VOICE PROSTHESES WITH A SOUND-PRODUCING M ETALLIC REED ELEMENT - EXPERIMENTAL AND INITIAL CLINICAL-RESULTS

Following total laryngectomy the voice is produced by esophageal speec h as well as with voice prostheses by vibrations of pharyngeal mucosal folds. This pharyngeal sound normally has a significantly lower funda mental frequency than the healthy voice (men about 120 Hz, women about 240 Hz, pharyngeal voice about 70 Hz), which is a handicap especially for female laryngectomy patients. In order to improve the postlarynge ctomy voice, a new type of voice prostheses containing an integrated s ound-producing metallic reed element was developed (ADEVA(R) Company, Lubeck, Germany). Methods/Patients: Thirty-five of these new sound-pro ducing voice prostheses were tested in vitro for different prosthesis- specific physical parameters (pressure, flow, sound pressure, flow res istance, frequency range). In 15 voice prosthesis speakers, a sound-pr oducing prosthesis was introduced during a routine outpatient visit. B esides measurement of the above mentioned physical parameters in patie nts with conventional and sound-producing prostheses, the resulting vo ice was also evaluated by means of a video recording. Results: In vitr o all prostheses with the metallic reed element produced a clear sound . Flow resistance of the prostheses was slightly elevated by the reed element. Insertion of the prostheses was hindered by the reed element. Period of uninterrupted sound production was prolonged after insertio n of a sound-producing prosthesis and patients could speak on a lower pressure level, but the sound of the reed element was permanently dist inguishable only in 6 of 15 patients. Conclusions: In principle a vari ation of the pharyngeal voice by means of a sound producing element, w hich is integrated into a voice prosthesis, is possible. The current d esign of the metallic reed element tested is not yet suitable for rout ine clinical use: 1.The reed element is too sensitive and is easily da maged during insertion, so the insertion device has to be improved. 2. The sound producing element is blocked by small amounts of tracheal s ecretions, so that this element should be replacable separately withou t requiring removal of the silicone valve (if possible by the patient himself). Prior to insertion of the sound producing voice prosthesis t he maximum air flow through the shunt should be measured to determine if the patient can produce the necessary air flow for activation of th e reed element. A further improvement for these special types of voice prostheses would be a sound producing element, which generates a vari able frequency of sound. Limiting the patient to only one fundamental frequency creates a monotone, which does not sound naturally. Initial progress toward a sound-producing voice prostheses has been made. This should be followed by the necessary improvements in order to improve the feasibility of this design for routine clinical use.