Artificial larynges: a review and development of a prototype self-contained intra-oral artificial larynx.

New means of speaking after laryngectomy or loss of continuity of the airway have consisted of: 1. Pharyngostome with artificial larynx (artificial mechanism connecting the trachea to the pharynx). 2. Artificial sound to nose or mouth (e.g., bellows, grammaphone). 3. A reed device from tracheostome to the mouth or the nose. 4. Tracheoesophageal fistula with or without a communicating connecting device. 5. Transcervical sound source which is used by placing a sound source on the external neck transmitting the sound into the pharynx. 6. The implanted sound source, or 7. Intra-oral sound source. This paper will review devices used to aid in artificial speech production provided in the past. No attempt will be made at reviewing the surgical literature on voice conservation procedures. Four sections are presented: 1. Early History of Laryngectomy and Review of Historical Artificial Larynges, 2. History of Alaryngeal Speech Production Without an Artificial Device, 3. Studies of Speech Production, Comparisons of Esophageal and Artificial Laryngeal Speech, and 4. Development of the Prototype Self-Contained Intra-Oral Artificial Larynx; synopsis of references reviewed in the first three sections; and a presentation of our new device in the fourth section. Each review is presented in chronological order with dates provided. Each of the first three sections is independent but relates to the common problem of alaryngeal speech. At the onset of design the self-contained intra-oral artificial larynx was thought to be only for persons after laryngectomy who for some reason could not attain esophageal speech. Later it became apparent that there are others, such as quadriplegics with tra-cheostomies, who could also benefit from an artificial larynx which is orally controlled. The artificial larynx being tested at present in our lab is fitted into a dental plate or dental shim with a hearing aid speaker and a built-in exponential horn which opens posteriorly. This artificial larynx is in its third revision and, at present, is externally wired during the testing phases. In its final form the power supply, electronic circuits, off-on switch, speaker and exponential horn will be completely contained in the dental prosthesis. Modifications are being made to obtain appropriate loudness with a decreased voltage requiring fewer batteries fitted into the prosthesis. The circuits will be placed on a microcomputer chip after the best circuits have been obtained by testing externally placed hard wired circuits on several objects. [ABSTRACT FROM AUTHOR]