Patent ID: 11862140
Assignee: AMS AG
Field: Other consumer goods (Other fields)
Classification: CPC G  H | IPC G  H

Claim 16:
17. An audio system for an ear mountable playback device comprising a speaker, a feedforward microphone that predominantly senses ambient sound and an error microphone that senses sound being output from the speaker, the audio system being configured to perform noise cancellation and comprising a sound control processor that is configured to
record a noise signal from the feedforward microphone and using the noise signal as a detection signal;
filter the detection signal with a feedforward filter;
control a playback of the filtered detection signal via the speaker;
record an error signal from the error microphone; and
determine whether the playback device is in a first state, where the playback device is worn by a user, or in a second state, where the playback device is not worn by a user, based on processing of the error signal
adjust a filter response of the feedforward filter based on the error signal; and
determine the second state based on an evaluation of the filter response of the feedforward filter at least one predetermined frequency; and
determine the second state by determining a linear regression of the filter response of the feedforward filter in a predefined frequency range, the linear regression being defined by at least a filter gradient and a filter gain, and by evaluating the filter gradient and/or the filter gain.