Acoustic processing apparatus and acoustic processing method

Abstract

To provide an acoustic processing device and an acoustic processing method that can make a sound source easy-to-hear.SOLUTION: An acoustic processing device according to an embodiment includes a detection unit and a correction unit. The detection unit detects a residual amount of noise in a cabin of a vehicle cancelled by noise cancellation processing for cancelling noise in the cabin. The correction unit corrects an output sound volume of a sound source to be output to the cabin based on the residual amount.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an acoustic processing apparatus and an acoustic processing method.

Background Art

[0002] Conventionally, an acoustic processing apparatus having a function of ANC (Active Noise Cancellation) that actively cancels noise such as engine noise and road noise flowing in a vehicle interior has been known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, due to vehicle performance, there are cases where noise cannot be completely canceled, and in such cases, there is a risk that sound sources such as audio may become difficult to hear due to the remaining noise.

[0005] The present invention has been made in view of the above, and an object thereof is to provide an acoustic processing apparatus and an acoustic processing method capable of making a sound source easier to hear.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, an acoustic processing apparatus according to the present invention includes a detection unit and a correction unit. The detection unit detects a remaining amount in the interior of the noise that has been canceled by noise cancellation processing for canceling noise in the interior of the vehicle. The correction unit corrects the output volume of a sound source output to the interior based on the remaining amount.

Effects of the Invention

[0007] According to the present invention, the sound source can be made easier to hear.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of an acoustic processing apparatus and an acoustic processing method disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments shown below.

[0010] First, with reference to FIG. 1, an outline of an acoustic processing method according to an embodiment will be described. FIG. 1 is a diagram showing an outline of an acoustic processing method according to an embodiment. The acoustic processing method according to the embodiment is executed by the acoustic processing apparatus 1 shown in FIG. 1.

[0011] In the acoustic processing method according to the embodiment, the residual amount in the vehicle interior of the noise that has been canceled by noise canceling processing for canceling the noise flowing in the vehicle interior C is detected, and the output volume of the sound source output to the interior is corrected based on the residual amount.

[0012] First, the noise cancellation process will be described with reference to FIG. 1. As shown in FIG. 1, in the noise cancellation process, a first processing unit 231, a second processing unit 232, a third processing unit 233, a fourth processing unit 234, and a fifth processing unit 235 execute processes.

[0013] The first processing unit 231 acquires the engine speed and generates a reference signal based on the engine speed. The second processing unit 232 inputs the generated reference signal into a transfer function to calculate a predicted value of the cancellation sound. The third processing unit 233 multiplies the sound (residual amount) collected by the microphone 100 and the predicted value calculated by the second processing unit 232 to update the filter coefficients of the adaptive filter of the fourth processing unit 234. That is, the microphone 100 is for monitoring the cancellation effect of the noise cancellation process by collecting the indoor sound.

[0014] The fourth processing unit 234 generates a cancellation sound that cancels the noise by inputting the reference signal into the adaptive filter with updated filter coefficients. The fifth processing unit 235 limits the output of the cancellation sound by a limiter to prevent the system from being damaged due to excessive output of the cancellation sound.

[0015] In this way, in the noise cancellation process, the cancellation sound is generated by executing the first processing unit 231 to the fifth processing unit 235.

[0016] Here, as shown in FIG. 1, in the interior of the vehicle C, in addition to the cancellation sound, a sound source may be output from the speaker 200. In such a case, when the noise is not sufficiently canceled by the cancellation sound, there is a risk that the remaining noise will mask the sound source and make it difficult to hear the sound source.

[0017] Therefore, in the acoustic processing method according to the embodiment, the output volume of the sound source is corrected according to the residual amount of the noise. Specifically, in the acoustic processing method according to the embodiment, first, the residual amount of the noise canceled by the cancellation sound in the room is detected.

[0018] In the acoustic processing method according to the embodiment, the output volume of the sound source is corrected based on the detected residual amount. In the example shown in FIG. 1, based on the detected residual amount, the gain of the amplifier 261 (hereinafter referred to as the compensation gain) is determined and applied to the amplifier 261.

[0019] As a result, the output volume of the sound source increases by the amount of the compensation gain by the amplifier 261. Then, the sound source whose output volume has increased by the amplifier 261 is mixed with the cancellation sound by the mixer 271 and output from the speaker 200.

[0020] That is, in the acoustic processing method according to the embodiment, the output volume of the sound source is corrected so as to increase by the amount of the residual amount of the noise. Thereby, even when noise remains in the room, the sound source can be made easier to hear due to the increase in the output volume.

[0021] In FIG. 1, the engine sound is taken as an example of the noise, but for example, the road noise in an electric vehicle not equipped with an engine may be used as the noise. When the noise is road noise, the first processing unit 231 generates a reference signal based on the acceleration detected by the acceleration sensor.

[0022] In FIG. 1, a configuration is shown in which the residual amount is detected from the sound collected by the microphone 100 for monitoring the cancellation effect of the noise cancellation process. Thereby, since it is not necessary to prepare a dedicated microphone for detecting the residual amount, the cost can be suppressed.

[0023] Next, the configuration of the acoustic processing apparatus 1 according to the embodiment will be described with reference to FIG. 2. FIG. 2 is a block diagram showing the configuration of the acoustic processing apparatus 1 according to the embodiment. As shown in FIG. 2, the acoustic processing apparatus 1 according to the embodiment is connected to the microphone 100, the rotation speed sensor 110, and the speaker 200. In FIG. 2, a configuration example in which the cancellation sound and the sound source are output from one speaker 200 is shown, but a configuration in which the cancellation sound and the sound source are output from separate speakers 200 may be used.

[0024] The microphone 100 is a sound collection device that detects sounds inside the vehicle C. As described above, the microphone 100 is a microphone that monitors the cancellation effect of the noise cancellation process by the subsequent ANC unit 23.

[0025] In the example shown in FIG. 2, the microphone 100 has a configuration that serves both for the noise cancellation process by the ANC unit 23 and for the detection process of the residual amount by the detection unit 22. However, the noise cancellation process by the ANC unit 23 and the detection process of the residual amount by the detection unit 22 may be configured with separate microphones 100.

[0026] The rotation speed sensor 110 is a sensor that detects the engine rotation speed of the vehicle C. As described above, when the noise is load noise, an acceleration sensor is used instead of the rotation speed sensor 110.

[0027] The speaker 200 is an output device that is arranged inside the vehicle C (for example, in the door part) and outputs the cancellation sound and the simulated sound toward the inside of the vehicle.

[0028] As shown in FIG. 2, the acoustic processing device 1 according to the embodiment includes a control unit 2 and a storage unit 3. The control unit 2 includes an acquisition unit 21, a detection unit 22, an ANC unit 23, a sound source reproduction unit 24, a sound source processing unit 25, a correction unit 26, and an output unit 27. The storage unit 3 stores compensation gain information 31.

[0029] Note that the configuration example shown in FIG. 2 is just an example. For example, the functional blocks related to the noise cancellation process (the acquisition unit 21 and the ANC unit 23) may be configured as separate devices.

[0030] Here, the acoustic processing device 1 includes, for example, a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a data flash, input / output ports, etc., and various circuits.

[0031] The CPU of the computer functions as the acquisition unit 21, detection unit 22, ANC unit 23, sound source playback unit 24, sound source processing unit 25, correction unit 26, and output unit 27 of the control unit 2, for example, by reading and executing a program stored in the ROM.

[0032] Also, at least one or all of the acquisition unit 21, detection unit 22, ANC unit 23, sound source playback unit 24, sound source processing unit 25, correction unit 26, and output unit 27 of the control unit 2 can be configured by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0033] Also, the storage unit 3 corresponds to, for example, a RAM or a data flash. The RAM or the data flash can store compensation gain information 31, information on various programs, and the like. Note that the acoustic processing device 1 may acquire the above-described program and various information via another computer connected by a wired or wireless network or a portable recording medium.

[0034] The compensation gain information 31 is information for determining the compensation gain by the subsequent correction unit 26. FIG. 3 is a diagram showing an example of the compensation gain information 31. As shown in FIG. 3, the compensation gain information 31 includes items such as "residual amount (dBA)" and "compensation gain".

[0035] The "residual amount (dBA)" is information detected by the subsequent detection unit 22 and indicates the residual amount of noise in the room. The "compensation gain" is information indicating the correction value of the output volume by the subsequent correction unit 26 and is the gain of the amplifier 261 described above.

[0036] Next, each function (acquisition unit 21, detection unit 22, ANC unit 23, sound source playback unit 24, sound source processing unit 25, correction unit 26, and output unit 27) of the control unit 2 will be described.

[0037] The acquisition unit 21 acquires various types of information. For example, the acquisition unit 21 acquires information on the sound inside the room input to the microphone 100. Also, the acquisition unit 21 acquires information on the engine rotational speed detected by the rotational speed sensor 110.

[0038] Based on the sound information acquired by the acquisition unit 21, the detection unit 22 detects the loudness of the sound and detects the detected loudness of the sound as the residual amount of the noise.

[0039] The ANC unit 23 has the above-described first processing unit 231 to fifth processing unit 235, and generates a cancellation sound for canceling the noise. Specifically, first, the first processing unit 231 of the ANC unit 23 generates a reference signal based on the engine rotational speed detected by the rotational speed sensor 110.

[0040] Subsequently, the second processing unit 232 inputs the generated reference signal into the transfer function to calculate a predicted value of the cancellation sound. The third processing unit 233 multiplies the sound collected by the microphone 100 and the predicted value of the cancellation sound calculated by the second processing unit 232 to update the filter coefficient of the adaptive filter of the fourth processing unit 234.

[0041] The fourth processing unit 234 inputs the reference signal into the adaptive filter with the updated filter coefficient to generate a cancellation sound for canceling the noise. The fifth processing unit 235 prevents the system from being damaged due to excessive output of the cancellation sound by limiting the output of the cancellation sound with a limiter.

[0042] Then, the ANC unit 23 outputs the information on the cancellation sound output from the fifth processing unit 235 to the output unit 27.

[0043] The sound source playback unit 24 plays back the sound source to be played inside the vehicle C. For example, the sound source playback unit 24 plays back the sound source designated by the operation of the occupant. Examples of the sound source include music, video audio, system sounds of the navigation device, and the like.

[0044] The sound source processing unit 25 performs audio processing on the sound source reproduced by the sound source playback unit 24. Specifically, the sound source processing unit 25 performs audio processing such as processing by an equalizer, time alignment, and volume adjustment.

[0045] The sound source processing unit 25 outputs the sound source subjected to audio processing to the correction unit 26.

[0046] The correction unit 26 corrects the output volume of the sound source input from the sound source processing unit 25 based on the remaining amount detected by the detection unit 22. Specifically, the correction unit 26 refers to the compensation gain information 31 stored in the storage unit 3 and calculates (determines) the compensation gain corresponding to the remaining amount.

[0047] Subsequently, the correction unit 26 corrects the output volume of the sound source by inputting the sound source to which the calculated compensation gain is applied to the amplifier 261 (see FIG. 1). The correction unit 26 outputs the sound source after correcting the output volume to the output unit 27.

[0048] The output unit 27 mixes the sound source input from the correction unit 26 and the cancellation sound input from the ANC unit 23 by the mixer 271 and outputs it from the speaker 200 to the room.

[0049] Next, with reference to FIG. 4, the processing procedure of the sound source correction process executed by the acoustic processing device 1 according to the embodiment will be described. FIG. 4 is a flowchart showing the processing procedure of the sound source correction process executed by the acoustic processing device 1 according to the embodiment.

[0050] As shown in FIG. 4, first, the acquisition unit 21 acquires the sound flowing into the room from the microphone 100 (step S101).

[0051] Subsequently, the detection unit 22 detects the remaining amount of the noise remaining in the room based on the acquired sound (step S102).

[0052] Subsequently, the correction unit 26 refers to the compensation gain information 31 and calculates the compensation gain from the detected remaining amount (step S103).

[0053] Subsequently, the correction unit 26 corrects the output volume of the sound source based on the calculated compensation gain (step S104) and ends the process.

[0054] As described above, the acoustic processing apparatus 1 according to the embodiment includes a detection unit 22 and a correction unit 26. The detection unit 22 detects the residual amount in the vehicle interior of the noise that has been canceled by the noise cancellation process for canceling the noise in the vehicle interior C. The correction unit 26 corrects the output volume of the sound source output to the interior based on the residual amount. Thereby, it is possible to make the sound source easier to hear.

[0055] In the above-described embodiment, the residual amount is detected from the sound collected by the microphone 100. However, for example, the residual amount in the frequency band other than the specific frequency band among the collected sounds may be detected. This point will be described with reference to FIG. 5.

[0056] FIG. 5 is a diagram showing an acoustic processing method according to Modification 1. As shown in FIG. 5, in Modification 1, the acoustic processing apparatus 1 further includes a band filter 28. The band filter 28 is a filter that blocks a specific frequency band among the sounds collected by the microphone 100. The band filter 28 can use various filters such as a low-pass filter, a high-pass filter, and a band-pass filter.

[0057] For example, the band filter 28 blocks a specific frequency band that is canceled by the noise cancellation process. That is, the detection unit 22 detects the residual amount in the frequency band other than the specific frequency band. Then, the correction unit 26 corrects the output volume of the frequency band other than the specific frequency band among the frequency bands of the sound source based on the residual amount.

[0058] This is because the specific frequency band is canceled by noise cancellation processing, resulting in good audibility of the sound source. Therefore, if the output volume is corrected up to a specific frequency band, the volume balance with frequency bands other than the specific frequency band may be disrupted. Thus, according to Modification 1, by not correcting the output volume of the specific frequency band, it is possible to highly accurately avoid variations in the way the sound source is heard (volume) between the specific frequency band and other frequency bands.

[0059] In FIG. 5, output correction is not performed for the specific frequency band to which noise cancellation processing is applied. However, for example, output correction according to the influence of each frequency band of the noise may be performed.

[0060] Specifically, the detection unit 22 first detects the residual amount for each predetermined frequency band. Subsequently, the correction unit 26 corrects the output volume for each predetermined frequency band for the sound source. Thereby, flexible output correction such as performing output correction according to the influence of each frequency band of the noise is made possible.

[0061] Also, as another modification, there is a method of detecting the residual amount by removing the component of the sound source from the sound collected by the microphone 100. This point will be described with reference to FIG. 6.

[0062] FIG. 6 is a diagram showing an acoustic processing method according to Modification 2. As shown in FIG. 6, in Modification 2, the acoustic processing apparatus 1 further includes a second processing unit 221 and a logic circuit 222.

[0063] The second processing unit 221 has the same transfer function as the above-described second processing unit 232, and inputs the sound source output from the amplifier 261 into the transfer function to calculate a predicted value of the sound source in the room.

[0064] The logic circuit 222 is a circuit that subtracts the predicted value calculated by the second processing unit 221 from the sound collected by the microphone 100. That is, the logic circuit 222 performs processing to remove the component of the sound source from the sound input to the microphone 100.

[0065] Then, the detection unit 22 detects the remaining amount based on the signal obtained by removing the sound source component from the sound input to the microphone 100. And the subsequent correction unit 26 calculates the compensation gain based on the remaining amount excluding the influence of the sound source. Thereby, for example, it is possible to highly accurately avoid erroneously detecting that the noise increases when the volume of the sound source is increased.

[0066] Further effects and modifications can be easily derived by those skilled in the art. For this reason, the broader aspects of the present invention are not limited to the specific details and representative embodiments represented and described as above. Therefore, various changes can be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

Explanation of Reference Numerals

[0067] 1 Acoustic processing device 2 Control unit 3 Storage unit 21 Acquisition unit 22 Detection unit 23 ANC unit 24 Sound source playback unit 25 Sound source processing unit 26 Correction unit 27 Output unit 28 Band filter 31 Compensation gain information 100 Microphone 110 Rotation speed sensor 200 Speaker 221 Second processing unit 222 Logic circuit 231 First processing unit 232 Second processing unit 233 Third processing unit 234 Fourth processing unit 235 Fifth processing unit 261 Amplifier 271 Mixer C Vehicle

Claims

1. A detection unit that detects the residual amount in the vehicle interior of the noise that has been canceled by noise cancellation processing for generating a cancellation sound that cancels the noise in the vehicle interior; A correction unit that corrects the output volume of a sound source output to the interior based on the residual amount; The acoustic processing apparatus is provided with: The noise cancellation processing is: Processing for canceling the noise in a specific frequency band; The detection unit is: Detecting the residual amount for each predetermined frequency band and detecting the residual amount in a frequency band other than the specific frequency band; The correction unit is: For the sound source, correcting the output volume for each predetermined frequency band and correcting the output volume in a frequency band other than the specific frequency band among the frequency bands of the sound source; An acoustic processing apparatus characterized by the above.

2. The detection unit is: Detecting the residual amount based on the sound input to a microphone that monitors the cancellation effect of the noise cancellation processing; The acoustic processing apparatus according to claim 1, characterized by the above.

3. The detection unit is: Detecting the residual amount based on a signal obtained by removing the component of the sound source from the sound input to the microphone; The acoustic processing apparatus according to claim 2, characterized by the above.

4. A detection step of detecting the residual amount in the vehicle interior of the noise that has been canceled by noise cancellation processing for generating a cancellation sound that cancels the noise in the vehicle interior; A correction step of correcting the output volume of a sound source output to the interior based on the residual amount; The acoustic processing method includes: The noise cancellation processing is: Processing for canceling the noise in a specific frequency band; The detection step is: Detecting the residual amount for each predetermined frequency band and detecting the residual amount in a frequency band other than the specific frequency band; The correction step is: For the sound source, correcting the output volume for each predetermined frequency band and correcting the output volume in a frequency band other than the specific frequency band among the frequency bands of the sound source; An acoustic processing method characterized by the above.

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