US 9,812,114 B2
Systems and methods for controlling adaptive noise control gain
Jeffrey D. Alderson, Austin, TX (US); Jon D. Hendrix, Wimberley, TX (US); Sang-Ik Terry Cho, Austin, TX (US); Chin Huang Yong, Austin, TX (US); and John L. Melanson, Austin, TX (US)
Assigned to Cirrus Logic, Inc., Austin, TX (US)
Filed by Cirrus Logic International Semiconductor Ltd., Edinburgh (GB)
Filed on Mar. 2, 2016, as Appl. No. 15/58,866.
Prior Publication US 2017/0256248 A1, Sep. 7, 2017
Int. Cl. A61F 11/06 (2006.01); G10K 11/16 (2006.01); G10K 11/178 (2006.01)
CPC G10K 11/178 (2013.01) [G10K 11/1784 (2013.01); G10K 11/1786 (2013.01); G10K 2210/1081 (2013.01); G10K 2210/3014 (2013.01); G10K 2210/3028 (2013.01); G10K 2210/3056 (2013.01)] 34 Claims
OG exemplary drawing
 
1. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
an output for providing a signal to a transducer including both a source audio signal for playback to a listener and a scaled anti-noise signal for countering the effect of ambient audio sounds in an acoustic output of the transducer;
a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds;
an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and
a processing circuit comprising:
an adaptive filter having a response that generates an unscaled anti-noise signal from the reference microphone signal to reduce the presence of the ambient audio sounds heard by the listener;
a scaling portion that generates the scaled anti-noise signal by applying a scaling factor to the anti-noise signal;
a coefficient control block that shapes the response of the adaptive filter in conformity with the reference microphone signal and the error microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone signal; and
a biasing portion configured to further adjust the response of the adaptive filter independent of the source audio signal by altering an input to the coefficient control block of the adaptive filter to compensate for the scaling factor.