Circumaural headset or headphones with adjustable biometric sensor

A headset includes a circumaural assembly having an adjustable sensor mount configured to secure a sensor forward of the tragus of a user. The mount is movable relative to the assembly to position the sensor in contact with or proximal to the user skin. The mount may extend from an interior side or flat component of the assembly into an opening of a circumaural cushion. The sensor mount may include a resilient support arm or structure extending from behind a circumaural cushion, or integrated into the cushion, to urge the sensor into contact with the user. The mount may include a spring-biased rotatable knob having an eccentrically located aperture configured to secure the sensor, and rotatable to position the sensor. Sensor signals may be processed to detect blood flow, heart rate, etc. and/or movement, such as jaw movement indicative of talking for use in automatically muting an associated microphone.