Design of Transducers for Underwater Communications and Hearing Protection

This proposal is concerned with two important aspects of sound as it affects divers; the ability to receive and send communications (“comms”), and the effects of ambient noise, particularly in construction and demolition activity. SCUBA divers wear a breathing apparatus and their ears are often flooded so that systems that occlude the ear canal that are satisfactory at sea level pose a danger as the ambient pressure changes. Helmeted divers have “dry” ear canals but the issue of changing pressurization remains. Pilots and flight deck personnel are being supplied with active noise reduction (ANR) systems that provide both noise reduction and comms that use both muffs and in-the-ear-canal speakers. This proposed effort is focusing on how the two needs for hearing protection and communications can be achieved for both SCUBA and helmeted divers. The work relies heavily on our Phase I effort on underwater communications and concurrent work on an ANR system for Air Force and Navy flight deck personnel, both of which make use of single crystal relaxor ferroelectric (lead magnesium niobate - lead titanate) materials to generate sound. Different types of transducers, their layout, and the electronic design are being considered to achieve both ANR and communications goals.