JP2019180073A - Acoustic system, sound-reproducing system, and sound reproduction method - Google Patents

Abstract

To calculate a compensation amount of audio signal becoming natural audibility for noise.SOLUTION: An acoustic system acquires first and second noise signals, acquires an audio signal, calculates noise level on the basis of the first and second noise signals, calculates the signal level of the audio signal, calculates a masking amount on the basis of the noise levels of the first and second noise signals and the signal level of the audio signal, controls frequency characteristics of the audio signal on the basis of the compensation amount of the audio signal determined based on the masking amount, and generates first and second output signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an acoustic system, an acoustic reproduction device, and an acoustic reproduction method.

  As a conventional sound reproduction device, the masking amount is calculated from an approximate expression expressed as a function of the difference between the noise signal level and the audio signal level for each frequency band, and the audio signal is changed by changing the frequency characteristics of the audio signal. A sound reproduction device that raises the level of sound is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-178695

  However, since the audio signal compensation amount is the same for all speakers in the above-described sound reproduction device, if the noise level at the binaural position is different on the left and right, the masking amount based on the noise level is different on the left and right. For example, there is a problem that the localization direction of the vocal moves in a direction where the noise level is small.

  One aspect of the present disclosure includes a first microphone that acquires a first noise signal, a second microphone that acquires a second noise signal, an audio signal input unit that inputs an audio signal, the first noise signal, and the first noise signal. A noise level analysis unit for calculating a noise level of each of the first noise signal and the second noise signal based on two noise signals; and a sound source signal analysis for calculating a signal level of the audio signal based on the audio signal A masking amount calculation unit that calculates a masking amount based on a noise level of the first noise signal, a noise level of the second noise signal, and a signal level of the audio signal, and based on the masking amount, A compensation amount calculation unit for determining a compensation amount of the audio signal and a frequency characteristic of the audio signal are controlled based on the calculated compensation amount, and the first output signal Beauty comprising a frequency characteristic controller for generating a second output signal, a first speaker and a second speaker to output the serial first output signal and said second output signal, respectively, and sound system.

  The present invention has been made in order to solve the conventional problems, and can provide a sound reproducing device that prevents changes in sound localization and sound spread regardless of noise.

1 is a block diagram illustrating an example of an acoustic system according to a first embodiment of the present disclosure. The block diagram which shows an example of the acoustic system in 2nd Embodiment of this indication. The figure which shows an example of the microphone installation position in the vehicle interior in embodiment of this indication Schematic representation of masking amount characteristics

  Hereinafter, an embodiment that specifically discloses a sound reproducing device according to the present disclosure will be described in detail with reference to the accompanying drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(First embodiment)
FIG. 1 is a block diagram illustrating an example of an acoustic system according to the first embodiment of the present disclosure. A first embodiment of the present disclosure will be described with reference to FIG. The acoustic system 1 includes an acoustic reproduction device 100, a first microphone 200, a second microphone 300, a sound source input device 400, a first speaker 500, and a second speaker 600. The sound reproduction device 100 includes a noise level analysis unit 101, a sound source signal analysis unit 102, a masking amount calculation unit 103, a compensation amount calculation unit 104, a frequency characteristic control unit 105, and a frequency characteristic control unit 106.

  The first microphone 200 and the second microphone 300 obtain a noise signal around the place where each is placed. The noise level analysis unit 101 analyzes the noise level for each frequency band based on the noise signals input from the first microphone 200 and the second microphone 300. The sound source signal analysis unit 102 analyzes the signal level of the two-channel audio signal including the first audio signal and the second audio signal output from the sound source input device 400 for each of one or more frequency bands. Here, the signal levels of the first audio signal and the second audio signal may be analyzed for each of one or more frequency bands.

  The masking amount calculation unit 103 calculates a masking amount for each frequency band based on the noise level analyzed by the noise level analysis unit 101 and the signal level analyzed by the sound source signal analysis unit 102.

  The compensation amount calculation unit 104 determines the compensation amount of the audio signal based on the masking amount calculated by the masking amount calculation unit 103 and calculates the equalizer gain used by the frequency characteristic control units 105 and 106.

  The frequency characteristic control unit 105 is controlled based on the equalizer gain calculated by the compensation amount calculation unit 104, and outputs the first output signal obtained by changing the equalizer gain for each frequency band with respect to the first audio signal to the first speaker 500. Output to.

  Similarly to the frequency characteristic control unit 105, the frequency characteristic control unit 106 is controlled based on the equalizer gain calculated by the compensation amount calculation unit 104, and changes the equalizer gain for each frequency with respect to the second audio signal. The output signal is output to the second speaker 600. Accordingly, the first speaker 500 and the second speaker 600 can reproduce the sound source by changing the output of the audio signal output from the sound source input device 400 according to the noise level.

  Here, a configuration example of the noise level analysis unit 101 will be described. The noise level analysis unit 101 may be configured by, for example, a frequency band divider and a level analyzer (not shown).

  The noise signal input to the noise level analysis unit 101 is divided into a plurality of frequency band signals by a frequency band divider.

  The frequency band divider is realized by time-frequency conversion processing such as a plurality of BPFs (Band Pass Filters) having different center frequencies or FFT (Fast Fourier Transform). The output signal of the frequency band divider is input to the level analyzer, and the level is analyzed for each frequency band. The analysis by the level analyzer is performed, for example, every time interval of several tens of ms to several hundreds of ms, which is a time resolution with which a human perceives loudness.

  Next, the sound source signal analysis unit 102 will be described. Similarly to the noise level analysis unit 101, the sound source signal analysis unit 102 may be configured by, for example, a frequency band divider and a level analyzer (not shown). At this time, since the operation of the sound source signal analysis unit 102 is the same as that of the noise level analysis unit 101 described above, a detailed description is omitted, but the frequency of the 2-channel audio signal input to the sound source signal analysis unit 102 is determined. An audio signal level is calculated for each band.

  Next, the operation of the masking amount calculation unit 103 will be described. When the audio signal is difficult to hear due to the presence of a noise signal in the user's viewing environment, the amount of masking required to make the sound louder than the sound of the audio signal when there is no noise signal Is known to have a high correlation with the difference between the audio signal level and the noise signal level.

When the noise signal level is N [dB] and the audio signal level is S [dB], the masking amount M [dB] can be approximated by the following (Equation 1). However, a, b, and c are constants.
M = a (S−N) ² + b (S−N) + c (Formula 1)

  FIG. 4 is a schematic diagram showing the masking amount characteristic. Specifically, it represents the masking amount for the noise signal level when the audio signal level is 70 dB. In FIG. 4, for example, when the noise signal level is 70 dB, the masking amount is about 7.3 dB. Therefore, when the audio signal level is 70 dB and the noise signal level is 70 dB, if the audio signal level is increased by 7.3 dB, the user can obtain the same audio signal level as when no noise signal exists in the viewing environment. Can be heard. Thus, the masking amount calculation unit 103 calculates the masking amount corresponding to the noise signal level for each frequency band.

  Next, the compensation amount calculation unit 104 will be described. The compensation amount calculation unit 104 determines the compensation amount so that the sound volume of the audio signal on hearing is constant at the user's binaural position in order to prevent changes in sound localization and sound spread.

  The frequency characteristic control unit 105 and the frequency characteristic control unit 106 output the first output signal and the second output signal obtained by changing the equalizer gain for each frequency band with respect to the two-channel audio signal based on the determined compensation amount. The signals are output to the first speaker 500 and the second speaker 600, respectively. The amount of compensation is determined in consideration of the outputs of the first speaker 500 and the second speaker 600 entering the user's both ears. In addition, the compensation amount calculation unit 104 determines the compensation amount for each time interval from several tens of ms to several hundreds of ms, which is the time resolution with which a human perceives the volume of sound, for example.

  As described above, according to the acoustic system 1 of the present disclosure, it is possible to control the output of an audio signal that has become difficult to hear due to a noise signal present in the viewing environment, and it is possible to prevent changes in sound localization and sound spread by the noise signal. This makes it possible to perform control with reduced discomfort.

  In the above embodiment, the noise signal is detected by the microphone. However, the noise signal at the binaural position of the user is estimated using a vehicle speed signal or an engine rotation pulse having a high correlation with the noise signal. Anyway.

  In that case, there is no need to install a microphone in the viewing environment of the user, and it is not necessary to analyze the noise signal detected by the microphone at the same time, and the system configuration can be simplified. In each embodiment including this embodiment, there may be a microphone in addition to the first microphone 200 and the second microphone 300. However, in this embodiment, the microphones are only the first microphone 200 and the second microphone 300. Will be described.

  In each of the embodiments including this embodiment, the sound source input device 400 may have at least one output channel. However, in this embodiment, the description will be made assuming that there are two output channels. When the output channel of the sound source input device 400 is one channel, the same signal is input to the frequency characteristic control unit 105 and the frequency characteristic control unit 106.

  In each embodiment including this embodiment, there may be a speaker in addition to the first speaker 500 and the second speaker 600. However, in this embodiment, the speaker is only the first speaker 500 and the second speaker 600. It will be explained as being.

  The sound reproducing device 100 may be realized by a digital signal processor (DSP) capable of performing digital signal processing, a microcomputer, or the like.

  Further, when the audio signal input from the sound source input device 400 is an analog signal, an A / D converter that converts the audio signal into a digital signal may be provided between the sound reproduction device 100 and the sound source input device 400.

  Further, a D / A converter for converting a digital signal into an analog signal and an amplifier for amplifying the signal may be provided between the sound reproducing device 100 and the first speaker 500 and the second speaker 600.

  Further, an A / D converter that converts an analog signal into a digital signal and an amplifier signal for amplifying the signal may be provided between the sound reproducing device 100 and the first microphone 200 and the second microphone 300. Furthermore, a binaural position noise analysis unit that estimates and analyzes a noise signal at the binaural position may be provided between the sound reproducing device 100 and the first microphone 200 and the second microphone 300.

  Although not shown in FIG. 1, the sound reproducing device 100 may include a noise signal input unit that receives noise signals from the first microphone 200 and the second microphone 300. Furthermore, the sound reproducing device 100 may include an audio signal input unit to which an audio signal is input from the sound source input device 400. In addition, the sound reproducing device 100 may include an audio signal output unit that outputs an audio signal to the first speaker 500 and the second speaker.

(Second Embodiment)
FIG. 2 is a block diagram illustrating an example of an acoustic system according to the second embodiment of the present disclosure. A second embodiment of the present disclosure will be described with reference to FIG. Note that a description of the same components as those in the first embodiment is omitted. The acoustic system 2 includes an acoustic reproduction device 800, a first microphone 200, a second microphone 300, a sound source input device 400, a first speaker 500, and a second speaker 600.

  The sound reproduction apparatus 800 includes a noise difference analysis unit 801, a noise amount calculation unit 802, a noise generation unit 803, a frequency characteristic control unit 804, a frequency characteristic control unit 805, an adder 806, an adder 807, a frequency characteristic control unit 808, noise A level analysis unit 101, a sound source signal analysis unit 102, a masking amount calculation unit 103, and a compensation amount calculation unit 104 are provided.

  Based on the analysis result of the noise level analysis unit 101, the noise difference analysis unit 801 calculates the left and right noise level difference amounts at the user's binaural positions for each frequency band. The noise amount calculation unit 802 determines a compensation amount based on the noise level difference amount output by the noise difference analysis unit 801, and uses the equalizer gain used in the frequency characteristic control unit 804 and the frequency characteristic control unit 805 for each frequency band. To calculate. Here, the noise amount calculation unit 802 calculates the equalizer gain for each frequency band so that the difference between the left and right noise levels at the user's binaural position is reduced.

  In addition, the noise amount calculation unit 802 may determine the compensation amount for each time interval of several tens of ms to several hundreds of ms, which is the time resolution with which a human perceives the volume of sound, for example.

  The noise generation unit 803 artificially generates a pseudo noise signal such as pink noise. Here, although the output channel of the noise generation unit 803 is described as being two channels, the output channel may be two or more channels.

  The noise generation unit 803 may generate a noise signal based on signals acquired from the first microphone 200 and the second microphone 300. The frequency characteristic control unit 804 controls the noise signal generated by the noise generation unit 803 for each frequency band with the equalizer gain calculated by the noise amount calculation unit 802. The frequency characteristic control unit 804 may control the noise signal with an individual equalizer gain for each of the two output channels, but may control with the same equalizer gain as in this embodiment. When the noise signal is controlled with the same equalizer gain for the two output channels, the system configuration is simplified. Here, the reason why the noise signal may be controlled with the same equalizer gain will be described.

  In this embodiment, the loudness of the noise signal is set to the same noise level on the left and right of the binaural position based on the equalizer gain calculated by the frequency characteristic control unit 804 and the frequency characteristic control unit 805. It is controlled to become. At this time, based on (Equation 1), if the noise signal level is the same at the left and right of the binaural position, the amount of audio signal masking is the same, so the noise signal is controlled using the same equalizer gain. I can say that.

  The frequency characteristic control unit 805 is controlled in the same manner as the frequency characteristic control unit 804. The sound reproducing device 800 may be realized by a digital signal processor (DSP) capable of performing digital signal processing, a microcomputer, or the like.

  Adder 806 adds the signal output from frequency characteristic control unit 805 to the signal output from frequency characteristic control unit 808, and outputs the result to first speaker 500. The adder 807 adds the signal output from the frequency characteristic control unit 804 to the signal output from the frequency characteristic control unit 808 and outputs the result to the second speaker 600.

  Although not shown in FIG. 2, the sound reproduction device 800 may include a noise signal input unit that receives noise signals from the first microphone 200 and the second microphone 300. Furthermore, the sound reproducing device 100 may include an audio signal input unit to which an audio signal is input from the sound source input device 400. In addition, the sound reproduction device 800 may include an audio signal output unit that outputs an audio signal to the first speaker 500 and the second speaker.

  FIG. 3 is a diagram illustrating an example of the microphone installation position in the vehicle interior according to the embodiment of the present disclosure. FIG. 3 shows an example of an arrangement position when the first microphone 200 and the second microphone 300 are arranged in the vehicle interior space of the vehicle 900. The first microphone 200 is installed at the installation position 901, and the second microphone 300 is installed at the installation position 902. Here, an example in which an installation position 901 and an installation position 902 exist on the left and right of the headrest in the driver's seat of the vehicle is shown. For example, when the noise level is different between the left and right of the binaural position, the amount of masking depending on the noise level is different between the left and right, so that the localization direction of the vocal moves in a direction where the noise level is small. If the first microphone 200 and the second microphone 300 are arranged in such a place, it is possible to detect noise in a place where the user (driver) actually views the audio signal, and to suppress the occurrence of such a problem. . Moreover, the place where the first microphone 200 and the second microphone 300 are installed is not limited to this, and the first microphone 200 and the second microphone 300 may be disposed anywhere as long as noises having different magnitudes can be detected on the left and right sides of the user's both ear positions. For example, a microphone having directivity may be arranged on a console panel of a vehicle to detect noises having different magnitudes on the left and right sides of the driver's both ears. Further, for example, it may be arranged on the left and right of the headrest of the passenger seat of the vehicle, and the noise at the binaural position of the user sitting on the passenger seat may be acquired.

DESCRIPTION OF SYMBOLS 1, 2 Sound system 100 Sound reproduction apparatus 101 Noise level analysis part 102 Sound source signal analysis part 103 Masking amount calculation part 104 Compensation amount calculation part 105 Frequency characteristic control part 106 Frequency characteristic control part 200 1st microphone 300 2nd microphone 400 Sound source input Device 500 First speaker 600 Second speaker 800 Sound reproduction device 801 Noise difference analysis unit 802 Noise amount calculation unit 803 Noise generation unit 804 Frequency characteristic control unit 805 Frequency characteristic control unit 806 First adder 807 Second adder 808 Frequency characteristic Control unit 900 Vehicle 901 First microphone installation position 902 Second microphone installation position

Claims (9)

A first microphone for acquiring a first noise signal;
A second microphone for acquiring a second noise signal;
An audio signal input section for inputting an audio signal;
A noise level analyzer that calculates a noise level of each of the first noise signal and the second noise signal based on the first noise signal and the second noise signal;
A sound source signal analyzer that calculates a signal level of the audio signal based on the audio signal;
A masking amount calculator that calculates a masking amount based on a noise level of the first noise signal, a noise level of the second noise signal, and a signal level of the audio signal;
A compensation amount calculation unit for determining a compensation amount of the audio signal based on the masking amount;
A frequency characteristic control unit that controls a frequency characteristic of the audio signal based on the calculated compensation amount and generates a first output signal and a second output signal;
A first speaker and a second speaker for outputting the first output signal and the second output signal, respectively.
Acoustic system. The frequency characteristic control unit generates the first output signal and the second output signal by changing an equalizer gain of the audio signal based on the compensation amount.
The acoustic system according to claim 1. The compensation amount calculation unit calculates the compensation amount for each of one or more frequency bands.
The acoustic system according to claim 1. The frequency characteristic control unit changes the equalizer gain of the audio signal for each of the one or more frequency bands based on the compensation amount, and generates the first output signal and the second output signal.
The acoustic system according to claim 3. The first noise signal indicates noise near the viewer's left ear at a predetermined viewing position; the second noise signal indicates noise near the viewer's right ear at the predetermined viewing position;
The compensation amount calculation unit is configured so that the first output signal and the second output signal output from the first speaker and the second speaker have the same sound volume at the binaural position of the viewer. Calculate the compensation amount,
The acoustic system according to any one of claims 1 to 4. A noise difference analyzer for analyzing a noise level difference between the first noise signal and the second noise signal;
A noise generator that generates a predetermined noise signal based on the noise level difference;
An adder for adding the controlled noise signal to the audio signal;
The acoustic system according to claim 1. The audio signal is a signal of at least two channels including a first audio signal and a second audio signal.
The acoustic system according to any one of claims 1 to 6. A noise signal input unit for inputting a first noise signal representing noise at the first point and a second noise signal representing noise at the second point;
An audio signal input section for inputting an audio signal;
A noise level analyzer that calculates a noise level of each of the first noise signal and the second noise signal based on the first noise signal and the second noise signal;
A sound source signal analyzer that calculates a signal level of the audio signal based on the audio signal;
A masking amount calculator that calculates a masking amount based on a noise level of the first noise signal, a noise level of the second noise signal, and a signal level of the audio signal;
A compensation amount calculation unit for determining a compensation amount of the audio signal based on the masking amount;
A frequency characteristic control unit that controls a frequency characteristic of the audio signal based on the calculated compensation amount and generates a first output signal and a second output signal;
An output unit for outputting the generated first output signal and the second output signal;
A sound reproducing device comprising: Obtaining a first noise signal representing noise at a first point and a second noise signal representing noise at a second point;
Obtaining an audio signal;
Calculating a noise level of each of the first noise signal and the second noise signal based on the first noise signal and the second noise signal;
Calculating a signal level of the audio signal based on the audio signal;
Calculating a masking amount based on a noise level of the first noise signal, a noise level of the second noise signal, and a signal level of the audio signal;
Determining a compensation amount for each of the audio signals based on the masking amount;
Controlling a frequency characteristic of the audio signal based on the calculated compensation amount, and generating a first output signal and a second output signal;
Outputting the generated first output signal and the second output signal;
A sound reproduction method comprising:

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