Sound output of electronic laryngeal prostheses at room and body temperature

An electronic laryngeal prosthesis, fully-implantable in the neck, is a desirable source of artificial voice. Emitted sound energy in a frequency range suitable for adult males and females must be of the correct period and intensity and rich in powerful harmonics. Any such device places severe demands on a bioencapsulant used to enclose the transducer. Location of the devices within the central neck demands a prosthesis-coating combination capable of passing sound energy at central body temperature. This study reports on four identical prostheses, coated with a polyvinylidene chloride, a copolyether polyurethane, a semi-rigid epoxy, or uncoated. Units were tested at room (72 degrees F) and body (100 degrees F) temperature in a sound-isolated chamber. Results indicated that performance of the uncoated unit was altered due to temperature effects. The presence of the polymer encapsulants did not have any differential effect on sound spectrum due to temperature differences.