Abstract: A system including an acoustic barrier suitable for wearing in or on an ear of an individual mammalian subject, and a processor. The acoustic barrier defines at least one sound path therethrough and includes a microphone for measuring sound pressure inside the acoustic barrier. The processor is arranged to receive measurements from the microphone and determine a risk that a sound dose limit will be reached before a predetermined time associated with the dose limit. The system is arranged to provide an indication of the determined risk.

Abstract: A system for monitoring sound comprising a primary circuit portion and a secondary circuit portion. The primary circuit portion is adapted to alternate between a first state of operation and a second state of operation. In the first state, the primary circuit portion is adapted to monitor sound. The primary circuit portion is adapted to periodically enter the first state with a predetermined frequency. The secondary circuit portion is adapted to monitor sound while the primary circuit portion is in the second state and provide an indication of the sound monitored to the primary circuit portion. The system is adapted to dynamically adjust the frequency with which the primary circuit portion enters the first state based on the indication.

Abstract: A device (1) for insertion into an ear canal of a mammalian subject. The device includes a body (2) having a sound path extending therethough and a tensioned membrane (10) in the sound path. The tensioned membrane has at least one corrugation (12). The device further includes an adjustable member (6) arranged to bear against the membrane to adjust the tension of the membrane and thereby to alter an acoustic response of the sound path. The adjustable member may include a compressible portion (8).