Acoustic characteristic correction device

• US 5,572,443 A
• Filed: 05/05/1994
• Issued: 11/05/1996
• Est. Priority Date: 05/11/1993
• Status: Expired due to Term

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Emoto, Naohiro, Ito, Tsugio
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): Assouad, Patrick J.
• Application Number:
  US08/238,510
• Time in Patent Office: 915 Days
• Field of Search: 364/550, 364/724.19, 381/103, 381/101, 359/173
• US Class Current: 702/103
• CPC Class Codes: H03G 5/165 Equalizers; Volume or gain control in limited frequency bands
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone
• CPC Class Codes: H04S 7/305 Electronic adaptation of stereophonic audio signals to reverberation of the listening space H04S7/301 takes precedence
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence
• CPC Class Codes: H04S 7/40 Visual indication of stereophonic sound image

Abstract

An acoustic characteristic correction device includes a section for setting a desired characteristic of a response characteristic in a reproduction system including a sound field, a section for outputting information of a measured characteristic of the response characteristic, a section for computing a correction characteristic for realizing the desired characteristic on the basis of the desired characteristic and the measured characteristic, and a section for imparting the computed correction characteristic to a sound signal to be reproduced. The device may further includes a display section for displaying the set desired characteristic, a section for controlling the level or frequency of the computed correction characteristic, a section for imparting a compensation characteristic to the correction characteristic. Results of measurement at plural points for plural measuring times may be stored and an average value of the results of measurement may be used as a measuring signal. In measuring a response characteristic by using a TSP signal, a convolution operator may be used commonly for time compression by an inverse filter characteristic and imparting of a correction characteristic.

Claims

1. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic display means for graphically displaying the set desired frequency-amplitude (gain) characteristic to assist the operation by the person;

measured frequency-amplitude (gain) characteristic input means for inputting information of a measured frequency-amplitude(gain) characteristic of the response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of tile desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced.

2. A device as defined in claim 1, further comprising measured frequency-amplitude (gain) characteristic display means for graphically displaying the measured frequency-amplitude (gain) characteristic.

3. A device as defined in claim 2, wherein said desired frequency-amplitude (gain) characteristic display means and said measured frequency-amplitude (gain) characteristic display means display the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic so that these characteristics are superposed one upon the other on a common axis of a graph.

4. A device as defined in claim 1, further comprising correction frequency-amplitude (gain) characteristic display means for graphically displaying the correction frequency-amplitude (gain) characteristic.

5. A device as defined in claim 1, wherein said desired frequency-amplitude (gain) characteristic setting means comprises:

a non-volatile memory for holding a plurality of the desired frequency-amplitude (gain) characteristics; and

desired frequency-amplitude,(gain) characteristic selection means for selectively reading out one of the desired frequency-amplitude (gain) characteristics held by the non-volatile memory on the basis of an operation by the operating person for setting the selected frequency-amplitude (gain) characteristic as the desired frequency-amplitude (gain) characteristic.

6. A deface as defined in claim 5, further comprising desired frequency-amplitude (gain) characteristic correction means for correcting the selected desired frequency-amplitude (gain) characteristic by operation of the operating person.

7. A device as defined in claim 6, further comprising corrected desired frequency-amplitude (gain) characteristic storage means for storing the desired frequency-amplitude (gain) characteristic which has been corrected by said desired frequency-amplitude (gain) characteristic correction means and wherein said desired frequency-amplitude (gain) characteristic selection means reads out, on the basis of an operation by the operating person, a desired one from among the corrected desired frequency-amplitude (gain) characteristic stored in said corrected desired frequency-amplitude (gain) characteristic storage means and the desired frequency-amplitude (gain) characteristics stored in said non-volatile memory for setting the selected frequency-amplitude (gain) characteristic as the desired frequency-amplitude (gain) characteristic.

8. A device as defined in claim 1, further comprising correction frequency-amplitude (gain) characteristic correction means for correcting, on the basis of an operation by the operating person for designating a correction frequency range, the frequency-amplitude (gain) characteristic outside of said range to a frequency-amplitude (gain) characteristic which is free from correction.

9. A device as defined in claim 1, further comprising:

measuring signal output means for outputting a measuring signal imparted with or without the correction frequency-amplitude (gain) characteristic on the basis of an operation by the operating person; and

response characteristic measuring means for obtaining information of the measured the frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring the response characteristic of the reproduction system including the sound field.

10. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced,

said response characteristic measuring means comprising;

measured result storing means for storing results of measurement at plural points for plural measuring times with respect to the same measuring signal; and

average frequency-amplitude (gain) characteristic computing means for computing an average value of the stored results of measurement to obtain the measured frequency-amplitude (gain) characteristic information.

11. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced,

said response characteristic measuring means comprising;

measured result storing means for storing results of measurement at plural points for plural measuring times with respect to the same measuring signal; and

average frequency-amplitude (gain) characteristic computing means for computing an average value of the stored results of measurement to obtain the measured frequency-amplitude (gain) characteristic information; and

measured result selection means for selecting, for the computation of the average value, one of the results of measurement at plural points for plural measuring times stored in said measured result storing means which satisfies a predetermined condition or which has been selected by an operation by the operating person.

12. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced,

said response characteristic measuring means comprising;

measured result storing means for storing results of measurement at plural points for plural measuring times with respect to the same measuring signal; and

average frequency-amplitude (gain) characteristic computing means for computing an average value of the stored results of measurement to obtain the measured frequency-amplitude (gain) characteristic information; and

weighting means for performing a predetermined weighting or a weighting set by an operation of the operating person with respect to the results of measurement at plural points for plural measuring times for outputting the weighted results of measurement for the computation of the average value.

13. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced;

said response characteristic measuring means comprising;

band average value computing means for computing an average value of result of measurement for each of frequency divided bands; and

interpolation means for computing values between average values for the respective divided bands by interpolation by treating these average values computed for the respective divided bands substantially as values at center frequency of the respective divided bands and thereby obtaining the measured frequency-amplitude (gain) characteristic information.

14. A device as defined in claim 13, wherein the respective divided bands are divided so that an end portion of each of the divided bands is overlapped with an end portion of an adjacent one of the divided bands.

15. A device as defined in claim 13, further comprising means for generating measuring signals which are divided in the frequency with a time lag to divide the frequency into bands.

16. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced;

said response characteristic measuring means comprising;

band average value computing means for computing an average value of result of measurement for each of frequency divided bands;

interpolation means for computing values between average values for the respective divided bands by interpolation by treating these average values computed for the respective divided bands substantially as values at center frequency of the respective divided bands and thereby obtaining the measured frequency-amplitude (gain) characteristic information; and

means for generating a time stretched pulse (TSP) as the measuring signal and means for analyzing an impulse response collected by the microphone in frequency to divide result of analysis into bands.

17. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a measuring signal;

response characteristic measuring means for obtaining information of a measured frequency-amplitude (gain) characteristic by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and thereby measuring a response characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operating person, a desired frequency-amplitude (gain) characteristic of the response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced,

said correction frequency-amplitude (gain) characteristic imparting means comprising;

band correction value computing means for computing, as a correction value for each of frequency divided bands, correction information of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of a measured frequency-amplitude (gain) characteristic computed for each of the frequency divided bands and a desired frequency-amplitude (gain) characteristic set for each of the frequency divided bands; and

interpolation means for computing values between the correction values for the respective divided bands by interpolation by treating these correction values computed for the respective divided bands substantially as values at center frequency of the respective divided bands and thereby obtaining the measured frequency-amplitude (gain) characteristic information.

18. An acoustic characteristic correction device comprising:

measuring signal output means for outputting a time stretched pulse (TSP) signal as a measuring signal;

inverse filter means for obtaining impulse response by inputting the output measuring signal which has been reproduced by a loudspeaker and collected by a microphone and performing time compression by a convolution operation with an inverse frequency-amplitude (gain) characteristic of the TSP signal;

frequency conversion means for converting the obtained impulse response in frequency to obtain information of a measured frequency-amplitude (gain) characteristic of a reproduction system including a sound field;

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic of the response characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced by a convolution operation,

said correction frequency-amplitude (gain) characteristic imparting means performing the convolution operation by utilizing a convolution operator which is commonly used for the convolution operation by said inverse filter means.

19. A device as defined in claim 18, wherein said convolution operator has the number of stages necessary for imparting the correction frequency-amplitude (gain) characteristic and has not the number of stages necessary for the time compression by said inverse filter frequency-amplitude (gain) characteristic and performs the time compression on timewise divided basis.

20. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for the setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

measured frequency-amplitude (gain) characteristic output means for outputting information of a measured frequency-amplitude (gain) characteristic of the response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced;

said correction frequency-amplitude (gain) characteristic imparting means comprising;

filter coefficient computing means for computing, as filter coefficients for a convolution operation corresponding to said correction frequency-amplitude (gain) characteristic, filter coefficients of a filter frequency-amplitude (gain) characteristic selected from among a plurality of filter frequency-amplitude (gain) characteristics including at least a linear phase filter according to which the entire range of the reproduction system becomes a linear phase frequency-amplitude (gain) characteristic and a minimum phase filter according to which the entire range of the reproduction system becomes a characteristic having no delay; and

a convolution operator for imparting said correction frequency-amplitude (gain) characteristic corresponding to the filter frequency-amplitude (gain) characteristic by performing a convolution operation using the filter coefficients of the selected filter frequency-amplitude (gain) characteristic with respect to the sound signal to be reproduced.

21. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for the setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

measured frequency-amplitude (gain) characteristic output means for outputting information of a measuring frequency-amplitude(gain) characteristic of the response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced;

said correction frequency-amplitude (gain) characteristic imparting means comprising;

filter coefficient computing means for computing, as filter coefficients for a convolution operation corresponding to said correction frequency-amplitude (gain) characteristic, filter coefficients of a filter frequency-amplitude (gain) characteristic selected from among a plurality of filter frequency-amplitude (gain) characteristics including at least a linear phase filter according to which the entire range of the reproduction system becomes a linear phase frequency-amplitude (gain) characteristic and a minimum phase filter according to which the entire range of the reproduction system becomes a characteristic having no delay; and

a convolution operator for imparting said correction frequency-amplitude (gain) characteristic corresponding to the filter frequency-amplitude (gain) characteristic by performing a convolution operation using the filter coefficients of the selected filter frequency-amplitude (gain) characteristic with respect to the sound signal to be reproduced,

wherein said filter coefficient computing means further has, as a selectable filter frequency-amplitude (gain) characteristic, a complex phase filter frequency-amplitude (gain) characteristic according to which a low frequency region in the reproduction system becomes a minimum phase frequency-amplitude (gain) characteristic, a high frequency region becomes a linear phase frequency-amplitude (gain) characteristic, and an intermediate frequency region becomes a frequency-amplitude (gain) characteristic which changes from the minimum phase frequency-amplitude (gain) characteristic to the linear phase frequency-amplitude (gain) characteristic.

22. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

measured frequency-amplitude (gain) characteristic output means for outputting information of a measured frequency-amplitude (gain) characteristic of the response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic;

correction frequency-amplitude (gain) characteristic level control means for controlling at least either an upper limit value or a lower limit value of the level of the computed correction frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic which has been controlled in the level to a sound signal to be reproduced.

23. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

measured frequency-amplitude (gain) characteristic output means for outputting information of a measured frequency-amplitude (gain) characteristic of the response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic;

correction frequency-amplitude (gain) characteristic frequency control means for controlling at least either an upper limit value of a lower limit value of the frequency range of the computed correction frequency-amplitude (gain) characteristic; and

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic which has been controlled in the frequency range to a sound signal to be reproduced.

24. An acoustic characteristic correction device comprising:

desired frequency-amplitude (gain) characteristic setting means for setting, on the basis of an operation by an operating person, a desired frequency-amplitude (gain) characteristic of a response characteristic in a reproduction system including a sound field;

measured frequency-amplitude (gain) characteristic output means for outputting information of a measured frequency-amplitude (gain) characteristic of a response characteristic of the reproduction system including the sound field;

correction frequency-amplitude (gain) characteristic computing means for computing a correction frequency-amplitude (gain) characteristic for realizing the desired frequency-amplitude (gain) characteristic on the basis of the desired frequency-amplitude (gain) characteristic and the measured frequency-amplitude (gain) characteristic;

correction frequency-amplitude (gain) characteristic imparting means for imparting the computed correction frequency-amplitude (gain) characteristic to a sound signal to be reproduced;

reverberation time frequency characteristic/average sound absorption rate frequency characteristic output means for outputting information of a reverberation time frequency characteristic or an average sound absorption rate frequency characteristic of said sound field; and

characteristic compensation means for imparting, on the basis of the information of the reverberation time frequency characteristic or the average sound absorption rate frequency characteristic, a compensation characteristic to the correction frequency-amplitude (gain) characteristic so as to relatively increase the level of the correction frequency-amplitude (gain) characteristic with respect to a frequency for which the reverberation time is long or for which the average sound absorption rate is low.