Sound field correction apparatus, sound field correction method, and non-volatile storage medium

Abstract

The present application relates to a sound field correction apparatus, a sound field correction method, and a non-volatile storage medium, which effectively suppress the impact caused by a time difference of arrival of sounds from a plurality of loudspeakers. The sound field correction apparatus is used for measuring sounds output from a plurality of loudspeakers at a designated listening position, and comprises: an output control unit configured to control so that a plurality of loudspeakers output sounds in different frequency bands of the plurality of loudspeakers; a receiving unit configured to receive information of the output sounds; a calculation unit configured to perform frequency analysis processing on the plurality of loudspeakers by using the received information of the sounds, and calculate a time difference of arrival of sounds output from the plurality of loudspeakers to the listening position; and a correction unit configured to correct an output moment of the plurality of loudspeakers on the basis of the time difference.

Description

Sound field correction device, sound field correction method and non-volatile storage medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Japanese patent application No. 2024-046841, filed with the Japan Patent Office on March 22, 2024, and entitled “Sound field correction device, sound field correction method and program,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a sound field correction device, a sound field correction method and a non-volatile storage medium. Background Art

[0004] In audio devices that output sound from multiple speakers, sound dispersion may occur because the sound output from each speaker arrives at the listening position at different times. One method to address this problem is to use a microphone to capture a test tone output from each speaker, measure the time it takes for the tone to reach the microphone for each speaker, and calculate the delay time based on the measured time.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Utility Model Application Laid-Open No. 6-013292

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2002-330500. Summary of the Invention

[0009] The above calculation method requires measurement and calculation of the delay time at each speaker, so the measurement work takes time.

[0010] The problem to be solved by the embodiments of the present application is to provide a sound field correction device, a sound field correction method, and a program that effectively suppress the influence of the arrival time difference of sounds in a plurality of speakers.

[0011] The sound field correction device of the embodiment is a sound field correction device that measures the sounds output from multiple speakers at a specified listening position, and includes: an output control unit that controls so that sounds with different frequency bands are output from the multiple speakers; a receiving unit that receives information about the output sounds; a calculation unit that uses the received sound information to perform frequency analysis processing on each of the multiple speakers and calculates the time difference between the sounds output from the multiple speakers reaching the listening position; and a correction unit that corrects the output timing of the multiple speakers based on the time difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] 1 is a block diagram showing an example of a hardware configuration of an audio device according to an embodiment;

[0013] 2 is a block diagram showing an example of a functional configuration of a sound field correction device according to an embodiment;

[0014] FIG3 is a diagram for explaining an example of a method for calculating an impulse response according to an embodiment;

[0015] FIG4 is a diagram showing an example of a measurement signal according to the embodiment;

[0016] FIG5 is a diagram showing an example of a TSP signal and an inverse TSP signal in one frequency band according to an embodiment;

[0017] FIG6 is a diagram showing an example of calculation results of an impulse response according to the embodiment;

[0018] 7 is a flowchart showing an example of processing in the sound field correction device according to the embodiment;

[0019] FIG. 8 is a diagram illustrating an example of a measuring method according to the second embodiment.

[0020] DESCRIPTION OF REFERENCE NUMERALS 1 ... audio device, 5 ... sound field correction device, 11 ... CPU, 12 ... memory, 13 ... storage, 14 ... user I / F, 15…communication I / F, 20…communication bus, 21…sound decoder, 22…sound input ADC, 23…DSP, 25A…first delay circuit, 25B…second delay circuit, 25C…third delay circuit, 31A…first speaker, 31B…second speaker, 31C…third speaker, 31D…fourth speaker, 41…remote controller, 45…microphone, 46…wireless modulation circuit, 47…transmitter, 101…sound output control unit, 102…test tone output control unit, 103…receiving unit, 104…recording unit, 105…calculation unit, 106…correction unit, AS1, AS2, AS3…sound, TS1…first test tone, TS2…second test tone, TS3…third test tone, St…acoustic signal, m1…first output tone, w1…second output tone, a1…third output tone, a4…fourth output tone. DETAILED DESCRIPTION

[0021] Hereinafter, exemplary embodiments of the sound field correction device 5 of the present application and the sound field correction device 5 for executing the sound field correction method will be disclosed.

[0022] 1 is a block diagram showing an example of the hardware configuration of an audio device 1 according to an embodiment. The audio device 1 is a device capable of outputting sound from a plurality of speakers, and may be, for example, a stereo, a video player, a video recorder, a television, or a home theater system.

[0023] The audio device 1 of this embodiment includes a sound field correction device 5 , a first speaker 31A, a second speaker 31B, a third speaker 31C, and a remote controller 41 .

[0024] Sound field correction device 5 performs sound field correction processing. In this sound field correction processing, the output timing of sounds AS1, AS2, and AS3 outputted from first speaker 31A, second speaker 31B, and third speaker 31C is optimized based on the positional relationship between these speakers and the user's listening position, thereby reducing the arrival time difference between the sounds outputted from each speaker. In this embodiment, the listening position is the position of remote control 41.

[0025] The sound field correction device 5 of this embodiment includes a CPU (Central Processing Unit) 11, a memory 12, a storage 13, a user I / F (Interface) 14, a communication I / F 15, a sound decoder 21, a sound input ADC (Analog to Digital Converter) 22, a DSP (Digital Signal Processor) 23, a first delay circuit 25A, a second delay circuit 25B and a third delay circuit 25C. These structural elements are connected to each other for communication via a communication bus 20.

[0026] The CPU 11 performs predetermined calculations and control processes according to programs (including firmware, application software, etc.) stored in the memory 12, etc. The memory 12 is a main storage device including RAM (Random Access Memory) and ROM (Read Only Memory), and functions as a program storage area and a work area for the CPU 11. The memory 13 is an auxiliary storage device including non-volatile memory such as an SSD (Solid State Drive) and an HDD (Hard Disk Drive), which enables the writing and reading of various data. The user I / F 14 is a device that enables the reception of input from the user and the output of information to the user, and may be, for example, a display or input buttons. The communication I / F 15 is a device that enables communication with other electronic devices connected via a predetermined communication network. The communication I / F 15 of this embodiment establishes wireless communication with the remote control 41 in accordance with a predetermined standard.

[0027] The audio decoder 21 converts audio data recorded on a specified medium (e.g., CDs, DVDs, Blu-ray discs, portable media, etc.), audio data included in broadcast waves, or audio data acquired from a network such as a CSP (Communications Service Provider) into digital signals that can be output from the first speaker 31A, second speaker 31B, and third speaker 31C. The audio input ADC 22 converts analog audio signals input from an external device into digital signals.

[0028] DSP23 is a processor that performs prescribed processing on digital signals corresponding to the sounds output from the first speaker 31A, the second speaker 31B, and the third speaker 31C, and generates sound signals of the sounds AS1, AS2, and AS3 to be listened to, and sound signals of the first test sound TS1, the second test sound TS2, and the third test sound TS3 to be described later.

[0029] The first delay circuit 25A delays the output timing of the sound AS1 output from the first speaker 31A based on the correction signal (delay signal) output from the CPU 11. The second delay circuit 25B delays the output timing of the sound AS2 output from the second speaker 31B based on the correction signal output from the CPU 11. The third delay circuit 25C delays the output timing of the sound AS3 output from the third speaker 31C based on the correction signal output from the CPU 11.

[0030] Remote control 41 is a device that can be operated by a user who wishes to listen to sounds AS1, AS2, and AS3. It includes a microphone 45, a wireless modulation circuit 46, and a transmitter 47. Microphone 45 converts captured sounds into electrical signals (analog signals). Wireless modulation circuit 46 modulates the electrical signals generated by microphone 45 into a signal (digital signal) that can be used for wireless communication in accordance with a specified standard. Transmitter 47 transmits the signals modulated by wireless modulation circuit 46 to sound field correction device 5.

[0031] It should be noted that, in addition to the above, the remote control 41 is also provided with buttons and the like for receiving user operations, but description thereof is omitted here. In addition, in this embodiment, the remote control 41 is illustrated as having a microphone 45, but the microphone 45 may also be an independent device.

[0032] The sound field correction device 5 of this embodiment is a sound field correction device 5 that measures the sounds output from multiple speakers at a specified listening position, and includes: an output control unit that controls so that sounds with different frequency bands are output from the multiple speakers; a receiving unit 103 that receives information on the output sounds; an operation unit 105 that uses the received sound information to perform frequency analysis processing on each of the multiple speakers and calculates the time difference between the sounds output from the multiple speakers reaching the listening position; and a correction unit 106 that corrects the output timing of the speakers based on the time difference.

[0033] Specifically, when executing the sound field correction process, the sound field correction device 5 of this embodiment causes the first test tone TS1, the second test tone TS2, and the third test tone TS3 to be simultaneously output from the first speaker 31A, the second speaker 31B, and the third speaker 31C. The TSP signal of the frequency band of the first test tone TS1, the TSP signal of the frequency band of the second test tone TS2, and the TSP signal of the frequency band of the third test tone TS3 are in different frequency bands.

[0034] Microphone 45 mounted on remote controller 41 acquires a composite sound including first test sound TS1 , second test sound TS2 , and third test sound TS3 , and transmitter 47 transmits an acoustic signal St of the composite sound acquired by microphone 45 to sound field correction device 5 .

[0035] The sound field correction device 5 analyzes the frequency components contained in the acoustic signal St received from the remote control 41. Specifically, it performs frequency analysis by multiplying each TSP signal by its corresponding inverse TSP signal. It then obtains the respective maximum amplitude values ​​from the calculated impulse responses. Based on the analysis results, it calculates the arrival time t1 of the first test tone TS1 from the first speaker 31A to the microphone 45, the arrival time t3 of the second test tone TS2 from the second speaker 31B to the microphone 45, and the arrival time t2 of the third test tone TS3 from the third speaker 31C to the microphone 45. The time difference between the arrival times of the first test tone TS1 from the first speaker 31A to the microphone 45 is also calculated. Furthermore, the amplitude of each speaker is calculated. Specifically, the time difference Δt1 between the first speaker 31A and the second speaker 31B, the time difference Δt2 between the second speaker 31B and the third speaker 31C, and the time difference Δt3 between the first speaker 31A and the third speaker 31C are calculated.

[0036] The sound field correction device 5 then performs processing to correct at least one of the output timings of sound AS1 from the first speaker 31A, sound AS2 from the second speaker 31B, and sound AS3 from the third speaker 31C based on the calculated time difference. Specifically, the device performs delay processing to control the first delay circuit 25A, the second delay circuit 25B, or the third delay circuit 25C. Furthermore, the amplitude of at least one speaker is corrected based on the calculated amplitude difference to approach the target amplitude difference. Note that the test tone may also be an output sound.

[0037] It should be noted that, when the sound field correction device 5 of this embodiment does not include the third speaker 31C, the first test tone TS1 and the second test tone TS2 are simultaneously output from the first speaker 31A and the second speaker 31B during the sound field correction process. The TSP signal of the frequency band of the first test tone TS1 and the TSP signal of the frequency band of the second test tone TS2 are in different frequency bands.

[0038] The microphone 45 mounted on the remote controller 41 acquires a composite sound including the first test sound TS1 and the second test sound TS2 , and the transmitter 47 transmits the acoustic signal St of the composite sound acquired by the microphone 45 to the sound field correction device 5 .

[0039] The sound field correction device 5 analyzes the frequency components contained in the acoustic signal St received from the remote control 41. Specifically, it performs frequency analysis by multiplying each TSP signal by the corresponding inverse TSP signal. The device then obtains the respective maximum amplitude values ​​from the calculated impulse responses. Based on the analysis results, it calculates the time difference Δt1 between the arrival time t1 of the first test tone TS1 from the first speaker 31A to the microphone 45 and the arrival time t3 of the second test tone TS2 from the second speaker 31B to the microphone 45. Furthermore, the volume difference between the speakers is calculated based on the amplitudes.

[0040] The sound field correction device 5 then performs processing to correct at least one of the output timings of sound AS1 from the first speaker 31A and sound AS2 from the second speaker 31B based on the calculated time difference Δ1. In other words, it performs processing to control the first delay circuit 25A or the second delay circuit 25B. Furthermore, the amplitude of at least one speaker is corrected based on the calculated amplitude difference to approach the target amplitude difference. The test tone can also be an output sound.

[0041] FIG2 is a block diagram illustrating an example of the functional configuration of a sound field correction device 5 according to an embodiment. The sound field correction device 5 according to this embodiment includes a sound output control unit 101, a test sound output control unit 102, a receiving unit 103, a recording unit 104, a computing unit 105, a correction unit 106, a memory 12, and a sound decoder 21. These functional units 101-106, 12, and 21 can be implemented through the collaboration of hardware and software (programs) as illustrated in FIG1. ​​Alternatively, at least a portion of these functional units 101-106, 12, and 21 may be implemented using dedicated hardware (e.g., circuits).

[0042] The sound field correction device 5, for example, uses the test sound output control unit 102 of the DSP 23 to control the output of an acoustic signal St from each speaker. The acoustic signal St is then received by the receiving unit 103 of the communication I / F 15. It is then stored in the recording unit 104 of the memory 13. Furthermore, the TSP signal acquired by the calculation unit 105 of the CPU 11 undergoes frequency analysis. The calculation unit 105 calculates the time difference between each speaker reaching the listening position. The correction unit 106 of the DSP 23 controls the delay circuits 25A, 25B, and 25C to correct the output timing of each speaker. The sound output control unit 101 of the DSP 23 then controls the output of sound from each speaker by receiving a digital signal from the sound decoder 21. The calculation unit 105 acquires the target amplitude for each speaker from the memory 12, and the correction unit 106 corrects the amplitude output from each speaker. It should be noted that the correspondence between the functional components and the hardware components is merely an example.

[0043] The sound output control unit 101 is exemplified by a function executed by the DSP 23. The sound output control unit 101 controls so that the first speaker 31A, the second speaker 31B, and the third speaker 31C output sounds AS1, AS2, and AS3 to be listened to, respectively.

[0044] For example, test tone output control unit 102 performs functions executed by DSP 23. During sound field correction processing, test tone output control unit 102 controls the output of first test tone TS1 from first speaker 31A, second test tone TS2 from second speaker 31B, and third test tone TS3 from third speaker 31C. The frequency bands of first test tone TS1, second test tone TS2, and third test tone TS3 are different, and the first test tone TS1, second test tone TS2, and third test tone TS3 are output simultaneously.

[0045] For example, during the execution of the sound field correction process, the test tone output control unit 102 controls the simultaneous output of a test tone group including the frequency bands of the first test tone TS1, the second test tone TS2, and the third test tone TS3. This increases the frequency component information used in the frequency analysis process, described later, to multiple frequencies, compared to a single frequency. Consequently, since noise-free frequencies can be used for sound field correction from among these multiple frequencies, the accuracy of the calculated impulse response after measurement can be improved.

[0046] The receiving unit 103, for example, uses the function performed by the communication I / F 15 as an example. The receiving unit 103 receives an acoustic signal St of a composite sound including a first test tone TS1, a second test tone TS2, and a third test tone TS3. In this embodiment, the receiving unit 103 receives the acoustic signal St from the remote control 41 via wireless communication. Specifically, the receiving unit 103 receives the acoustic signal St of the composite sound acquired by the microphone 45 provided in the remote control 41. It should be noted that the receiving unit 103 may also receive the acoustic signal St via wired communication.

[0047] The recording unit 104 is exemplified by a function executed by the memory 13. The recording unit 104 records the sound signal St received by the receiving unit 103 in a predetermined storage device (for example, the memory 13).

[0048] For example, the calculation unit 105 performs a frequency analysis process on the acoustic signal St recorded by the recording unit 104, analyzing the multiple frequency components contained in the acoustic signal St. Based on the results of the frequency analysis process, the calculation unit 105 calculates the arrival time t1 of the first test tone TS1 from the first speaker 31A to the microphone 45, the arrival time t3 of the second test tone TS2 from the second speaker 31B to the microphone 45, and the arrival time t2 of the third test tone TS3 from the third speaker 31C to the microphone 45. Furthermore, the calculation unit 105 calculates the time difference between the arrival times of the first test tone TS1 from the first speaker 31A to the microphone 45 and the arrival time t3 of the second test tone TS2 from the second speaker 31B to the microphone 45.

[0049] Furthermore, calculation unit 105 performs frequency analysis on the TSP signals acquired from the test tone group by multiplying the TSP signals by the corresponding inverse TSP signals. This allows the impulse responses of each speaker to be obtained. As a result, the arrival time differences between the speakers at microphone 45 can be calculated, thereby reducing the arrival time differences.

[0050] The memory 12 stores the calculation results of the time difference between the arrival times of the speakers at the listening positions calculated by the calculation unit 105. The memory 12 also stores the target amplitude of each speaker or the ratio of the target amplitudes of the speakers.

[0051] The audio decoder 21 converts the audio data into a digital signal in a format that can be output from the first speaker 31A, the second speaker 31B, and the third speaker 31C, and transmits the digital signal to the audio output control unit 101 .

[0052] The correction unit 106, for example, uses the function executed by the DSP 23. Based on the time difference from each speaker to the microphone 45 calculated by the calculation unit 105, it corrects the output timing of the sounds AS1, AS2, and AS3 outputted from the first speaker 31A, the second speaker 31B, and the third speaker 31C. Alternatively, it corrects the amplitude of the sounds AS1, AS2, and AS3 outputted from the speakers.

[0053] For example, if the arrival time t3 of the second test tone TS2 is later than the arrival time t1 of the first test tone TS1 by Δt1, correction unit 106 performs correction to delay the output timing of sound AS1 by Δt1 relative to the output timing of sound AS2. Furthermore, since multiple TSP signals are output from the test tone group, correction unit 106 can calculate the impulse response from TSP signals using other frequencies, even when noise is present, and calculate the arrival time from the speaker to microphone 45. This improves the accuracy of output timing correction.

[0054] With the above configuration, the test tone falls within a predetermined frequency band for each speaker. Therefore, even in the presence of a TSP signal containing noise, it is possible to calculate the arrival time differences of the individual sounds AS1, AS2, and AS3 at other frequencies, due to factors such as the positional relationship between the multiple speakers (in this embodiment, first speaker 31A, second speaker 31B, and third speaker 31C) and the listening position, and communication delays caused by wireless communication. As a result, the time differences can be accurately calculated and corrected using a single measurement.

[0055] Furthermore, correction can be performed based on the amplitude of each speaker so as to achieve the target amplitude.

[0056] FIG3 is a diagram illustrating an example of a method for calculating an impulse response according to an embodiment. As shown in FIG3 , the horizontal axis represents time t, and the vertical axis represents frequency. The impulse response can be calculated by receiving a TSP (Time Stretched Plus) signal of a fixed frequency band output from a single speaker and multiplying the received TSP signal by an inverse TSP signal.

[0057] Thus, compared to the case of calculating based on a single frequency, since the impulse response is calculated based on multiple frequencies, even when some noise is included, the impulse response can be calculated with a single measurement. Figure 3 shows the TSP signal output from a single speaker, and the above-mentioned impulse response calculation is performed for each speaker.

[0058] FIG4 is a diagram illustrating an example of a measurement signal according to an embodiment. Specifically, it shows TSP signals of different frequency bands simultaneously output from various speakers and received by the receiving unit 103. FIG4 shows a composite sound output by the first speaker 31A, the second speaker 31B, and the third speaker 31C. Specifically, FIG4(a) shows the composite sound output by the multiple speakers, with the vertical axis representing amplitude and the horizontal axis representing time t.

[0059] 4(b) shows frequency on the vertical axis and time t on the horizontal axis, illustrating the first output sound m1 of the first speaker 31A, the second output sound w1 of the second speaker 31B, and the third output sound a1 of the third speaker 31C. The first speaker 31A is exemplified as a main speaker that outputs high-frequency sound signals. The second speaker 31B is exemplified as a woofer that outputs low-frequency or mid-low-frequency sound signals. The third speaker 31C is exemplified as a tweeter that outputs high-frequency sound signals.

[0060] The first output sound m1 of the first speaker 31A can also be the first test tone TS1. An example of a frequency is a TSP signal between 3 [kHz] and 5 [kHz]. The second output sound w1 of the second speaker 31B can also be the second test tone TS2. An example of a frequency is a TSP signal between 50 [Hz] and 300 [Hz]. The third output sound a1 of the third speaker 31C can also be the third test tone TS3. An example of a frequency is a TSP signal between 8 [kHz] and 6 [kHz]. The impulse response is calculated by performing frequency analysis on the sound signal received by the receiving unit 103.

[0061] FIG5 illustrates an example of a TSP signal and an inverse TSP signal for one frequency band according to an embodiment. FIG5 illustrates the second output sound w1 from the second speaker 31B as an example. FIG5(a) illustrates the TSP signal for the second output sound w1 from the second speaker 31B. The vertical axis in the upper portion of FIG5(a) represents amplitude, and the horizontal axis represents time t. The vertical axis in the lower portion of FIG5(a) represents frequency, and the horizontal axis represents time t.

[0062] Figure 5(b) shows the inverse TSP signal of the TSP signal in Figure 5(a). The vertical axis in the upper portion of Figure 5(b) represents amplitude, and the horizontal axis represents time t. The vertical axis in the lower portion of Figure 5(b) represents frequency, and the horizontal axis represents time t. Specifically, the inverse TSP signal for the frequency band corresponding to the second output sound w1 of the fixed frequency band outputted from the second speaker 31B is shown.

[0063] Fig. 6 is a diagram showing an example of impulse response calculation results according to the embodiment. Fig. 6 shows impulse responses that can be obtained by multiplying the TSP signal, which is the recorded output audio signal, by an inverse TSP signal of a frequency band corresponding to each TSP signal.

[0064] The upper graph of Figure 6 shows the impulse response calculated based on the third output sound a1 outputted from the third speaker 31C. The impulse response of the third output sound a1 shows that its amplitude reaches its peak at time t2. The center graph of Figure 6 shows the impulse response calculated based on the first output sound m1 outputted from the first speaker 31A. The impulse response of the first output sound m1 shows that its amplitude reaches its peak at time t1. The lower graph of Figure 6 shows the impulse response calculated based on the second output sound w1 outputted from the second speaker 31B. The impulse response of the second output sound w1 shows that its amplitude reaches its peak at time t3.

[0065] As shown in FIG6 , the arrival time differences between the speakers at microphone 45 can be obtained based on the impulse response calculation results calculated by computing unit 105. FIG6 shows that t1 arrives first, followed by t2, which arrives earlier, and finally t3. Therefore, in the above example, the first output sound m1 outputted from first speaker 31A arrives first, followed by the third output sound a1 outputted from third speaker 31C, and finally, the second output sound w1 outputted from second speaker 31B.

[0066] Correction unit 106 delays the sound to match the speaker with the latest arrival time. Therefore, in this case, delay circuit 25A controls the output timings of the third output sound a1 (t2) from third speaker 31C and the first output sound m1 (t1) from first speaker 31A to match the arrival time of the second output sound w1 (t3) from second speaker 31B. This allows the difference in arrival time between speakers to be reduced by correcting the output timings of the speakers.

[0067] Specifically, the calculation unit 105 calculates the arrival time t1 of the first output sound m1 outputted from the first speaker 31A at the microphone 45, the arrival time t3 of the second output sound w1 outputted from the second speaker 31B at the microphone 45, and the arrival time t2 of the third output sound a1 outputted from the third speaker 31C at the microphone 45. The correction unit 106 then performs correction on the time difference Δt1 between the first output sound m1 of the first speaker 31A and the second output sound w1 of the second speaker 31B, thereby delaying the output timing of the first speaker 31A. Furthermore, the correction unit 106 performs correction on the time difference Δt2 between the third output sound a1 of the third speaker 31C and the second output sound w1 of the second speaker 31B, thereby delaying the output timing of the third speaker 31C.

[0068] Figure 7 is a flowchart illustrating an example of processing within the sound field correction device 5 according to an embodiment. As shown in Figure 7 , when the sound field correction process begins, the test tone output control unit 102 controls the output of a first test tone TS1 in a first frequency band from the first speaker 31A, controls the output of a second test tone TS2 in a second frequency band from the second speaker 31B, and controls the output of a third test tone TS3 in a third frequency band from the third speaker 31C. At this time, the first test tone TS1, the second test tone TS2, and the third test tone TS3 are output simultaneously. It should be noted that while these are test tones, they could also be test sounds or output sound signals. The first, second, and third frequency bands are distinct and non-overlapping frequency bands (step S1).

[0069] Next, the receiving unit 103 receives the composite sound signal St including the first test sound TS1, the second test sound TS2, and the third test sound TS3 acquired by the microphone 45 at the listening position. Then, the recording unit 104 receives and records the composite sound signal St from the receiving unit 103 (step S2).

[0070] Then, the calculation unit 105 calculates the start position of the measurement signal based on the designated frequency of the acoustic signal St recorded in the recording unit 104 (step S3 ).

[0071] Next, the calculation unit 105 performs frequency analysis by multiplying the start position offset of the acoustic signal St by the inverse TSP of different frequency bands. The impulse response corresponding to the output sound of each speaker is then obtained. Specifically, the impulse response corresponding to the TSP signal of each speaker is obtained by multiplying the TSP signal of each speaker by the corresponding inverse TSP signal (step S4).

[0072] Then, the calculation unit 105 calculates the maximum amplitude position and amplitude of the impulse response of each test tone (step S5 ).

[0073] The calculation unit 105 then calculates the time difference between the speakers reaching the listening position based on the calculated maximum amplitude positions. Furthermore, the magnitude of each amplitude is calculated. Specifically, the amplitude difference is calculated based on the target ratio of the speaker amplitudes stored in the memory 12 and the calculated ratio of the amplitudes of each speaker (step S6).

[0074] Finally, based on the calculated arrival time differences between the speakers at the listening position, the correction unit 106 controls the delay circuits 25A-25C so that the output timings of the sounds from the speakers are aligned. Furthermore, based on the calculated amplitude differences, the correction unit 106 controls the amplitude ratio of the speakers to approach a target ratio in order to optimize the amplitudes of the speakers (step S7).

[0075] According to the above embodiment, the output signal is not set to a single frequency, but rather to a fixed frequency band, and the impulse response is calculated in the frequency band. Therefore, even if some frequencies contain noise, the impulse response can be calculated at frequencies within the frequency band that do not contain noise. Therefore, by setting the frequency band to a fixed frequency band, the accuracy of the impulse response calculation in a single measurement can be improved compared to a single frequency.

[0076] Furthermore, by simultaneously outputting sound signals from each speaker, the maximum amplitude position of the impulse response can be calculated simultaneously. Therefore, the arrival time difference from each speaker to microphone 45 can be corrected with a single measurement. In other words, measurement and correction can be performed in a shorter time than with repeated measurements. Consequently, sound field correction processing can be performed quickly, providing a comfortable sound field.

[0077] Hereinafter, other embodiments will be described, and description of parts that exhibit the same or similar functions and effects as those of the first embodiment will be appropriately omitted.

[0078] Next, Figure 8 illustrates an example of a measurement method according to the second embodiment. Figure 8 illustrates a method for accurately calculating impulse responses by performing two measurements, for example, when two of three speakers have difficulty outputting TSP signals in different frequency bands.

[0079] FIG4 shows measurement signals of three TSP signals. FIG8 shows measurement signals of two TSP signals. FIG8 (a) shows measurement signals for measuring the first output sound m1 output from the first speaker 31A and the second output sound w1 output from the second speaker 31B. FIG8 (b) shows measurement signals for measuring the second output sound w1 output from the second speaker 31B and the fourth output sound a4 output from the fourth speaker 31D. It should be noted that the fourth speaker 31D only needs to have a different frequency band from the second speaker 31B. It should be noted that in the second embodiment, the third speaker 31C is omitted and the fourth speaker 31D is shown as an example instead. However, the third speaker 31C may also have a frequency band different from that of the second speaker 31B.

[0080] As an example, the first output sound m1 outputted from the first speaker 31A and the fourth output sound a4 outputted from the fourth speaker 31D are assumed to have the same frequency band. It should be noted that the frequency bands of the first output sound m1 and the fourth output sound a4 can also be different, as long as the frequency bands of the speakers measured simultaneously do not overlap. In other words, the frequency bands of the first speaker 31A and the second speaker 31B do not overlap, and the frequency bands of the fourth speaker 31D and the second speaker 31B do not overlap.

[0081] The vertical axis in the upper portion of Fig. 8(a) represents amplitude, and the horizontal axis represents time t. The vertical axis in the lower portion of Fig. 8(a) represents frequency, and the horizontal axis represents time t.

[0082] As shown in Figure 8(a), the first output sound m1 output from the first speaker 31A and the second output sound w1 output from the second speaker 31B are measured. Here, the frequency band of the first output sound m1 is set to 3 [kHz] to 5 [kHz], and the frequency band of the second output sound w1 is set to 50 [Hz] to 300 [Hz]. Then, by multiplying the measured TSP signal by the corresponding inverse TSP signal, the impulse response corresponding to each speaker can be calculated.

[0083] Then, the time difference Δt1 between the speakers is calculated based on the maximum amplitude positions of the first and second speakers 31A, 31B calculated from the impulse responses. Furthermore, the amplitude difference is calculated based on the target ratio of the amplitudes between the speakers and the calculated ratio of the amplitudes of the respective speakers.

[0084] Similarly, FIG8(b) shows measurement signals obtained by measuring the second output sound w1 output from the second speaker 31B and the fourth output sound a4 output from the fourth speaker 31D. The vertical axis in the upper portion of FIG8(b) represents amplitude, and the horizontal axis represents time t. The vertical axis in the lower portion of FIG8(b) represents frequency, and the horizontal axis represents time t.

[0085] As shown in Figure 8(b), the frequency band of the second output sound w1 is set to 50 [Hz] to 300 [Hz], and the frequency band of the fourth output sound a4 is set to 3 [kHz] to 5 [kHz]. Then, by multiplying the measured TSP signal by the corresponding inverse TSP signal, the impulse response corresponding to each speaker can be calculated.

[0086] Next, based on the maximum amplitude positions of second speaker 31B and fourth speaker 31D calculated from the impulse responses, the time difference between the speakers reaching the listening position is calculated. Furthermore, based on the target ratio of the amplitudes of the speakers and the calculated ratio of the amplitudes of each speaker, the amplitude difference is calculated.

[0087] In other words, the operation unit 105 calculates the time difference Δt1 between the first output sound m1 of the first frequency band output from the first speaker 31A and the second output sound w1 of the second frequency band different from the first frequency band output from the second speaker 31B, and further calculates the time difference Δt3 between the second output sound w1 and the fourth output sound a4 of the fourth frequency band different from the second frequency band output from the fourth speaker 31D, and calculates the time difference between the speakers arriving at the listening position based on the time difference Δt1 between the first output sound m1 and the second output sound w1 and the time difference Δt3 between the second output sound w1 and the fourth output sound a4.

[0088] Based on the arrival time differences between the speakers, calculated using the results of two separate calculations for first speaker 31A and second speaker 31B, and the results of two separate calculations for second speaker 31B and fourth speaker 31D, correction unit 106 controls at least one of delay circuits 25A-25C to align the output timings of the sounds from the respective speakers. Furthermore, based on the calculated amplitude differences between the speakers, control can be performed to bring the ratio of the amplitudes of the respective speakers closer to a target ratio, thereby optimizing the amplitudes of the respective speakers.

[0089] Furthermore, in the second embodiment, low-frequency and high-frequency combinations are used, such as the first speaker 31A and the second speaker 31B, and the second speaker 31B and the fourth speaker 31D. Specifically, TSP signals with separate frequency bands are measured. This reduces the likelihood of overlapping frequency bands in each measurement, allowing for more accurate impulse response calculation compared to combinations with similar frequency bands.

[0090] It should be noted that while the above embodiment uses internal speakers as an example for calibration, at least some of the speakers may be external. In this case, the time difference is calculated in the computing unit 105 of the sound field correction device 5, and the correction is performed in the delay circuit provided in the external speakers. Alternatively, the correction is performed in a delay circuit configured independently of the external speakers, and the result is output to the external speakers.

[0091] Furthermore, the number and type of speakers are not limited to the embodiments. For example, calibration between two internal speakers or calibration between two external speakers can also be performed using the same method as described above. Furthermore, even when there are four or more speakers, the same process as described in the embodiments can be performed sequentially to reduce the time difference between all speakers and optimize the volume balance of each speaker.

[0092] The program for realizing the functions of the sound field correction device 5 described above may be provided as a file that can be installed on a computer or as an executable file, recorded on a computer-readable storage medium such as a CD-ROM, floppy disk (FD), CD-R, or DVD (Digital Versatile Disk). Alternatively, the program may be stored on a computer connected to a network such as the Internet and downloaded via the network. Alternatively, the program may be provided or distributed via a network such as the Internet.

[0093] The embodiments of the present application have been described above. However, these embodiments are presented as examples and are not intended to limit the scope of the application. These new embodiments can be implemented in various other forms and can be omitted, replaced, or modified in various ways without departing from the scope of the invention. These embodiments and their variations are included within the scope and spirit of the invention and are included in the technical solutions described in the claims and their equivalents.

Claims

1. A sound field correction device that measures sounds output from a plurality of speakers at a predetermined listening position, wherein: The sound field correction device comprises: an output control unit configured to control the plurality of speakers so as to output sounds having different frequency bands from the plurality of speakers; a receiving unit for receiving the outputted sound information; a calculation unit that uses the received sound information to perform frequency analysis processing on each of the plurality of speakers and calculates a time difference between the sounds output by the plurality of speakers and the ... as well as A correction unit corrects output timings of the plurality of speakers based on the time difference.

2. The sound field correction device according to claim 1, wherein: The sound field correction device further includes a memory storing target amplitudes of the plurality of speakers. The calculation unit calculates the amplitude of the sound from the plurality of speakers.

3. The sound field correction device according to claim 2, wherein: The correction unit corrects the amplitude of at least one of the speakers based on the calculated amplitude.

4. The sound field correction device according to claim 1, wherein: The calculation unit calculates a time difference between a first sound in a first frequency band output by a first speaker and a second sound in a second frequency band different from the first frequency band output by a second speaker arriving at the listening position. The calculation unit further calculates a time difference between the second sound and a fourth sound in a fourth frequency band different from the second frequency band output from a fourth speaker reaching the listening position after a predetermined time has elapsed. The calculation unit calculates a time difference between the sounds output by the plurality of speakers and their arrival at a listening position based on an arrival time difference between the first sound and the second sound and an arrival time difference between the second sound and the fourth sound.

5. A sound field correction method, comprising measuring sounds output from a plurality of speakers at a predetermined listening position, wherein: The sound field correction method comprises the following steps: an output control step of controlling the plurality of speakers so that sounds of different frequency bands are output from the plurality of speakers; A step of receiving the outputted sound information; a step of performing frequency analysis processing on each of the plurality of speakers using information on the received sound, and calculating a time difference between when the sounds outputted by the plurality of speakers reach a listening position; as well as and correcting output timings of the plurality of speakers based on the time difference.

6. A nonvolatile storage medium storing a program for causing a sound field correction device that measures sounds output from a plurality of speakers at a predetermined listening position to execute the following processing: performing control so that the plurality of speakers output sounds having different frequency bands; receiving and processing the outputted sound information; performing frequency analysis processing on each of the plurality of speakers using the received sound information, and calculating the time difference between the sounds output by the plurality of speakers reaching the listening position; as well as A process of correcting the output timing of the speaker based on the time difference.

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