Artificial larynx using PZT ceramic vibrator as a sound source (the characteristic improvement of PZT ceramic vibrator)

Various speech production substitutes which aim to reconstruct speech function have been developed and used practically, for vocalizing handicapped persons. However, conventional speech production substitutes have problems. In order to develop perfect speech production substitutes, we paid attention to the PZT ceramic vibrator as a sound source of an artificial larynx. We produced an artificial larynx using a PZT ceramic vibrator, and we evaluated its performance. The power spectrum of produced artificial larynx user´s voice is similar to that of an unhandicapped person´s voice. The vocalized sound of the produced artificial larynx user shows good characteristics at formant frequency with the role which is important for the vowel discrimination. However, the resonant frequency of the vibrator is high, and it is difficult to generate sound near 125 Hz. Thus, we researched a method for lowering the frequency of the generated sound. In this report, we tried to reduce the frequency of the generated sound by using an added mass