masking level is calculated based on the auditory frequency masking characteristic. The calculation of the noise masking level is realized by superimposing frequency masking characteristics based on the power for each frequency band on the frequency components of the entire band from the frequency spectrum obtained by time-frequency converting the environmental sound signal.

  The noise masking level calculated by the environmental sound analysis unit 43 is supplied to the masking correction gain calculation unit 41. As shown in FIG. 4, the masking correction gain calculation unit 41 has a frequency characteristic (power spectrum) of the audio signal calculated by the reproduction sound analysis unit 40 equal to or lower than the noise masking level calculated by the environmental sound analysis unit 43. As shown by the arrows in the figure, the gain coefficient for raising the noise masking level or higher is used as a correction gain value for each frequency band so that the signal component is buried in noise and difficult to hear. Calculated.

  However, excessive gain correction and sudden gain changes in time series cause a sense of incongruity in the sense of hearing, so the gain coefficient should be set with the power Pply of the playback sound of the audio signal and the power Penv of the environmental sound aligned. A value obtained by correcting the gain coefficient by clipping or time smoothing is calculated for each frequency band as a correction gain value Gm [k]. Here, k is an index indicating a frequency band.

  The background noise estimation unit 44 is not an environmental sound that is clearly felt as noise (for example, a driving sound of a vacuum cleaner, running water around a kitchen water, outdoor noise, etc.) during audio reproduction, but is relatively small and steady. Is estimated as the background noise level Pbgn, and the estimated background noise level Pbgn is output.

  Then, the correction characteristic control unit 39 generates a volume correction gain generated based on the correction gain value Gm [k] supplied from the masking correction gain calculation unit 41 and the background noise level Pbgn supplied from the background noise estimation unit 44. Based on Gv, a correction gain characteristic to be notified to the equalizer control unit 37 is generated.

  FIG. 5 to FIG. 7 show a flowchart summarizing an example of the processing operation in which the background noise estimation unit 44 estimates the ambient background noise level Pbgn. Here, background noise is an environmental sound that is relatively small and steadily generated, and a signal component of a clear environmental sound (for example, driving sound of a vacuum cleaner, running water around a kitchen water, outdoor noise, etc.). This means that the signal level is excluded.

  That is, when the processing is started (step S11), the background noise estimation unit 44 transmits a signal corresponding to the environmental sound collected by the microphone 15 in a frame of about several tens of msec in step S12, similarly to the environmental sound analysis unit 43. And the signal power Pfr of each frame is calculated. In this case, as described above, the signal supplied to the background noise estimation unit 44 suppresses the wraparound of the reproduced sound of the audio signal using an echo canceller or the like from the signal corresponding to the environmental sound collected by the microphone 15. It is a thing. As the signal power Pfr, the signal power Penv calculated by the environmental sound analysis unit 43 can be used.

  Thereafter, in step S13, the background noise estimation unit 44 calculates the signal power Pfr of the past frame for the short-term analysis interval in order to calculate the background noise level Psh in the short-term analysis interval of, for example, several seconds used in the subsequent step. While saving, the signal power value of the latest frame is updated.

  In step S14, the background noise estimation unit 44 sets the background noise level prevPbgn calculated last time as the provisional background noise level Pbgn. However, if there is no background noise level prevPbgn calculated last time, the background noise level Pbgn obtained empirically is set as an initial value.

  Next, in step S15, the background noise estimation unit 44 determines whether or not it is a short-term analysis cycle (about several seconds) from the number of frame processing, and if it is determined that it is not a short-term cycle timing (NO), in particular. In step S27, the background noise level Pbgn is not updated, clipping is performed with the upper limit value TH_BGN_max, and the process ends (step S28).

  If it is determined in step S15 that the timing is a short-term cycle (YES), the background noise estimation unit 44 determines in step S16 the signal power Pfr [i] ( i is the median value of the frame period index) and is calculated as the short-term background noise level Psh. In this way, by using the median value, a value close to an audible impression can be obtained as the short-term background noise level Psh compared to the case of using the minimum value.

  Further, the background noise estimation unit 44 stores the short-term background noise level Psh for the long-term analysis section in step S17 in order to use the short-term background noise level Psh in a long-term analysis of, for example, several tens of seconds in the subsequent step. In addition, the latest short-term background noise level is updated.

  Thereafter, the background noise estimation unit 44 compares the calculated short-term background noise level Psh with the previous background noise level prevPbgn in step S18, and if the short-term background noise level Psh is determined to be smaller (YES), In step S19, a smoothed background noise level Pbgn is calculated by taking a weighted average of the calculated short-term background noise level Psh and the previous background noise level prevPbgn by the following equation. Α is a fixed value of 0 <α <1.

Pbgn = α × Psh + (1-α) × prevPbgn
Then, in step S20, the background noise estimation unit 44 updates the previous background noise level prevPbgn to the background noise level Pbgn calculated by the above equation, and the value of the long-term analysis section counter that is a frame counter used in the long-term analysis. Reset Clg. The value Clg of the long-term analysis section counter is a counter value for determining a long-term background noise level increase described later, and is set to zero.

  If it is determined in step S18 that the short-term background noise level Psh is higher (NO), there is a possibility that the background noise level Pbgn increases or an explicit environmental sound is generated. In the former case, there is a continuous increase in the short-term background noise level Psh, and in the latter case, there is a tendency to see an intermittent change in the signal power Pfr.

  Therefore, in order to identify both, the background noise level Pbgn is estimated based on the past short-term background noise level Psh [j] (j is a short-term analysis cycle index) in the long-term analysis section (several tens of seconds). However, this long-term analysis interval may be constant, but long-term analysis slows the background noise level Pbgn update and impairs control tracking. Can be improved.

  That is, it is considered that the environmental sound signal has a higher possibility of background noise as it is closer to general noise characteristics. For this reason, the background noise estimation part 44 shortens the determination area of long-term analysis based on the noise property (similarity) of a signal by step S21. The determination of noise is made based on one or both of the spectral flatness and the spectral fluctuation amount, which are characteristic parameters generated from the frequency spectrum obtained by the environmental sound analysis unit 43.

  In general, stationary noise has a high spectral flatness and a small amount of spectral fluctuation. Based on these characteristic parameters, the noise flatness is high when the spectral flatness is equal to or higher than the threshold or the spectral fluctuation is equal to or lower than the threshold. Judging. Then, in order to determine whether or not the short-term background noise level Psh [j] continuously increases, the background noise level increase duration threshold value Tlng, which is a threshold time to be compared with the value Clg of the long-term analysis interval counter To shorten.

  Next, in step S22, the background noise estimation unit 44 compares the value Clg of the long-term analysis section counter with the background noise level increase duration threshold value Tlng, and the value Clg of the long-term analysis section counter is the background noise level increase duration threshold value. If it is determined that the background noise level is greater than Tlng (YES), it is determined that the background noise level Pbgn is continuously increasing, and the past noise level obtained until the background noise level increase duration threshold value Tlng is reached in step S23. The minimum value of the short-term background noise level Psh [j] is calculated as the long-term background noise level Plg.

  Then, in step S24, the background noise estimation unit 44 calculates a background noise level Pbgn that has been smoothed by taking a weighted average of the calculated long-term background noise level Plg and the previous background noise level prevPbgn according to the following equation. Β is a fixed value of 0 <β <1.

Pbgn = β × Plg + (1-β) × prevPbgn
Thereafter, in step S25, the background noise estimation unit 44 updates the previous background noise level prevPbgn to the background noise level Pbgn calculated by the above equation, and sets the long-term analysis section counter value Clg as the long-term background noise level Plg. Set to the elapsed time (counter value) up to now based on the time of the adopted short-term analysis interval.

  Then, after step S20 or S25, or when it is determined in step S22 that the value Clg of the long-term analysis section counter is equal to or less than the background noise level increase duration threshold value Tlng (NO), the background noise estimation unit 44 In step S26, the value Clg of the long-term analysis section counter is incremented by 1 for each short-term analysis cycle timing.

  Thereafter, the background noise estimation unit 44 clips the background noise level Pbgn with the upper limit value TH_BGN_max in step S27, and ends the process (step S28). This clipping process is used to suppress the background noise level below the expected background noise level so that the background noise level Pbgn does not become excessively high in the situation where explicit environmental sounds are continuously generated even in long-term analysis. belongs to. The background noise level Pbgn is calculated by the background noise estimation unit 44 as described above.

  FIG. 8 shows a flow chart summarizing the processing operation for generating the correction gain characteristic notified from the correction characteristic control unit 39 to the equalizer control unit 37. That is, the correction characteristics of the equalizer control unit 37 include a correction gain characteristic Gm [k] based on the masking correction gain calculation unit 41 and a gain correction (equivalent to the sound volume) Gv over the entire band.

  This is because if the power discrepancy between the playback sound and the environmental sound is large, the difference between the original sound characteristics becomes too large due to noise masking correction, which may lead to a sense of incongruity. This is because the noise masking correction gain described with reference to FIG. 4 is calculated in a state where the values are aligned, and the correction intensity is controlled according to the level of the environmental sound in the gain correction over the entire band. Hereinafter, calculation of the correction gain Gv over the entire band will be described.

  First, when the process is started (step S29), the correction characteristic control unit 39, in step S30, is the power of the environmental sound signal in units of a frame of about several tens of msec, like the environmental sound analysis unit 43 and the background noise estimation unit 44. To obtain the environmental sound level Penv. This indicates the power of the entire environmental sound without any distinction between explicit environmental sound and background noise.

  Next, in step S31, the correction characteristic control unit 39 calculates a standard volume correction gain Gst according to the environmental sound level Penv. This is determined in accordance with the relationship between the environmental sound level and the volume correction gain, as indicated by the bold line in FIG. That is, when the environmental sound level is equal to or lower than the specified value TH_BGN_max, the sound volume is not corrected. This is because if the correction sound fluctuates due to slight fluctuations in the environmental sound signal, it will lead to a sense of incongruity. Further, an upper limit GAIN_max is set so that the correction gain value does not become too large.

  Thereafter, the correction characteristic control unit 39 compares the background noise level Pbgn with the minimum background noise level TH_BGN_min in step S32, and if it is determined that the background noise level Pbgn is smaller than the minimum background noise level TH_BGN_min (YES), step In S33, the standard volume correction gain Gst is used as it is as the volume correction gain Gv.

  If it is determined in step S32 that the background noise level Pbgn is greater than or equal to the minimum background noise level TH_BGN_min (NO), the correction characteristic control unit 39 determines in step S34 that the background noise level Pbgn and the maximum background noise level TH_BGN_max When the background noise level Pbgn is determined to be smaller than the maximum background noise level TH_BGN_max (YES), a value obtained by correcting the standard volume correction gain Gst with the following equation is calculated as the volume correction gain Gv in step S35. To do. Here, γ is a positive fixed value. The correction gain is increased in accordance with the background noise level Pbgn to match the impression on hearing.

Gv = Gst + γ (Penv−Pbgn)
Further, when it is determined in step S34 that the background noise level Pbgn is equal to or higher than the maximum background noise level TH_BGN_max (NO), the correction characteristic control unit 39 determines in step S36 that the background noise level Pbgn and the final background noise level TH_BGN_end If the background noise level Pbgn is determined to be smaller than the final background noise level TH_BGN_end (YES), a value obtained by correcting the standard volume correction gain Gst with the following equation is calculated as the volume correction gain Gv in step S37. To do. Here, GAIN_bgn_max is (TH_BGN_max−TH_BGN_min), which is the maximum value of the volume correction gain corresponding to the background noise. The correction amount according to the background noise level Pbgn is suppressed to the maximum GAIN_bgn_max to prevent excessive correction.

Gv = Gst + GAIN_bgn_max
If it is determined in step S36 that the background noise level Pbgn is equal to or higher than the final background noise level TH_BGN_end (NO), the correction characteristic control unit 39 sets the standard volume correction gain Gst in the following equation in step S38. The corrected value is calculated as the volume correction gain Gv. When the environmental sound level Penv is equal to or higher than the final background noise level TH_BGN_end, the environmental sound is sufficiently loud, so the correction component corresponding to the background noise is reduced. Here, ζ is a positive fixed value.

Gv = Gst + GAIN_bgn_max−ζPenv
As shown in steps S33, S35, S37, and S38, the sound volume correction gain Gv is a value indicated by a one-dot chain line in FIG. 9 in consideration of the correction gain corresponding to the background noise level Pbgn. However, the area surrounded by the alternate long and short dash line and the thick line indicates not the environmental sound signal but the correction amount for the background noise level.

  After step S33, S35, S37, or S38, the correction characteristic control unit 39 performs the clipping process so that the volume correction gain Gv does not exceed the upper limit GAIN_max in step S39, and ends the process (step S40). . The correction gain characteristic that the correction characteristic control unit 39 gives to the equalizer control unit 37 includes the correction gain value Gm [k] supplied from the masking correction gain calculation unit 41 and the background noise level supplied from the background noise estimation unit 44. This is a characteristic obtained by adding a volume correction gain Gv generated based on Pbgn.

  According to the above-described embodiment, appropriate sound quality control can be performed for each frequency band according to the environmental sound, the signal level of background noise is estimated, and the correction gain characteristic is corrected according to the estimation result. As a result, it is possible to perform appropriate sound quality control processing that takes into account the background noise level when listening to the playback sound of the audio signal. Will be able to play.

  Further, when the background noise level is estimated, the tracking time of gain correction with respect to a change in the environmental sound can be improved by reducing the determination time according to the noise characteristic of the environmental sound.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by variously modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements according to different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 11 ... Digital television broadcast receiver, 12 ... Cabinet, 13 ... Support stand, 14 ... Video display panel, 15 ... Microphone, 16 ... Speaker, 17 ... Operation part, 17a ... Main power switch, 18 ... Remote controller, 19 ... Light receiving unit, 20 ... antenna, 21 ... input terminal, 22 ... tuner unit, 23 ... demodulation decoding unit, 24 ... signal processing unit, 25 ... synthesis processing unit, 26 ... audio processing unit, 27 ... video processing unit, 28 ... control 28a ... CPU, 28b ... memory unit, 29 ... HDD, 29a ... hard disk, 30 ... recording / playback processing unit, 31 ... input terminal, 32 ... network interface, 33 ... network network, 34 ... network server, 35 ... sound quality Control processing unit, 36 ... input terminal, 37 ... equalizer control unit, 38 ... output terminal, 39 ... correction characteristic control , 40 ... playback sound analysis unit, 41 ... masking correction gain calculation unit, 42 ... input terminal, 43 ... environmental sound analysis unit, 44 ... background noise estimator.

Claims (9)

Generating means for generating a first correction gain for masking correction for environmental sound with respect to an input audio signal;
An estimation means for estimating the background noise level from the environmental sound;
Based on the first correction gain generated by the generation unit and the second correction gain generated according to the background noise level estimated by the estimation unit, sound quality control processing is performed on the input audio signal. A sound quality control device comprising control means.   The sound quality control apparatus according to claim 1, wherein the estimation means sets a median value of signal power in a past short-term analysis section of environmental sound as a short-term background noise level.   The sound quality control apparatus according to claim 1, wherein the estimation unit estimates the background noise level by analyzing the short-term background noise level from an environmental sound over a long-term analysis section.   The sound quality control apparatus according to claim 3, wherein the estimation unit changes the length of the long-term analysis section based on a noise characteristic of the environmental sound.   The sound quality control device according to claim 4, wherein the estimation unit shortens the length of the long-term analysis section as the environmental sound is closer to a general noise characteristic.   The sound quality control apparatus according to claim 1, wherein the control means performs sound quality control processing on the input audio signal based on a characteristic obtained by adding the first correction gain and the second correction gain.   The sound quality control apparatus according to claim 1, wherein the control means performs an equalizer control process on the input audio signal. Generating a first correction gain for the masking correction for the environmental sound by the generation means for the audio signal;
Estimate the background noise level from the environmental sound by means of estimation,
A sound quality control method in which sound quality control processing is performed on the input audio signal by a control unit based on the first correction gain and the second correction gain generated according to the background noise level. Processing for generating a first correction gain for masking correction for environmental sound with respect to an input audio signal;
A process for estimating the background noise level from the environmental sound;
A sound quality control process for causing a computer to execute a sound quality control process on the input audio signal based on the first correction gain and the second correction gain generated according to the background noise level. program.

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