US 10,893,363 B2
Self-equalizing loudspeaker system
Sylvain J. Choisel, Palo Alto, CA (US); and Dane R. Bush, Mountain View, CA (US)
Assigned to APPLE INC., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Sep. 26, 2019, as Appl. No. 16/584,065.
Claims priority of provisional application 62/739,051, filed on Sep. 28, 2018.
Prior Publication US 2020/0107121 A1, Apr. 2, 2020
Int. Cl. H04R 3/04 (2006.01); H04R 29/00 (2006.01); H04S 7/00 (2006.01); H04R 3/12 (2006.01)
CPC H04R 3/04 (2013.01) [H04R 3/12 (2013.01); H04R 29/002 (2013.01); H04S 7/301 (2013.01); H04S 7/307 (2013.01); H04R 2430/01 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A digital audio equalization system comprising:
a processor and non-transitory memory having stored therein instructions that when executed by the processor
compute an impulse response between i) an audio signal that is being output as sound by a loudspeaker that is integrated in a loudspeaker enclosure, and ii) a microphone signal from a microphone that is recording the output by the loudspeaker and that is also integrated in the loudspeaker enclosure,
analyze the impulse response to extract a reverberation level at each of a plurality of frequency bands, to yield a reverberation spectrum,
estimate sound power spectrum at a listening distance from the loudspeaker, based on the reverberation spectrum, and
determine an equalization filter based on i) the estimated sound power spectrum and ii) a desired frequency response at the listening distance, wherein the equalization filter is to filter a user audio program signal for output by the loudspeaker.