The perception of morae in long vowels comparison among Japanese, Korean and English speakers

There are three kinds of Tokushuhaku (the specific timing morae) in the Japanese language such as the moraic nasal, the non-nasal consonant and the long vowel. Even though Japanese native speakers can perceive them perfectly, it is difficult for Japanese learners from abroad to perceive and produce them. To make it more efficient for Japanese learners to acquire them, we need to investigate how Japanese native speakers perceive Tokushuhaku. This study examines the perception of a mora or morae of Japanese language specifically in the long vowel. Previous researchers (Hiroya Fujisaki, Miyoko Sugito) have assumed that duration contrasts alone are involved in perception. However we hypothesize that the accentual change in the midst of a long vowel would mark the boundary between the morae and would affect the perception of morae by native speakers of standard Japanese. Based on the hypothesis three kinds of perception tests with computer-edited sound stimuli were given to native Japanese, Korean and English speakers. The results of these tests suggest that native Japanese speakers count the number of morae not only by the duration of vowels, but also by the accentual change which indicates the boundary between morae. On the other hand, nonnative speakers count the number of morae only by the duration of vowels. 1. JAPANESE SYLLABLE, MORA AND ACCENT The phonetic units of English and Korean are syllables, and the units of Japanese are syllables and morae. 'Japanese', 'English' and 'Korean' are divided into syllables as 'ja•pa•nese', 'eng•lish' and 'ko •re•an'. The same meaning words in Korean are divided into syllables as 'il•bo•neo', 'yeo•ngeo', 'han•gu•geo' and the words in Japanese 'ni•hon•go', 'e :•go' and 'kan•ko•ku•go'. The Japanese words are also divided into morae as 'ni•ho•n•go', 'e•e•go' and 'ka• n•ko•ku•go'. Japanese native speakers divide the word 'nihongo' (Japanese) into syllables as 'ni•hon•go' and also into morae as 'ni• ho•n•go'. In the former, each syllable is the sound cluster to pronounce with ease and in the latter, each mora is the unit of time. Japanese natives perceive that each mora has the same length. The difference between 'ho•ne' (bone) vs. 'ho•n•ne' (true feeling) is the existence of the nasal Tokushuhaku 'n', and the difference between 'ki•te' (wear and) vs. 'ki•t•te' (stamp) is the existence of the non-nasal consonant Tokushuhaku 't', and 'ku•tu' (shoe) vs. 'ku•tu• u' (pain) the existence of vocalic Tokushuhaku 'u'. The sentences have intonations and the words have accents in the spoken languages. The functions of accent is to divide the chain of sounds into some parts that compose the sentence, and to distinguish the meanings of the words composed with the same speech sounds. English has stress accent, Japanese has pitch accent and Korean has neither stress nor pitch accent. Korean has no accent to distinguish the meanings and has liaison to clarify the relations between the parts in sentences. The Japanese sound, '_ga ̄ k•ko•o_kyo ̄ o•i•ku' (the pitch of the morae 'ga' and 'kyo' which follow ''_'', is low, and the pitch of the morae 'k•ko•o' and 'o•i•ku' which follow '' ̄ '', is high) means 'school, education' and '_ga ̄ k•ko•o•kyo_o•i•ku' means 'school education'. We have a Japanese minimal pair: '_ha ̄ si' (bridge) vs. '̄ ha_si' (chopsticks). Only the difference of the accent distinguishes these two words. In the accent system of the standard Japanese the pitch of the first mora is always different from the pitch of the second as '_ha ̄ si', ' ̄ ha_si', '_a ̄ me' (candy) vs. ' ̄ a_me' (rain). 2. THE EXPERIMENT USING A SEQUENCE OF VOWELS INTERRUPTED BY A CONSONANT 2.1. Procedure The nonsense words [_a ̄ tade_s], [_a ̄ taade_s] pronounced by an adult male standard Japanese speaker were used for the experiment as the sound stimuli. The original sounds were recorded into a digital audio tape and the sound stimuli were created by 2) PICOLA (Pointer Interval Control OverLap and Add). The duration of the first vowel [a] of [atades] was shortened in 3 stages (1.0, 0.6, 0.3), and at the same time the duration of the second vowel [a] was lengthened in 5 stages (1.0-2.0). The duration of the first vowel of [ataades] was lengthened in 3 stages (1.0, 1.2, 1.5), and at the same time the duration of [aa] after the consonant [t] was shortened in 6 stages(1.0-0.375). The total number of the sound stimuli was 33, and 10 sets of these stimuli were recorded into a digital audio tape at random. The subjects were divided into the three groups; 10 native Japanese speakers (group J1), 9 native Korean speakers (group K1), 9 native English speakers (group E1). The subjects were asked to listen to the tape using headphones and to mark the one of 4 choices closest to what they perceived; “atadesu”, “aatadesu”, “ataadesu”, and “aataadesu” written in Japanese Hiragana for J1, Korean Hankul alphabet for K1 and romanization for E1 on the answer sheets.