Nokia Corporation

Wolfson Microelectronics Limited

Khaldoon Taha Al-Naimi

Ahmet Kondoz

Abid Rashid

Stephane Villette

A method of controlling a noise cancellation system, for use in an audio device, comprises: generating an ambient noise signal representative of ambient noise; filtering and applying gain to the ambient noise signal to generate a noise cancellation signal; passing the noise cancellation signal to a speaker; and generating an error signal from an error microphone, wherein the gain applied to the ambient noise signal is controlled based on the error signal, and the method further comprises: determining from the error signal whether the audio device is in an off-ear position, and controlling the noise cancellation system based on said determination as to whether the audio device is in the off-ear position.

Noise cancellation system

To alleviate problems of signal aliasing and to reduce complexity, Linear Predictive Coefficients (LPCS) are calculated from samples of audio signals and Line Spectral Frequency (LSF) vectors are extracted from the LPCs with a rate higher than a desired vector rate, the LSF vectors comprising values of different LSF parameters. Next, an LSF track is formed for at least one of the LSF parameters. At least one of the formed LSF tracks is then low pass filtered. Finally, decimated LSF vectors are reconstructed from the low pass filtered LSF tracks, the decimated number corresponding to the desired vector rate. The invention equally relates to a corresponding computer program, to corresponding devices and to a corresponding communication network.

Growing community of inventors

Guildford, United Kingdom

Khaldoon Taha Al-Naimi