Intelligibility of Interrupted Japanese Vowels

Abstract

In order to determine the role of the time factor in speech perception, and to apply this knowledge to the diagnosis of retrocochlear deafness, the intelligibility of periodically interrupted Japanese vowels was investigated. Interrupted speech sounds were produced by interruption synchronized with the fundamental frequency. Sound-time and silent-time fractions were controlled by an electronic switch. The results of two experiments showed that /a/, /e/ and /i/ are vowels of high redundancy, and /u/ and /o/ have low redundancy. No significant portion of the fundamental period needed to identify each vowel was found, but a duty cycle of above 0.5 was necessary for the identification of interrupted vowel sounds. The question of whether monosyllables or words are better test materials in the diagnosis of deafness is discussed with regard to their respective degrees of redundancy.