This paper investigates the influence of visual cues in the perception of the /r/-/w/ contrast in Anglo-English. Audio-visual perception of Anglo-English /r/ warrants attention because productions are increasingly non-lingual, labiodental (e.g., [ʋ]), possibly involving visual prominence of the lips for the post-alveolar approximant [ɹ]. Forty native speakers identified [ɹ] and [w] stimuli in four presentation modalities: auditory-only, visual-only, congruous audio-visual, and incongruous audio-visual. Auditory stimuli were presented in noise. The results indicate that native Anglo-English speakers can identify [ɹ] and [w] from visual information alone with almost perfect accuracy. Furthermore, visual cues dominate the perception of the /r/-/w/ contrast when auditory and visual cues are mismatched. However, auditory perception is ambiguous because participants tend to perceive both [ɹ] and [w] as /r/. Auditory ambiguity is related to Anglo-English listeners’ exposure to acoustic variation for /r/, especially to [ʋ], which is often confused with [w]. It is suggested that a specific labial configuration for Anglo-English /r/ encodes the contrast with /w/ visually, compensating for the ambiguous auditory contrast. An audio-visual enhancement hypothesis is proposed, and the findings are discussed with regard to sound change.

Articulatory variation is well-documented in post-alveolar approximant realisations of /r/ in rhotic Englishes, which present a diverse array of tongue configurations. However, the production of /r/ remains enigmatic, especially concerning non-rhotic Englishes and the accompanying labial gesture, both of which tend to be overlooked in the literature. This thesis attempts to account for them both by considering the production and perception of /r/ in the non-rhotic variety of English spoken in England, ‘Anglo-English’. This variety is of particular interest because non-lingual labiodental articulations of /r/ are rapidly gaining currency, which may be due to the visual prominence of the lips, although a detailed phonetic description of this change in progress has yet to be undertaken.

Three production and perception experiments were conducted to investigate the role of the lips in Anglo-English /r/. The results indicate that the presence of labiodental /r/ has resulted in auditory ambiguity with /w/ in Anglo-English. In order to maintain a perceptual contrast between /r/ and /w/, it is argued that Anglo-English speakers use their lips to enhance the perceptual saliency of /r/ in both the auditory and visual domains. The results indicate that visual cues of the speaker’s lips are more prominent than the auditory ones and that these visual cues dominate the perception of the contrast when the auditory and visual cues are mismatched. The results have theoretical implications for the nature of speech perception in general, as well as for the role of visual speech cues in diachronic sound change.

The secondary labial articulation which accompanies the post-alveolar approximant /r/ in English has attracted far less attention from linguists than the primary lingual one. However, the lips may be particularly important in the variety of English spoken in England, Anglo-English, because non-lingual labiodental articulations ([ʋ]) are on the rise. Labiodentalisation may be due to speakers retaining the labial gesture at the expense of the lingual one, implying that /r/ is always labiodental even in lingual productions. We verify this assumption by comparing the labial postures of /r/ and /w/ in Anglo-English speakers who still present a lingual component. If post-alveolar /r/ is labiodental, the labial gesture for /w/, which is unequivocally considered rounded, should differ considerably. Techniques from deep learning were used to automatically classify and measure the lip postures for /r/ and /w/ from static images of the lips in 23 speakers. Our results suggest that there is a recognisable difference between the lip postures for /r/ and /w/, which a convolutional neural network is able to detect with a very high degree of accuracy. Measurements of the lip area acquired using an artificial neural network suggest that /r/ indeed has a labiodental-like lip posture, thus providing a phonetic account for labiodentalisation. We finish with a discussion of the methodological implications of using deep learning for future analyses of phonetic data.

This paper presents acoustic and articulatory data from prevocalic /r/ in the non-rhotic variety of English spoken in England, Anglo-English. Although traditional descriptions suggest that Anglo-English /r/ is produced using a tip-up tongue configuration, ultrasound data from 24 speakers show similar patterns of lingual variation to those reported in rhotic varieties, with a continuum of possible tongue shapes from bunched to retroflex. However, the number of Anglo-English speakers using exclusively tip-up variants is higher than that reported in American English across all phonetic contexts. It is generally agreed that English /r/ may be labialised, but the exact contribution of the lips has yet to be explored. Lip camera data reveal significantly more lip protrusion in bunched tongue configurations than retroflex ones. These results indicate that the differing degrees of lip protrusion may contribute to maintaining a stable acoustic output across the different tongue shapes. An articulatory-acoustic trading relation between the sublingual space and the degree of lip protrusion is proposed. Finally, we suggest that Anglo-English /r/ has a specific lip posture which differs from that of /w/. We relate the development of such a posture to Anglo-English speakers’ exposure to labiodental variants and to the pressure to maintain a perceptual contrast between /r/ and /w/.

This paper studies the use of a lip retractor as a potential technique for phonetic studies involving perturbation. This device is currently used by participants of the internet sensation, the so-called “no lips” or “mouth guard” challenge. Wearing the device restricts the use of the lips during speech. We present acoustic and articulatory data from four speakers of British English. Accelerometer data is used to assess the dynamics of the jaw and ultrasound tongue imaging gives us insights into potential compensation strategies, specifically for the /u/ (GOOSE) vowel. Ultrasound data revealed that three speakers showed signs of tongue retraction for perturbed /u/, which was not reflected in the corresponding acoustic data. This study highlights the limitations of a purely acoustic analysis of the effects of perturbation on speech. Despite certain limitations, we conclude that the use of the lip retractor is a promising technique for future lip perturbation studies.