Ultrasonic echo canceler-based technique to detect participant presence at a video conference endpoint

An apparatus comprising:

• a loudspeaker configured to transmit an ultrasonic signal into a spatial region;
• a microphone configured to transduce ultrasonic sound, including an echo of the transmitted ultrasonic signal, received from the spatial region into a received ultrasonic signal;
• a processor coupled to the loudspeaker and the microphone and configured to:
• transform the ultrasonic signal and the received ultrasonic signal into respective time-frequency domains;
• compute an error signal, representative of an estimate of an echo-free received ultrasonic signal, based on the transformed ultrasound signal and the transformed received ultrasonic signals;
• compute power estimates of the error signal over time;
• and
• detect a change in people presence in the spatial region over time based on a change in the power estimates of the error signal over time.

A non-transitory processor readable medium storing instructions that, when executed by a processor, cause the processor to:

• cause a loudspeaker to transmit an ultrasonic signal into a spatial region;
• access a received ultrasonic signal representative of transduced ultrasonic sound, including an echo of the transmitted ultrasonic signal, received from the spatial region at a microphone;
• transform the ultrasonic signal and the received ultrasonic signal into respective time-frequency domains that cover respective ultrasound frequency ranges;
• compute an error signal, representative of an estimate of an echo-free received ultrasonic signal, based on the transformed ultrasonic signal and the transformed received ultrasonic signal;
• compute power estimates of the error signal over time;
• and
• detect a change in people presence in the spatial region over time based on a change in the power estimates of the error signal over time.