Abstract:Articulatory and acoustic studies have provided evidence that in word-initial and word-final positions, English /l/ exhibits substantial differences in 'darkness': dark [ɫ] in word-final position is produced with a more retracted tongue dorsum and lowered tongue body than light [l] in word-initial position. The darkness of intervocalic /l/, however, is variable. While Sproat and Fujimura (1993) argue that /l/ darkness is on a continuum strongly affected by duration, Hayes (2000) maintains that the morphological status of intervocalic /l/s should affect whether they are produced as light or dark variants. In this study, ultrasound imaging is used to investigate whether the morphological affiliation of the /l/ affects the degree of tongue dorsum retraction and tongue body lowering and the acoustic characteristics of /l/ darkness. Six American English speakers produced three types of stimuli which were predicted to increase in darkness in the following order: (1) when /l/ corresponded with the onset of a suffix (e.g., flaw-less), (2) when /l/ corresponded with the final position of the stem word (e.g., tall-est), and (3) when /l/ was the final consonant of a stem word (e.g., tall). For both articulatory and acoustic measures, the predicted order was upheld. The strongest articulatory correlate of darkness was tongue body lowering, and acoustic differences were mainly manifested in F1 and normalized intensity. Phonological implications of these findings are discussed.

The present study investigates the articulatory and acoustic properties of the unique apical segments in Mandarin Chinese that occur after dental and retroflex sibilants instead of the high front vowel [i]. An ultrasound study showed that the segments are homorganic with the preceding dental and retroflex sibilants. However, an acoustic study showed that they have a periodic waveform and clear formant structures with no inherent frication noise, indicating that they are not ‘voiced fricatives’. The results also suggest that the observed F2 pattern can only be explained with an acoustic model of a sonorant consonant, wherein F2 is attributed to the cavity behind the apical constriction. Based on this, it is argued that the segments can be best seen as ‘dental approximant []’ and ‘retroflex approximant [ɻ]’. A phonological implication of the pattern is also discussed: the co-occurrence restriction with the high front vowel eliminates a potential chance of palatalization of the dental and retroflex sibilants that may lead to neutralization of the place contrast. The tongue front gesture in the following approximants seems to provide an additional cue to the place of the preceding consonants; the low F3 of [ɻ], for example, enhances cues to the place of the preceding retroflex sibilant.

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This study presents empirical evidence from read vs. interactive speech to shed light on the nature of the alveolar-retroflex sibilant merger by young speakers of Taiwan Mandarin (TM). TM speakers often merge the two sibilants through deretroflexion of the retroflex category. The results of the read speech showed that the variation is on a full continuum, from a complete merger to clear contrasts, and the merger is more prevalent among male speakers, demonstrating the impact of the social stigma associated with the merger. However, the results of the interactive task demonstrated that speakers who merged the contrast produced the retroflex sounds as distinct from their alveolar counterparts, revealing hidden structures in the mental lexicon. The mismatch between the abstract phonological knowledge and actual implementation in production suggests that the exposure to phonological systems of other speakers, especially those who make clear distinctions, has led to the incorporation of discrete categories into the phonological knowledge of the merged speakers. These findings suggest that large individual variation in the early stages of sound change may provide evidence for possible categories in a given language for language learners; however, their implementation may be further modulated by social as well as other phonetic factors.

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