Mora Timing Research Articles

An experimental study of Korean rhythm structure on the basis of rhythm metrics

This paper investigates the rhythm structure of Korean. Metrics used in this study included %V, ΔC, Varco V, nPVI-V, and rPVI-C, which have been shown to reflect differences in rhythm structure (stress-, syllable-, and mora-timing) across languages. Ten female native Koreans each produced 20 short declarative Korean sentences. The rhythm metric results of Korean were compared to those of English, Spanish, and Japanese using raw data from previous studies [Ramus et al. 1999, Cognition 73, 265-292; White and Mattys, 2007, Journal of Phonetics 35, 501-522; Grenon and White, 2008, BUCLD 32, 155-166]. Results indicate that Korean combines aspects of both syllable timing and mora timing. Korean has a similar ΔC, Varco V, and nPVI-V to syllable-timed languages. Korean has a similar %V and nPVI-V to mora-timed languages. These data show that instead of belonging to one of three distinct rhythm categories, languages may be placed along a rhythm structure continuum. On such a continuum, Korean is placed between syllable-timed and mora-timed languages, and distinct from stress-timed languages.

Assessment of Mora Timing in Japanese Utterances by Foreign Students Using Phonetic Segments System(<Feature Articles>Rhythm and Timing)

Assessment of Mora Timing in Japanese Utterances by Foreign Students Using Phonetic Segments System(<Feature Articles>Rhythm and Timing)

Influence of L1 on the Acquisition of Japanese Mora Timing by Native Speakers of English and Korean

Influence of L1 on the Acquisition of Japanese Mora Timing by Native Speakers of English and Korean

The comparison between Thai and Japanese temporal control characteristics using segmental duration models

This paper compares the temporal control characteristics between Thai and Japanese read speech data using segmental duration models. The same and the different control characteristics have been observed from phone level to sentence level. The language-dependent and language-independent control factors have also been observed. In phone and neighboring phone level, different characteristics are found. Japanese vowel durations are mainly compensated by only adjacent preceding and following phones, which results from mora timing. Unlike Japanese, Thai vowel durations are affected by two succeding phones. It can be guessed that the differences come from syllabic structures. In word level, most content words tend to have longer phone durations while function words have shorter ones. In phrase level, both languages express duration lengtening of syllable/mora at the phrase initial and final. For language-specific factors, Thai tones express small alteration on phone duration. The comparisions explore the duration characteristics of the languages and give more understanding to be used in speech synthesis and second-language learning research. [Work supported in part by Waseda Univ. RISE research project of ‘‘Analysis and modeling of human mechanism in speech and language processing’’ and Grant-in-Aid for Scientific Research A-2, No. 16200016 of JSPS.]

Effects of speaking style on the regularity of mora timing in Japanese

The regularity of mora timing in Japanese has remained controversial over the years [Warner and Arai, Phonetica 58, 1–25 (2001)]. It is possible that the degree of regularity varies with speaking style. Four Japanese subjects spoke six‐mora proper names with varying syllable structures where the second name had either three simple syllables (e.g., Tomiko) or two syllables with a long vowel (e.g., Tooko) or a long consonant (e.g., Tokko). These were read either in formal sentences, read in conversational style sentences, or used in spontaneous description of pictures of characters having these names. Moras were measured as the intervals between vowel onsets using an automatic vowel‐onset detection algorithm. Although all styles suggested regular mora timing, the results show that the styles differ in the degree of temporal compensation for the moras constituted by long vowels and long consonants which are shorter than consonant‐vowel syllables. The compensation was clearest in the most formal style of speech.

Japanese mora‐timing and processing: The case of devoiced vowels

An extensive literature has argued that Japanese speakers compensate for inherent durational differences to keep moras to approximately equal lengths (e.g., Han, 1962; Port et al., 1980; Minagawa‐Kawai, 1999; reviewed in Warner and Arai, 2001a). However, near‐regularity of moras may not be because of intentional compensation (Warner and Arai, 2001b). This paper examines Japanese listeners processing, rather than production, of one case of irregularly timed moras: vowel devoicing. When Japanese vowels are devoiced, the mora tends to be shorter than usual. If speakers aim for regular timing, one might predict that listeners would also expect moras to be regularly timed and would thus have difficulty processing sequences that deviate from regular mora timing. However, one could predict that listeners are aware of what deviations from regular timing to expect, and thus have no difficulty processing timing deviations. The results, from phoneme monitoring and lexical decision tasks, show that listeners only have difficulty processing devoiced vowels in environments where devoicing would not be expected. In fact, where devoicing would be typical, listeners find devoiced vowels easier to process. This suggests that in processing, knowledge of patterns in the language outweighs any bias toward regularly timed moras.

Representations of within‐word structure and Japanese speech timing

One complication about the debate of mora timing is that durational units are closely related to syllable structure in which morae can be treated as subunits of syllables. As a consequence, durational properties of the components in three types of syllables, CVN, CVV, and CVQ, can equally be examined from the point of representations of within‐word structure. Durational properties in Japanese speech timing undoubtedly play an important role, but knowledge of representations of within‐word structure cannot be neglected because it is uniquely language specific. In this presentation it is discussed how knowledge of representations of within‐word structure plays a significant role in recognition of morae from the point of psycholinguistic framework, presenting various types of data that were collected from (1) Japanese preschool children (before and after acquiring kana orthography), (2) Japanese monolinguals and Japanese English bilinguals, and (3) Japanese L2 learners (from beginning to advanced whose native language is English). Also reported are data from Telugu (a Dravidian language spoken in India), whose speech segmentation mechanism behaves like that of mora‐timed language. It is hoped that knowledge of representations of within‐word structure together with the durational properties will facilitate Japanese learners to acquire Japanese speech timing.

Effects of speaking rate on mora timing organization in producing Japanese contrastive geminate/single consonants and long/short vowels by native and Chinese speakers

Effects of speaking rate on mora timing organization in producing Japanese contrastive geminate/single consonants and long/short vowels by native and Chinese speakers

Phonological representation in Japanese and American rap music: Further evidence for mora timing

This paper investigated how words in Japanese and American rap music were represented in terms of two phonological units, morae and syllables. The main question addressed in this study was to find out which unit was preferred to represent words in Japanese and American rap music. One hundred CVN syllables in two or multi-syllable words were identified from 9 pieces of 2 Japanese musical bands and 27 pieces of 3 American musical bands. Then, the first author set these syllables to music one by one, using a Japanese computer music software to determine how these syllables were assigned to notes. The analysis showed that 73% of the CVN syllables in Japanese rap music were assigned to a note which was two times longer than that of the following note and 27% were assigned to two separate equivalent notes, while 93% of the CVN syllables in American rap music were assigned to a single note which was equivalent to the following note. In other words, the computation of duration was considered to choose notes in the former, while it was not in the latter, suggesting that words in Japanese and American rap music were represented in terms of morae and syllables, respectively.

Acoustic manifestations of mora timing in Japanese

Segment durations in 20 minimal-paired words in Japanese were examined to identify regular patterns of acoustic manifestations of mora timing in Japanese. The results indicate that segments consistently stretch or compress, providing temporal compensation within a mora and between moras, to attain targeted length at the word level. A segment is 11% longer in the pre-geminate-stop position than in the pre-single-stop position; in the word final position, a segment is 9% shorter following a geminate stop than a segment following a single stop; and [t] in the same phonotactic environment shows varied durations according to different moraic conditions. Fricatives followed by a devoiced vowel are considerably longer than any other inherently long, nonmoraic segments, and are comparable to moraic segments and the average mora duration. Syllable durations are not isochronous, varying by as much as 50%. The word duration is affected more by the number of component sounds and their inherent durations in two-mora than in three-or four-mora words. When the word durations are converted into ratios, they are markedly similar to the mora values. The results suggest a timing control mechanism adjusting segments to obtain targeted word durations. These phenomena describe mora timing in Japanese.

Rhythm type and articulatory dynamics in English, French and Japanese

In the study reported here, movement data were analyzed for archetypes of the three most widely recognized temporal organization categories: English for stress timing, Japanese for mora timing, and French for syllable timing. Reiterant speech productions from the three languages were elicited and analyzed as commensurately as possible, using the experimental methodology employed originally by Kelso, Vatikiotis-Bateson, Saltzman & Kay [ Journal of the Acoustical Society of America (1985) 77, 266–280] for two speakers of English. The primary aim was to show the extent to which simple kinematic analysis of a primary articulator (the lower lip–jaw complex) can reveal universal and language-specific aspects of temporal organization and prosody. For the most part, kinematic results were like those of Kelso et al. (1985): most of the spatiotemporal variability of the movement behavior could be accounted for in the highly linear covariation of peak velocity and displacement. Moreover, there were clear condition-specific correlates of stress in English and French, of accent-related tone and mora complexity in Japanese, and speaking rate in all three languages on displacement and on the slope of the linear relation between peak velocity and displacement. These results are interpreted in terms of an abstract, yet simple, second-order system such as a linear spring–mass. By setting a small number of underlying parameters, such a system can characterize the overall spatiotemporal behavior of the lip–jaw system, as well as most of the specific linguistic and performance distinctions in stress, speaking rate and the like.

Effects of the mora and segmental features on word duration in Japanese

Word duration in Japanese is determined by number of moras when words are pronounced at a normal speaking tempo in focus position in carrier sentences [Port et al., J. Acoust. Soc. Am. 81, 1547–1585 (1987)]. Still, variation in segmental makeup has some effect on work duration. It was expected that, when out of focus position or when spoken at faster tempo, durations for words with a given number of moras would show more variation. A set of Japanese words of two, three, and four moras having various syllabic templates (e.g., tokki, tooki, etc.) was chosen. They were produced in both focus position and nonfocus position (by changing a nontarget word from sentence to sentence) at two tempos. Words with same mora length exhibited less word‐to‐word variation at slow tempo than fast, and less variation in the focus position than when nonfocused. To factor out segmental effects, subjects were asked to produce each sentence reiterantly by replacing each mora of the target word with ta. As expected, reiterant results showed almost no variation due to original segments and much less effect of sentence position and tempo. The results suggest that competing constraints affect Japanese timing: a mora constraint (“make all moras equal”) plus intrinsic segmental constraints (different for each segment type). Mora timing dominates at slower tempos and in focus position, but can be overpowered by constraints of intrinsic segmental duration elsewhere. [Work supported by NSF, DCR‐85‐18725.]

A reexamination of the compensation effect in the mora hypothesis

The objective of this paper is to reexamine the compensation effect of the mora hypothesis in mora timing. An early investigation of the mora hypothesis presented the compensation effect in Japanese as evidence in support of the mora hypothesis [Port et al., Phonetica 37, 235–252 (1980)] and another presented contrary evidence against it [M. Beckman, Phonetica 39, 113–135 (1982)]. However, since Port et al.'s evidence was obtained in comparison with different test words produced by Japanese and Arabic speakers, their results need to be reexamined. In this paper, an experiment was conducted as to whether the compensation effect observed in Port et al.apos;s experiment will be relevant only to a mora-timed language by using the identical test words produced by Japanese and Arabic speakers. Contrary to Port et al.'s results, the results of this experiment indicated that the compensation effect was observed not only in Japanese but also in Arabic. These data indicate that the compensation effect may not be evidence for the mora hypothesis.

Evidence for mora timing in Japanese.

Japanese has long been described as a "mora-timed" language by linguists. Japanese pedagogy has traditionally claimed that moras are constant in duration. Four experiments are reported investigating segmental timing in Japanese in order to test several straightforward hypotheses about mora timing. First, it is demonstrated that words with an increasing number of moras increase in duration by nearly constant increments. The next two experiments explored the mechanisms by which constant mora durations are achieved given that there are large universal differences in the inherent duration of various segment types (e.g., /u/vs/a/), and given that some syllables are supposed to be two mora long (such as, those with long vowels or final consonants). In each case, it was found that the duration of a word stays very close to a target duration that depends on the number of moras in it. This is achieved by stretching or compressing the duration of neighboring segments and adjacent moras. Thus increasing the number of segments in two-mora syllables results in lengthening, not the expected shortening, of other segments in the heavier syllable.