Melhoria da qualidade da voz de deficientes auditivos utilizando-se correção da frequência fundamental.

Abstract

Efforts have been carried out in order to improve the deaf´s communication by means of speech, during the oralization process. In most cases, the deaf can learn how to speak and understand what is said by the listeners. In general, tools with this purpose use visual feedback in the process of speech learning. Nevertheless, there is strong evidence that the tactile stimulus can enhance such process. The parameterization of the fundamental frequency variations of the voice signal, transformed into tactile vibrations, by the use of tactile devices, enables the efficient correction of the fundamental frequency, constituting, thus, an interesting alternative which is applied while aiding the deaf individuals´ oralization. This alternative is equally feasible to individuals with multiple deficiencies, such as the deaf-blind case. With the control of the fundamental frequency of the deaf people, helping them to produce frequencies approximate to the listeners values, a meaningful improvement of voice quality is expected. This research proposes a real time system of correction/learning of the fundamental frequency, evaluating some forms of voice codification by means of tactile stimulus with the objective of contributing to the deaf people’s speech enhancement in the oralization process. Studies on psychophysical sensitivity of people with sensorial, hearing and visual deficiencies are presented as well as in relation to people with none of these deficiencies, with the aim to assess the use of vibrotactile stimulators as sensorial alternative. In these studies, the influences are related to sex, age, and education level, besides the deficiency origin were evaluated. The research still appraises several parameters involved in the voice capture and processing, in the fundamental frequency estimation and in the transformed ones once applied to the conversion of voice information into tactile stimulus. The process of fundamental frequency correction uses a set of objective measures, based on its rightness rate with the intention that once the correction is attained, speech betterment is also achieved. A subjective evaluation concerning the deaf´s speech quality was accomplished before and after the correction process of the fundamental frequency in order to verify the possible speech improvement.