Background noise estimation using gap confidence

A system, including:

• a microphone, configured to generate a microphone output signal during emission of sound in a playback environment, wherein the sound is indicative of audio content of a playback signal, and the microphone output signal is indicative of background noise in the playback environment and the audio content;
• and
• a noise estimation system, coupled to receive the microphone output signal and the playback signal, and configured:
• to generate gap confidence values in response to the microphone output signal and the playback signal, where each of the gap confidence values is for a different time, t, and is indicative of a confidence that there is a gap, at the time t, in the playback signal, wherein gap denotes a time or time interval of the playback signal at or in which playback content is missing or has a level less than a predetermined threshold, wherein the gap confidence values include a gap confidence value for each time, t, and the noise estimation system is configured to generate the gap confidence value for each time, t, including by:
• processing the playback signal to determine a minimum in playback signal level for the time, t;
• processing the microphone output signal to determine a smoothed level of the microphone output signal for the time, t;
• and
• determining the gap confidence value for the time, t, to be indicative of how different the minimum in playback signal level for the time, t, is from the smoothed level of the microphone output signal for the time, t;
• and
• to generate an estimate of the background noise in the playback environment using the gap confidence values.