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.