Measurement method and device

Abstract

To provide a measurement method and a measurement device that prevent an increase in the number of measurements even when the number of speakers increases.SOLUTION: A measurement method includes: generating a plurality of second measurement signals that are obtained by arranging a plurality of first measurement signals corresponding to a plurality of speakers, respectively, at each different time zone on a time axis; generating a plurality of third measurement signals that are obtained by copying a part of a rear end of each of the plurality of second measurement signals to add to a leading end of each of the plurality of second measurement signals; outputting each sound relating to the plurality of third measurement signals from the plurality of speakers; collecting sound including the plurality of third measurement signals by a microphone; and calculating a plurality of impulse responses corresponding to the plurality of first measurement signals, based on the collected sound signals collected by the microphone and the third measurement signals.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method and device for measuring an impulse response. [Background technology]

[0002] Patent Document 1 describes a method of measuring the acoustic characteristics of each of a plurality of speakers by outputting a test sound from each of the speakers. The measurement results are used to adjust, for example, the frequency characteristics, output timing, or volume level. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 173131 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional measurement method, a test sound is output from each of a plurality of speakers in turn, so as the number of speakers increases, the number of measurements increases and the measurement time increases.

[0005] Therefore, an object of one embodiment of the present invention is to provide a measurement method and a measurement device that prevent an increase in the number of measurements even when the number of speakers is increased. [Means for solving the problem]

[0006] A measurement method according to one embodiment of the present invention generates a plurality of second measurement signals by arranging a plurality of first measurement signals corresponding to each of the plurality of speakers at different time periods on a time axis, generates a plurality of third measurement signals by copying a portion of the rear end of each of the plurality of second measurement signals and adding it to the front end of each of the plurality of second measurement signals, outputs sounds related to the third measurement signals from each of the plurality of speakers, collects sounds including the plurality of third measurement signals with a microphone, and calculates a plurality of impulse responses corresponding to the plurality of first measurement signals based on the collected signals collected by the microphone and the third measurement signals. Effect of the Invention

[0007] According to one embodiment of the present invention, even if the number of speakers increases, an increase in the number of measurements can be prevented. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram showing a configuration of a measurement system. [Diagram 2] 1 is a block diagram showing a configuration of an audio device 10. FIG. [Diagram 3] 4 is a flowchart showing the operation of the audio device 10. [Figure 4] FIG. 4(A) is a diagram showing the amplitude waveform on the time axis of the test sound corresponding to speaker 11, FIG. 4(B) is a diagram showing the amplitude waveform on the time axis of the test sound corresponding to speaker 12, FIG. 4(C) is a diagram showing the amplitude waveform on the time axis of the test sound corresponding to speaker 13, and FIG. 4(D) is a diagram showing the amplitude waveform on the time axis of the test sound corresponding to speaker 18. [Diagram 5] Figure 5(A) is a diagram showing the amplitude waveform on the time axis of a measurement signal corresponding to speaker 11, Figure 5(B) is a diagram showing the amplitude waveform on the time axis of a measurement signal corresponding to speaker 12, Figure 5(C) is a diagram showing the amplitude waveform on the time axis of a measurement signal corresponding to speaker 13, and Figure 5(D) is a diagram showing the amplitude waveform on the time axis of a measurement signal corresponding to speaker 18. [Figure 6]Figure 6(A) is the third measurement signal corresponding to speaker 11, Figure 6(B) is the third measurement signal corresponding to speaker 12, Figure 6(C) is the third measurement signal corresponding to speaker 13, and Figure 6(D) is the third measurement signal corresponding to speaker 18. [Figure 7] 7A shows a signal picked up by the microphone 20, and FIG. 7B shows a signal picked up by the microphone 20 after 131072 samples have been extracted from the signal. [Figure 8] FIG. 2 is a diagram showing an amplitude waveform on the time axis of an impulse response H(t). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1 is a block diagram showing the configuration of a measurement system 1 according to one embodiment of the present invention. Measurement system 1 includes an audio device 10, a microphone 20, and multiple speakers 11-18. Audio device 10 is connected to microphone 20 and multiple speakers 11-18 via audio cables. However, audio device 10 may also be connected to microphone 20 and multiple speakers 11-18 via wireless communication.

[0010] Audio device 10 receives an audio signal from a content reproduction device such as a television or a player. Audio device 10 may also receive content data from a server or the like via the Internet. When audio device 10 receives the content data, it decodes the content data to extract the audio signal.

[0011] Audio device 10 outputs sound signals to speakers 11 to 18. Audio device 10 performs signal processing on the sound signals to be supplied to each speaker in accordance with the acoustic characteristics of each of speakers 11 to 18. The signal processing includes, for example, adjustment of frequency characteristics, adjustment of output timing, or adjustment of volume level.

[0012] 2 is a block diagram showing the configuration of audio device 10. Audio device 10 includes a display 101, a user interface (I / F) 102, a CPU 103, a flash memory 104, a RAM 105, an audio I / O 106, and a communication interface (I / F) 107.

[0013] Display 101 is made up of multiple LEDs and displays various states of audio device 10, such as a power-on state. User I / F 102 includes, for example, a power button and a measurement start button. When the user presses the measurement start button, audio device 10 executes the measurement method of this embodiment. Note that the user may issue a measurement start instruction from a remote control for audio device 10, or an application program installed in an information processing device, such as a smartphone, connected to audio device 10.

[0014] CPU 103 reads out a program stored in flash memory 104, which is a storage medium, into RAM 105 to realize a predetermined function. For example, CPU 103 decodes content data received from communication I / F 107 and extracts an audio signal. CPU 103 outputs the audio signal to speakers 11 to 18 via audio I / O 106.

[0015] Moreover, CPU 103 functions as a measurement unit. CPU 103 outputs a measurement signal corresponding to a measurement sound to speakers 11 to 18. CPU 103 receives a pickup signal related to a sound picked up by microphone 20 via audio I / O 106. CPU 103 measures the acoustic characteristics of speakers 11 to 18 based on the measurement signal output to speakers 11 to 18 and the pickup signal received by microphone 20.

[0016] Fig. 3 is a flowchart showing the operation of audio device 10. Audio device 10 performs the operation shown in Fig. 3 when, for example, an instruction to start measurement is received from a user. First, audio device 10 generates a test sound (S11). Fig. 4(A) is a diagram showing an amplitude waveform of the test sound on the time axis. The test sound is, for example, pink noise. However, the test sound is not limited to pink noise. The test sound may be white noise. Alternatively, the test sound may be any kind of sound, such as M-sequence pseudo-noise or a sweep wave.

[0017] The duration of the measurement sound is determined by the duration of the acoustic characteristic to be measured and the number of speakers (8 in this embodiment). For example, if the sampling frequency is 48 kHz and the number of samples required to correspond to the duration of the acoustic characteristic is 16384 samples, the number of samples required to correspond to the duration of the measurement sound is 16384 x 8 = 131072 samples.

[0018] Next, audio device 10 shifts a portion of the measurement sound to generate a measurement signal for each speaker (S12). For example, audio device 10 shifts a portion of the rear end of the measurement sound shown in Fig. 4(A) to the front end to generate a measurement sound as shown in Fig. 4(B). The number of samples shifted corresponds to the time length of the acoustic characteristic, and is, for example, 16384 samples.

[0019] Figures 5(A) to 5(D) are diagrams showing the measurement signals for each speaker. Figure 5(A) is the measurement signal corresponding to speaker 11. The measurement signal shown in Figure 5(A) is the same as the measurement sound shown in Figure 4(A), and is the same as the pink noise which is the measurement sound generated in the process of S11.

[0020] Fig. 5(B) shows a measurement signal corresponding to the speaker 12. The measurement signal in Fig. 5(B) is the same signal as the time-axis waveform shown in Fig. 4(B). The measurement signal in Fig. 5(B) is a time-axis waveform in which component H, which is a part (16384 samples) of the rear end of the pink noise generated in the processing of S11, is moved to the front end.

[0021] Fig. 5(C) is a measurement signal corresponding to speaker 13. The measurement signal in Fig. 5(C) is a time-axis waveform in which component G, which is a part (16384 samples) at the rear end of the measurement signal corresponding to speaker 12 shown in Fig. 5(B), is moved to the front end.

[0022] Fig. 5(D) is a measurement signal corresponding to speaker 18. The measurement signal in Fig. 5(D) is a time-axis waveform in which component B, which is a portion (16384 samples) at the rear end of the measurement signal corresponding to speaker 17, is moved to the front end.

[0023] In this way, audio device 10 moves some of the components at the rear end of the measurement signal to the front end to generate a measurement signal for each speaker. These components A to H each correspond to the first measurement signal of the present invention. The measurement signal corresponding to each speaker arranges components A to H in different time periods on the time axis. The measurement signal corresponding to each speaker corresponds to the second measurement signal of the present invention.

[0024] Next, audio device 10 generates a third test signal by copying a part of the rear end of the second test signal for each speaker and adding it to the front end (S13). Figures 6(A) to 6(D) are diagrams showing the third test signal for each speaker.

[0025] Fig. 6(A) shows the third measurement signal corresponding to the speaker 11. The third measurement signal corresponding to the speaker 11 is a signal in which a part of the rear end component H of the second measurement signal shown in Fig. 5(A) is copied and added to the front end.

[0026] Fig. 6(B) shows a third measurement signal corresponding to the speaker 12. The third measurement signal corresponding to the speaker 12 is a signal obtained by copying a part of the component G at the rear end of the second measurement signal shown in Fig. 5(B) and adding it to the front end.

[0027] Fig. 6(C) shows a third measurement signal corresponding to the speaker 13. The third measurement signal corresponding to the speaker 13 is a signal in which a part of the rear end component F of the second measurement signal shown in Fig. 5(C) is copied and added to the front end.

[0028] Fig. 6(D) shows a third measurement signal corresponding to the speaker 18. The third measurement signal corresponding to the speaker 18 is a signal in which a part of component A at the rear end of the second measurement signal shown in Fig. 5(D) is copied and added to the front end.

[0029] In this way, audio device 10 generates the third test signal for each speaker by copying a portion (16384 samples) of the components at the rear end of the second test signal and moving it to the front end. This type of third test signal is the same as the second test signal in which the rear end signal wraps around to the front end. In other words, the third test signal is a one-cycle signal, but is synonymous with the second and subsequent cycles of a periodic signal.

[0030] Next, audio device 10 starts measurement (S14). Audio device 10 simultaneously outputs third test signals to speakers 11 to 18. Simultaneously with the output of the third test signals, audio device 10 starts collecting (recording) sound using microphone 20.

[0031] Then, audio device 10 measures an impulse response corresponding to the acoustic characteristics of each speaker based on the sound signal picked up by microphone 20 and the measurement sound (pink noise) generated in S11 (S15).

[0032] Fig. 7(A) is an amplitude waveform on the time axis of the signal picked up by the microphone 20. As shown in Fig. 7(A) and Fig. 7(B), the audio device 10 removes a portion (16384 samples) at the beginning from the signal picked up by the microphone 20, and extracts a signal of 131072 samples that corresponds to the time length of the measurement sound generated in S11.

[0033] For example, audio device 10 obtains an impulse response by convolving the inverse function of the measurement sound generated in S11 with the collected sound signal. More specifically, audio device 10 performs a Fourier transform on the measurement sound X(t) generated in S11 to obtain a frequency signal X(ω), and performs a Fourier transform on the collected sound signal Y(t) shown in Fig. 7(B) to obtain a frequency signal Y(ω). Then, the frequency signal H(ω) of the impulse response H(t) is expressed by the following formula (1) based on the cross-spectral method.

[0034] H(ω)=(conj(Y(ω))·X(ω)) / (conj(X(ω))·X(ω)) ···Equation (1) Here, conj(X(ω)) represents the complex conjugate of X(ω), and conj(Y(ω)) represents the complex conjugate of Y(ω).

[0035] The audio device 10 can obtain the impulse response H(t) by performing an inverse Fourier transform on the frequency signal H(ω) obtained by the above equation (1).

[0036] FIG. 8 is a diagram showing an amplitude waveform on the time axis of the impulse response H(t). The sound signal collected by the microphone 20 includes a plurality of third measurement signals output simultaneously from the speakers 11 to 18. As shown in FIG. 5(A) to FIG. 5(D), the plurality of third measurement signals are arranged with components A to H at different time periods on the time axis. For example, the third measurement signal output from the speaker 11, excluding the first 16384 samples, is the same as the measurement sound generated in S11. Therefore, as shown in FIG. 8, the first 16384 samples of the impulse response H(t) correspond to the impulse response of the third measurement signal output from the speaker 11.

[0037] The third measurement signal output from the speaker 12, excluding the first 16,384 samples, is a signal obtained by shifting the measurement sound generated in S11 in time by 16,384 samples. Therefore, the impulse response of the third measurement signal output from the speaker 12 appears at a position shifted 16,384 samples backward. Similarly, the impulse responses of the third measurement signal output from each speaker appear at different time periods on the time axis.

[0038] This allows audio device 10 to obtain the acoustic characteristics of each of speakers 11 to 18 by extracting each of 16384 samples of impulse response H(t).

[0039] In this way, the measurement method shown in this embodiment can obtain the impulse responses (acoustic characteristics) of multiple speakers in one measurement. Although the number of speakers in this embodiment is eight, the number of speakers may be greater or less. The measurement method shown in this embodiment can obtain the impulse responses (acoustic characteristics) of multiple speakers in one measurement, regardless of the number of speakers. Therefore, the measurement method shown in this embodiment can prevent an increase in the number of measurements even if the number of speakers increases.

[0040] The frequency signal H(ω) of the impulse response shown in the above formula (1) is based on the principle of circular convolution, in which the impulse response H(t) on the time axis is repeated periodically. Therefore, the principle of circular convolution cannot be satisfied if the measurement signal (measurement sound output from the speaker) is a signal with one period. However, in this embodiment, the third measurement signal output from each speaker can be treated in the same way as a signal from the second period onwards of a periodic signal, with the signal at the rear end of the second measurement signal wrapping around to the front end. Therefore, the measurement method of this embodiment satisfies the principle of circular convolution, and the frequency signal H(ω) of the impulse response can be correctly obtained by the above formula (1).

[0041] It is not essential to remove the first 16384 samples of the signal picked up by the microphone 20. In this case, however, since the first signal contains an extra signal of 16384 samples, all impulse responses corresponding to the acoustic characteristics of each speaker among the impulse responses H(t) are shifted back by 16384 samples. In this case, the audio device 10 only needs to extract a signal of 1347456 samples, which is 16384 samples longer than the duration of the measurement sound generated in S11, from the signal picked up by the microphone 20, and obtain the impulse response.

[0042] The time length of each of the multiple first measurement signals (components A to H) may be the same as the time length of the acoustic characteristic to be measured, or may be longer than the time length of the acoustic characteristic. For example, when the audio device 10 and the speakers 11 to 18 are connected by wireless communication, the timing at which the speakers 11 to 18 output the third measurement signal may differ. When the time length of each of the multiple first measurement signals (components A to H) is the same as the time length of the acoustic characteristic, if the timing at which the third measurement signal is output differs, the impulse responses of the impulse response H(t) corresponding to each speaker overlap on the time axis. However, when the time length of each of the multiple first measurement signals (components A to H) is longer than the time length of the acoustic characteristic, the impulse responses of each speaker do not overlap on the time axis in the impulse response H(t), and the impulse responses of each speaker can be extracted. Furthermore, when the time length of each of the multiple first measurement signals (components A to H) is longer than the time length of the acoustic characteristics, the impulse responses of each speaker can be extracted without overlapping on the time axis between the impulse responses of each speaker even if the third measurement signals are not output simultaneously from all of the speakers 11 to 18.

[0043] In the above embodiment, audio device 10 generates a pink noise measurement sound (fourth measurement signal) whose time length is based on the time length of the acoustic characteristics and the number of speakers, and generates the second measurement signal by moving components A to H of the pink noise, which is the fourth measurement signal, corresponding to the first measurement signal of each speaker to the respective time periods. However, audio device 10 may generate the first measurement signal for each speaker individually, and generate the second measurement signal by arranging the generated first measurement signals on the time axis. In this case as well, audio device 10 generates the second measurement signal by arranging the multiple first measurement signals in different time periods on the time axis.

[0044] Finally, the description of the present embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, not by the above-mentioned embodiment. Furthermore, the scope of the present invention includes a scope equivalent to the claims. For example, the audio device, the microphone, and the speaker may be built into one housing. In this case, the audio device may output a sound related to the measurement signal from the built-in speaker and collect the sound related to the measurement signal with the built-in microphone. Moreover, the number of microphones is not limited to one, and may be multiple. [Explanation of symbols]

[0045] 1. Measurement system 10. Audio equipment 11,12,13,14,15,16,17,18…Speakers 20…Mike 101...Indicator 102...User I / F 103…CPU 104...Flash memory 105…RAM 106…Audio I / O 107…Communication I / F

Claims

1. A method for measuring acoustic characteristics of a plurality of speakers, comprising: generating a plurality of first measurement signals corresponding to the plurality of speakers individually for each speaker, and generating a plurality of second measurement signals by arranging the generated plurality of first measurement signals at different time periods on a time axis; generating a plurality of third measurement signals by copying a portion of the rear end of each of the plurality of second measurement signals and adding the copied portion to the front end of each of the plurality of second measurement signals; outputting sounds related to the third measurement signal from each of the plurality of speakers; A microphone is used to collect a sound including the third measurement signals; calculating a plurality of impulse responses corresponding to the plurality of first measurement signals based on a sound signal collected by the microphone and the second measurement signal; Measurement method.

2. a time length of each of the plurality of first measurement signals corresponds to a time length of the acoustic characteristic; The measurement method according to claim 1.

3. A time length of each of the plurality of first measurement signals is longer than a time length of the acoustic characteristic. The measurement method according to claim 1.

4. generating a fourth measurement signal, and shifting components of the fourth measurement signal corresponding to the first measurement signal of each speaker to respective time periods to generate the second measurement signal; The measurement method according to any one of claims 1 to 3.

5. the plurality of first measurement signals include pink noise; The measurement method according to any one of claims 1 to 4.

6. the plurality of first measurement signals include white noise; The measurement method according to any one of claims 1 to 5.

7. The impulse response is calculated based on a cross-spectral method. The measurement method according to any one of claims 1 to 6.

8. A measurement device for measuring acoustic characteristics of a plurality of speakers, comprising: A microphone and a measuring unit are provided, The measurement unit includes: generating a plurality of first measurement signals corresponding to the plurality of speakers individually for each speaker, and generating a plurality of second measurement signals by arranging the generated plurality of first measurement signals at different time periods on a time axis; generating a plurality of third measurement signals by copying a portion of the rear end of each of the plurality of second measurement signals and adding the copied portion to the front end of each of the plurality of second measurement signals; outputting sounds related to the third measurement signal from each of the plurality of speakers; A sound including the plurality of third measurement signals is picked up by the microphone; calculating a plurality of impulse responses corresponding to the plurality of first measurement signals based on a sound signal collected by the microphone and the second measurement signal; Measuring equipment.

9. a time length of each of the plurality of first measurement signals corresponds to a time length of the acoustic characteristic; 9. The measuring device according to claim 8.

10. A time length of each of the plurality of first measurement signals is longer than a time length of the acoustic characteristic.

9. The measuring device according to claim 8.

11. The measurement unit generates a fourth measurement signal, and generates the second measurement signal by moving a component of the fourth measurement signal corresponding to the first measurement signal of each speaker to a respective time period. The measuring device according to any one of claims 8 to 10.

12. the plurality of first measurement signals include pink noise; 12. The measuring device according to claim 8.

13. the plurality of first measurement signals include white noise; 13. The measuring device according to any one of claims 8 to 12.

14. The measurement unit calculates the impulse response based on a cross-spectral method.

14. The measuring device according to any one of claims 8 to 13.

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