Effects of Phonemic Length Contrast on Perception of Lengthened Sounds:
A Cross-Linguistic Study
Minji KANG (Yonsei University) and Inkie CHUNG (Sogang University)
1. Introduction. Kawai et al. (2007) and Park et al. (2018) claim that English and Korean
listeners perceive a continuum of lengthened fricative /ʃ/ and /s/, respectively, in a gradualmanner. Although speech sounds are generally thought to be perceived in a categorical manner(Eimas et al. 1971; Liberman et al. 1957), it is not yet clear why such gradual mode ofperception is observed with lengthened sounds, and whether the same results will hold for otherlanguages. The current study examines Japanese listeners’ judgments on the abnormality ofdigitally lengthened /s/ sounds. The perceptual results are compared to those of Kawai et al.
(2007) and of Park et al. (2018) to show the effect of phonemic length contrast on listeners’
perception of lengthened sounds.
2. Methodology. Sentence Stimuli and Length Manipulation. A single stimulus sound,
Japanese fricative /s/, in two different phonological contexts were prepared: /s/ in the wordinitial position (/saNka/ ‘participation’) and word-medial position (/hasaN/ ‘bankruptcy’). The
latter context (potentially) exhibits phonemic length contrast between singleton vs. geminate
consonants (/hasaN/ vs. /hassaN/). Meanwhile, the word-initial /s/ cannot exhibit such contrast,
as Japanese geminates do not appear word-initially. Two sentence stimuli in which /saNka/ and/hasaN/ were embedded were recorded by a native speaker of Japanese. Following the methodof Park et al. (2018), each stimulus was lengthened by 20 ms increment for 20 times, creating
total 21 stimuli with a varying frication duration of /s/. Participants and Experiment
Procedure. Six native speakers of Japanese (six females, mean age = 25.1, SD = 4.2) listened
to a series of sound files (where Japanese fricative /s/ varied along with its frication duration)and rated with 1-100 rating scales [1: normal, 100: abnormal] how normal (or abnormal) thefricative /s/ sounded. The participants rated each of the 21 stimuli for 5 different times in arandom order. The curvilinear regression analysis was made for the perceptual results.
3. Results and Conclusion. On the curvilinear regression graph, the word-initial /s/ exhibits asigmoidal curve, similar to the results of English /ʃ/ in Kawai et al. (2007) and of Korean /s/ inPark et al. (2018). On the other hand, the word-medial /s/ shows a sharply increasing slope near
70 ms. Such discrepancy may be due to the following difference between the two phonologicalcontexts: (1) English and Korean fricatives in general and Japanese word-initial /s/ do notexhibit phonemic length contrast, and such absence would make the durational information ofa speech sound marginal (or phonologically irrelevant). On the other hand, (2) in the case ofJapanese word-medial /s/, the duration becomes the primary cue in determining the phoneme
status of segmental duration and thus a word’s meaning. Hence, we argue that the linguisticrelevance (or meaningfulness) of a speech sound’s segmental duration (which is determined by
the phonological context which exhibits or does not exhibit phonemic length contrast) plays acrucial role in determining listeners’ sensitivity in their judgments on the abnormality oflengthened sounds.
References. Eimas et al. 1971. Speech perception in infants, Science, 171. Kawai et al.
2007. Listeners’ identification and discrimination of digitally manipulated sounds asprolongations. J. Acoust. Soc. Am. 122. Liberman et al. 1957. The discrimination of speechsounds within and across phoneme boundaries. J. Exp. Psychol. 54. Park, et al. 2018.
Comparison of perception of the prolonged /s/ in Korean by average adult listeners andspeech-language pathologists. Audiol. Speech Res. 14.