Study of Improvement of Intelligibility for Elderly Speech Based on Formant Frequency Shift

This study aims at improving speech intelligibility based on the acoustic features of Japanese elderly people. In general, it is difficult for elderly people to tune aging articulators accurately. In the previous research, it was found that the spectral transition distance of elderly speech with non-briskness decreased. In addition, it was found that there was relationship between the formant and spectral transition distance. In this paper, we investigated about difference of spectral transition distance and position of articulation in terms of the level of briskness. In addition, we improved the speech of the elderly people by the signal processing. The method of signal processing is method for shift first formant frequency (F1) and second formant frequency (F2). As the results of analyzing speech with non-briskness and briskness, we found that there was a relationship between the difference of spectral transition distance and position of articulation. It is difficult for elderly speakers to utter /a/ and /i/ to move a large mouth and tongue. And we improved intelligibility of speech with non-briskness by the F1 and F2 shift method in the some words which need large movements of mouth and tongue. In future works, we will investigate analysis and how to improve acoustic features of consonants in the elderly speech.