The intelligibility and its relations to acoustic characteristics of English /s/ and /esh/ produced by native speakers of Japanese

This paper examined the intelligibility of English / / and / / followed by the vowel / / produced by 20 native speakers of Japanese (JE / /, JE / /), and the acoustic characteristics of JE / / and / / according to the different levels of intelligibility. Five native English speakers evaluated the intelligibility of JE /s/ and / / in the word-initial position of “seat” and “sheet.” The major energy peak locations were analyzed for / / and / / produced by Japanese speakers and native English speakers, and for the Japanese sibilant / /. It was found that the overall intelligibility was lower for JE / / than for / / and that JE / / and / / with low intelligibility were heard as / / and / /, respectively. When the intelligibility was lower, JE / / had energy peaks in the lower frequencies, and JE / /, in the higher frequencies, having characteristics similar to / /. L1 transfer occurred in the pronunciation of English / / and / / by Japanese speakers.