Naval Device Applications of Relaxor Piezoelectric Single Crystals: Design of a Transducer for Underwater Communications

This proposal is concerned with the use of single crystal PMN-PT as a transducer element in underwater communication systems. The high sensitivity and strain capability of these materials makes them unusually appropriate for the demands of small size and high output needed in this application. Developments already underway as an element in active noise reduction earplugs for personnel on the flight decks of aircraft carriers lead naturally to the use of similar transducers for in-the-ear loudspeakers for personnel carrying out underwater missions, particularly in the littoral ocean zones. Such activities are of particular value in communicating with personnel who will wear ear canal insert earphones resistant to water and pressure, and still maintain a high degree of fidelity, frequency and dynamic range for the presentation of transmitted messages. The same or similar elements can also serve as microphones or hydrophones as part of a two-way communications link. The progress and experience we already have in working with PMN-PT has convinced us of the special advantages that this material has when incorporated into small, high output acoustical drivers, and offers an unusual opportunity to design and prototype a transducer for underwater communications.