Human speech development for an implantable artificial larynx.

An electromagnetic artificial larynx was implanted in two volunteer laryngectomees. Both patients were able to communicate well, but the voice quality still needed improving. Therefore, in this investigation, listener judgments were obtained of 22 different sound sources with a view to incorporating the preferred speech sound in a new version of the device. Electroglottograms were used as sound sources in a speech synthesizer and sentences were produced with different voice qualities for judgmental tests. The results of the listening tests showed a distinct preference for waveforms corresponding to a long completely open phase, a very brief completely closed phase, and an abrupt closing gesture. The optimum acoustic characteristics for the device will be used by electrical engineers to manufacture a new version of the artificial larynx with an improved voice quality.