Development and evaluation of bone-conducted ultrasonic hearing-aid regarding transmission of speaker emotion: Comparison of DSB-TC and DSB-SC amplitude modulation method

Author(s): Takayuki Kagomiya and Seiji Nakagawa

Abstract

Human listeners can perceive speech signals in a voice-modulated ultrasonic carrier from a bone-conduction stimulator even for sensorineural hearing loss patients. Considering this fact, we have developed a bone-conducted ultrasonic hearing aid (BCUHA). However, there remains considerable scope for improvement, particularly in terms of sound quality. Voice-modulated BCU is accompanied by a strong high-pitched tone and some distortion depending on the amplitude modulation method. In this study, the sound quality of a BCUHA with double-sideband transmitted carrier (DSB-TC) modulation and double-sideband suppressed carrier (DSB-SC) modulation methods was examined. The assessment was conducted by examining the transmission of the emotional state of speakers. The evaluation used emotion-identification experiments. Types of emotion included Ekman's basic six emotions ("anger," "disgust,'' "fear," "joy,'' "sadness,'' and "surprise'') and "neutral.'' In addition, a series of subjective evaluations regarding "voice clarity,'' "comfortableness,'' and "preference'' was conducted. The results showed that although DSB-SC sound was superior in "comfortableness'' and "preference,'' voice emotion transmission was more effective in DSB-TC conditions.

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