Patent ID: 11882414
Assignee: NXP B.V.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 12:
13. An audio playback system comprising:
a reference signal generator having a reference signal output configured to be coupled to a loudspeaker;
an audio analyser having an audio analyser input configured to be coupled to an acoustic sensor and an audio analyser output; wherein
the reference signal generator is configured to output a reference signal comprising a plurality of sinusoidal waveforms in ultrasound frequency range for output via the loudspeaker; and
the audio analyser is configured to:
receive an audio input signal;
determining a signal-to-noise ratio value based on the received audio signal;
determine a presence level of the reference signal in the received audio input signal based on the signal-to-noise ratio value;
adjust a gain of a subsequently generated reference signal based on the signal-to-noise ratio value; and
output a fault indication dependent on the presence level.