Multipass parametric or graphic EQ fitting

• US 7,664,276 B2
• Filed: 02/15/2005
• Issued: 02/16/2010
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: McKee Cooper, Joel C.
• Primary Examiner(s): Mei; Xu
• Application Number:
  US11/057,367
• Publication Number:
  US 20060062405A1
• Time in Patent Office: 1,827 Days
• Field of Search: 381/56, 381/58, 381/103, 333/28.R, 375229-231
• US Class Current: 381/103
• CPC Class Codes: G01S 11/14 using ultrasonic, sonic, or infrasonic waves
• 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: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

Multiple passes are executed in the setup of an equalizer, and modification of the equalization is performed after each pass of an analysis phase. After an initial pass, the equalization is adjusted, based upon the location of peaks and valleys in the system response. This initial adjustment of equalization may tend to flatten most of the peaks and valleys to produce the desired uniform linear response. Inexact application of equalization corrections may introduce other artifacts into the system response and/or may not sufficiently normalize equalization. A second pass is then performed to measure the system response using the new equalization settings. The new peaks and valleys are measured, and the equalization adjusted to try to flatten response further. A proximity range may be applied to each pass, to reduce the likelihood that adjustment of one equalizer coefficient will create artifacts in the resulting system response.

Claims

1. A method for adjusting an equalizer, comprising:

(a) generating an audio test signal,

(b) equalizing the audio test signal using an equalizer having a plurality of adjustable equalizer coefficients,

(c) receiving the audio test signal output from a speaker to a signal detector,

(d) analyzing the received audio signal to determine system response and detect peaks and valleys in the system response;

(e) adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response;

repeating steps (a)-(d) using the equalizer coefficients adjusted in step (e), and

adjusting remaining equalizer coefficients corresponding to corresponding peaks or valleys in the system response.

2. The method of claim 1, wherein the audio test signal comprises a digital audio test signal, and the equalization is performed in a digital signal decoder, the method further includes:

converting the digital audio test signal to an analog audio test signal, and

outputting the audio test signal to a room through a speaker, and

converting the audio test signal from the signal detector into a digital audio signal.

3. A method of adjusting an equalizer, comprising:

(a) generating an audio test signal,

(b) equalizing the audio test signal using an equalizer having a plurality of adjustable equalizer coefficients,

(c) receiving the audio test signal output from a speaker to a signal detector,

(d) analyzing the received audio signal to determine system response and detect peaks and valleys in the system response; and

(e) adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response comprises;

(f) adjusting an equalizer corresponding to a first peak or valley,

(g) applying a proximity range to the first peak or valley,

(h) discarding a subsequent peak or valley within the proximity range, and repeating steps (f) through (h) for a next peak or valley outside the proximity range.

4. The method of claim 3, wherein the audio test signal comprises a digital audio test signal, and the equalization is performed in a digital signal decoder, the method further includes:

converting the digital audio test signal to an analog audio test signal, and

outputting the audio test signal to a room through a speaker, and

converting the audio test signal from the signal detector into a digital audio signal.

5. A method for adjusting an equalizer, comprising:

(a) generating an audio test signal,

(b) equalizing the audio test signal using an equalizer having a plurality of adjustable equalizer coefficients,

(c) receiving the audio test signal output from a speaker to a signal detector,

(d) analyzing the received audio signal to determine system response and detect peaks and valleys in the system response; and

(e) adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

repeating steps (a) through (f) to remove artifacts created in the system response due to a previous adjustment of the equalizer coefficients.

6. The method of claim 5, wherein the audio test signal comprises a digital audio test signal, and the equalization is performed in a digital signal decoder, the method further includes:

converting the digital audio test signal to an analog audio test signal, and

outputting the audio test signal to a room through a speaker, and

converting the audio test signal from the signal detector into a digital audio signal.

7. An audio equalizer, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

an analyzer, coupled to receive the audio test signal as output from a speaker to a signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer analyzes a subsequent test signal equalized by the equalizer using adjusted equalizer coefficients and adjusts remaining equalizer coefficients corresponding to remaining corresponding peaks or valleys in the system response.

8. The audio equalizer of claim 7, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.

9. The audio equalizer of claim 8, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.

10. An audio equalizer, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

an analyzer, coupled to receive the audio test signal output from a speaker to a signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer adjusts an equalizer coefficient corresponding to a first peak or valley, applies a proximity range to the first peak or valley, discards subsequent peaks or valleys within the proximity range, and adjusts an equalizer coefficient for a next peak or valley outside the proximity range.

11. An audio equalizer, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

an analyzer, coupled to receive the audio test signal as output from a speaker to a signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer analyzes a subsequent test signal equalized by the equalizer using adjusted equalizer coefficients and adjusts equalizer coefficients to remove artifacts created in the system response due to a previous adjustment of the equalizer coefficients.

12. The audio equalizer of claim 11, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.

13. A home theater system, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

at least one speaker, placed in a room for generating sound from the audio test signal;

at least one signal detector, placed in the room, for receiving sound from the speaker; and

an analyzer, coupled to receive the audio test signal as output from the speaker to the signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer analyzes a subsequent test signal equalized by the equalizer using adjusted equalizer coefficients and adjusts remaining equalizer coefficients corresponding to remaining corresponding peaks or valleys in the system response.

14. The home theater system of claim 13, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.

15. A home theater, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

at least one speaker, placed in a room, for generating sound from the audio test signal;

at least one signal detector, placed in the room, for receiving sound from the speaker; and

an analyzer, coupled to receive the audio test signal as output from the speaker to the signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer adjusts an equalizer coefficient corresponding to a first peak or valley, applies a proximity range to the first peak or valley, discards subsequent peaks or valleys within the proximity range, and adjusts an equalizer coefficient for a next peak or valley outside the proximity range.

16. The home theater system of claim 15, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.

17. A home theater system, comprising:

an audio test signal generator for generating an audio test signal;

an equalizer having a plurality of adjustable equalizer coefficients for equalizing the audio test signal;

at least one speaker, placed in a room, for generating sound from the audio test signal;

at least one signal detector, placed in the room, for receiving sound from the speaker; and

an analyzer, coupled to receive the audio test signal as output from the speaker to the signal detector, for analyzing the received audio signal to determine system response and detect peaks and valleys in the system response, and adjusting one or more of the plurality of adjustable equalizer coefficients of the equalizer corresponding to one or more corresponding peaks and valleys in the system response,

wherein the analyzer analyzes a subsequent test signal equalized by the equalizer using adjusted equalizer coefficients and adjusts equalizer coefficients to remove artifacts created in the system response due to a previous adjustment of the equalizer coefficients.

18. The home theater system of claim 17, wherein the audio test signal comprises a digital audio test signal, and the equalizer comprises a portion of a digital signal decoder,

wherein the digital audio test signal is converted to an analog audio test signal, and output to a room through a speaker, and the audio test signal from the signal detector is converted into a digital audio signal before being fed to the analyzer.