Apple Inc.

Bruce C Po

Aram M Lindahl

Richard Michael Powell

Baptiste Pierre Paquier

Phillip A Kamp

Guy C Nicholson

Juha O Merimaa

Shaohai Chen

Vladan Bajic

Adam E Kriegel

A system and method is described for determining whether a loudspeaker device has relocated, tilted, rotated, or changed environment such that one or more parameters for driving the loudspeaker may be modified and/or a complete reconfiguration of the loudspeaker system may be performed. In one embodiment, the system may include a set of sensors. The sensors provide readings that are analyzed to determine 1) whether the loudspeaker has moved since a previous analysis and/or 2) a distance of movement and/or a degree change in orientation of the loudspeaker since the previous analysis. Upon determining the level of movement is below a threshold value, the system adjusts previous parameters used to drive one or more of the loudspeakers. By adjusting previous parameters instead of performing a complete recalibration, the system provides a more efficient technique for ensuring that the loudspeakers continue to produce accurate sound for the listener.

Method to determine loudspeaker change of placement

Ambience extraction from a multichannel input signal is provided. The multichannel input signal is converted into a time-frequency representation. A cross-correlation coefficient is computed for each time and frequency in the time-frequency representation of the multichannel input signal. An autocorrelation is computed for each time and frequency in the time-frequency representation of the multichannel input signal. Using the cross-correlation coefficient and the autocorrelation, ambience extraction coefficients including crosstalk and same-side coefficients are computed as a function of a tuning parameter, the crosstalk coefficients being proportional to the tuning parameter and the tuning parameter being between a value of 0 and a value of 1. The ambience extraction coefficients are applied to extract a left ambience component and a right ambience component.

Ambience extraction from stereo signals based on least-squares approach

An anti-noise signal is produced in accordance with an active noise cancellation process (ANC), at an input of a speaker so as to control how much background noise a user can hear. Strength of the anti-noise signal is adjusted gradually, rather than abruptly, in proportion to decreasing or increasing sound pressure level (SPL) of the background noise, during inactivation or activation of the ANC process. Other embodiments are also described and claimed.

ANC system with SPL-controlled output

A system for managing the changing state of an adaptive filter in an active noise control (ANC) system is described. An adaptive filter state storage stores copies of prior states of the adaptive filter. A disturbance detector can detect either normal ambient noise or abnormal ambient noise. An adaptive filter state manager signals that a copy of a current state of the adaptive filter is to be repeatedly written to the state storage, so long as normal ambient noise is being detected. But when abnormal noise is detected, the state manager signals that the adaptive filter be restored to one of its prior states, from the copies stored in the state storage. Other embodiments are also described and claimed.

Robust process for managing filter coefficients in adaptive noise canceling systems

A communications device is configured to control the intelligibility of speech in a downlink voice signal during a call. The device determines a current noise level based on sampling ambient acoustic noise and based on a previously determined noise level. The device then determines an overall output gain and a frequency response based on the current noise level and based on a user-selected volume setting of the device. The device modifies the downlink voice signal during the call in accordance with the determined overall output gain and the determined frequency response. Other embodiments are also described and claimed.

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Los Altos, CA, United States of America

Bruce C Po