Structured speaker variability in Japanese stops: Relationships within versus across cues to stop voicing.

A number of recent studies have observed that phonetic variability is constrained across speakers, where speakers exhibit limited variation in the signalling of phonological contrasts in spite of overall differences between speakers. This previous work focused predominantly on controlled laboratory speech and on contrasts in English and German, leaving unclear how such speaker variability is structured in spontaneous speech and in phonological contrasts that make substantial use of more than one acoustic cue. This study attempts to both address these empirical gaps and expand the empirical scope of research investigating structured variability by examining how speakers vary in the use of positive voice onset time and voicing during closure in marking the stop voicing contrast in Japanese spontaneous speech. Strong covarying relationships within each cue across speakers are observed, while between-cue relationships across speakers are much weaker, suggesting that structured variability is constrained by the language-specific phonetic implementation of linguistic contrasts.

A comparison of acoustic and articulatory parameters for the GOOSE vowel across British Isles Englishes.

This study quantifies vocalic variation that cannot be measured from the acoustic signal alone and develops methods of standardisation and measurement of articulatory parameters for vowels. Articulatory-acoustic variation in the GOOSE vowel was measured across 3 regional accents of the British Isles using a total of 18 speakers from the Republic of Ireland, Scotland, and England, recorded with synchronous ultrasound tongue imaging, lip camera, and audio. Single co-temporal measures were taken of tongue-body height and backness, lip protrusion, F1, and F2. After normalisation, mixed-effects modelling identified statistically significant variations per region; tongue-body position was significantly higher and fronter for Irish and English speakers. Region was also significant for lip-protrusion measures with Scottish speakers showing significantly smaller degrees of protrusion than English speakers. However, the region was only significant for acoustic height and not for frontness. Correlational analyses of all measures showed a significant positive correlation between tongue-body height and acoustic height, a negative correlation between lip-protrusion and acoustic frontness, but no correlation between tongue-body frontness and acoustic frontness. Effectively, two distinct regional production strategies were found to result in similar normalised acoustic frontness measures for GOOSE. Scottish tongue-body positions were backer and lips less protruded, while English and Irish speakers had fronter tongue-body positions, but more protruded lips.

The role of gesture delay in coda /r/ weakening: An articulatory, auditory and acoustic study.

The cross-linguistic tendency of coda consonants to weaken, vocalize, or be deleted is shown to have a phonetic basis, resulting from gesture reduction, or variation in gesture timing. This study investigates the effects of the timing of the anterior tongue gesture for coda /r/ on acoustics and perceived strength of rhoticity, making use of two sociolects of Central Scotland (working- and middle-class) where coda /r/ is weakening and strengthening, respectively. Previous articulatory analysis revealed a strong tendency for these sociolects to use different coda /r/ tongue configurations-working- and middle-class speakers tend to use tip/front raised and bunched variants, respectively; however, this finding does not explain working-class /r/ weakening. A correlational analysis in the current study showed a robust relationship between anterior lingual gesture timing, F3, and percept of rhoticity. A linear mixed effects regression analysis showed that both speaker social class and linguistic factors (word structure and the checked/unchecked status of the prerhotic vowel) had significant effects on tongue gesture timing and formant values. This study provides further evidence that gesture delay can be a phonetic mechanism for coda rhotic weakening and apparent loss, but social class emerges as the dominant factor driving lingual gesture timing variation.

On the Tail of the Scottish Vowel Length Rule in Glasgow.

One of the most famous sound features of Scottish English is the short/long timing alternation of /i u ai/ vowels, which depends on the morpho-phonemic environment, and is known as the Scottish Vowel Length Rule (SVLR). These alternations make the status of vowel quantity in Scottish English (quasi-)phonemic but are also susceptible to change, particularly in situations of intense sustained dialect contact with Anglo-English. Does the SVLR change in Glasgow where dialect contact at the community level is comparably low? The present study sets out to tackle this question, and tests two hypotheses involving (1) external influences due to dialect-contact and (2) internal, prosodically induced factors of sound change. Durational analyses of /i u a/ were conducted on a corpus of spontaneous Glaswegian speech from the 1970s and 2000s; four speaker groups were compared, two of middle-aged men, and two of adolescent boys. Our hypothesis that the development of the SVLR over time may be internally constrained and interact with prosody was largely confirmed. We observed weakening effects in its implementation which were localised in phrase-medial unaccented positions in all speaker groups, and in phrase-final positions in the speakers born after the Second World War. But unlike some other varieties of Scottish or Northern English which show weakening of the Rule under a prolonged contact with Anglo-English, dialect contact seems to be having less impact on the durational patterns in Glaswegian vernacular, probably because of the overall reduced potential for a regular, everyday contact in the West of Scotland.

Toward "English" Phonetics: Variability in the Pre-consonantal Voicing Effect Across English Dialects and Speakers.

Recent advances in access to spoken-language corpora and development of speech processing tools have made possible the performance of "large-scale" phonetic and sociolinguistic research. This study illustrates the usefulness of such a large-scale approach-using data from multiple corpora across a range of English dialects, collected, and analyzed with the SPADE project-to examine how the pre-consonantal Voicing Effect (longer vowels before voiced than voiceless obstruents, in e.g., bead vs. beat) is realized in spontaneous speech, and varies across dialects and individual speakers. Compared with previous reports of controlled laboratory speech, the Voicing Effect was found to be substantially smaller in spontaneous speech, but still influenced by the expected range of phonetic factors. Dialects of English differed substantially from each other in the size of the Voicing Effect, whilst individual speakers varied little relative to their particular dialect. This study demonstrates the value of large-scale phonetic research as a means of developing our understanding of the structure of speech variability, and illustrates how large-scale studies, such as those carried out within SPADE, can be applied to other questions in phonetic and sociolinguistic research.

Comprehension of familiar and unfamiliar native accents under adverse listening conditions.

This study aimed to determine the relative processing cost associated with comprehension of an unfamiliar native accent under adverse listening conditions. Two sentence verification experiments were conducted in which listeners heard sentences at various signal-to-noise ratios. In Experiment 1, these sentences were spoken in a familiar or an unfamiliar native accent or in two familiar native accents. In Experiment 2, they were spoken in a familiar or unfamiliar native accent or in a nonnative accent. The results indicated that the differences between the native accents influenced the speed of language processing under adverse listening conditions and that this processing speed was modulated by the relative familiarity of the listener with the native accent. Furthermore, the results showed that the processing cost associated with the nonnative accent was larger than for the unfamiliar native accent.