/u/-fronting in RP: a link between sound change and diminished perceptual compensation for coarticulation?

Jonathan Harrington, Felicitas Kleber, Ulrich Reubold

General aim of this paper

To establish whether a sound-change in progress, /u/-fronting in Standard Southern British (SSB) – can be linked to diminished perceptual compensation for coarticulation (Ohala, 1993).

Standard Southern British English = 'BBC English' = mainstream Received Pronunciation (Wells, 1982), spoken by the majority of speakers with a standard accent in England.

/u/ (lexical set GOOSE) has become fronted in the last 50 years (various e.g., Wells 1982, Henton 1983, Deterding 1997, Harrington et al. 2002, Harrington 2006, Hawkins & Midgley 2005, Roach, 1997).

/u/-fronting and speech production1. Taking into account word-frequency, in /ju:/-dialects like SSB ('duty' = /dju:ti, du:ti/), /u/ is preceded by C with a high F2-locus (e.g. /j/ in 'cute', /s/ in 'soon') roughly 70% of the time (Harrington, Labphon 9, in press).

2. In acoustic analyses of the Queen's Christmas broadcasts, the extent and rate of F2 transition in /Cu:/ progressively diminished over 50 years – suggesting a link between increased C-on-/u:/ coarticulation and a sound change in progress. (N.B. there is no evidence for a waning of the formality of speaking style in the Christmas broadcasts, as e.g. Harrington et al, 2005 show).

So from the point of view of speech production: perhaps there is coarticulatory pressure on /u/ to front?

/u/-fronting and speech perception

…not only the speaker, but also ''the listener as a source of sound change'' (Ohala, 1981)

Ohala (1993): hypoarticulation-sound changes are those in which a listener fails to undo the effects of coarticulation.

Our extension of Ohala's model to these data and age-differences in SSB speakers is as follows:

/u/-fronting and speech perception

Acoustic input: [sn]

compensate for coarticulation

Perceived as: /sun/ /sn/

OLD listeners YOUNG listeners

Method: synthetic continua

We used HLSYN to create two 13 step synthetic /i-u/ continua at equal Bark intervals by varying F2 in two sets of minimal pairs :(a) /jist/ --- /just/ YEAST---USED (p. tense)(b) /swip/ --- /swup/ SWEEP---SWOOP

A separate group of listeners verified that the endpoints of the continua could be correctly identified.

Stimuli randomised and both continua presented in one session 5 times (5 x 13 x 2 = 130 randomised stimuli).

Forced-choice identification task: Subjects responded with one of ''used'', ''yeast'', ''swoop'', ''sweep'' to each stimulus.

30 Standard Southern British speakers recruited through University of Cambridge and University College London.

YOUNG: 14 subjects aged 18-20 (11 F, 3 M)

OLD: 16 subjects aged 53-88 (7 F, 9 M)

Method: Subjects

Subjects were carefully checked to ensure that they were SSB speakers.

Some acoustic data to illustrate /u/-fronting in the young group

female

male

Three predictions concerning the responses to the synthetic stimuli

Prediction 1. Age differences (young vs. old)

Prediction 2: Word-type (yeast-used vs. sweep-swoop).

relates to Mann & Repp (1980)

Prediction 3: Age x Word-type interaction

relates to Ohala (1993)

Prediction 1. AGESince young listeners have a fronted /u/ in speech production, they will have a greater proportion of /u/-responses to the continua that older listeners (because ambiguous tokens between synthetic [i] and [u] will tend to be perceived as /u/ by the young).

So the hypothesis is that YOUNG and OLD differ not just in production but also in perception

Prediction 2: Word-type

Independently of age, /i-u/ boundary should be LEFT-SHIFTED (= more /u/ responses) in YEAST-USED because listeners compensate for coarticulation, e.g. Mann & Repp, 1980)…

= the probability of hearing /u/ for the SAME stimulus is greater in YEAST-USED because listeners attribute a certain degree of F2-raising to the effects of the anterior /j_s/ context and factor this out i.e. bias their responses towards /u/

Prediction 3: Age x Word-type

IF following our extension of Ohala's model, /u/-fronting comes about because young listeners compensate less for the effects of /C/-on-/u:/ fronting, then the difference in the responses to YEAST-USED vs. SWEEP-SWOOP should be less for the YOUNG

because, if there is no/limited compensation for coarticulation, the young will tend not to bias their responses in YEAST-USED towards /u/.

Results (1): AGE

The /i-u/ boundary is significantly left-shifted (greater proportion of /u/ responses) in YOUNG compared with OLD speakers.

Results 2: Word-type

Significantly greater proportion of /u/ responses (across both age groups) in YEAST-USED relative to SWEEP-SWOOP (compatibly with Mann & Repp, 1980).

Results 3: Age x Word-type

The difference in the responses between YEAST-USED vs. SWEEP-SWOOP was less for YOUNG (left) than OLD (right).

Our interpretation: less perceptual compensation for coarticulation in the YOUNG.

Summary: replication/support for three findings/theories

confirmation that /u/-fronting is a sound change in progress in SSB both from acoustic and perception data

further confirmation that listeners compensate for coarticulation (Mann & Repp, 1980)

evidence that sound change is also in the ear of the listener (Ohala, 1993)

Conclusions: new findings.

2. We have linked Ohala's model to sound-change in progress by showing that young listeners do not undo the effects of coarticulation to the same extent as older listeners.

1. In the case of age-graded sound-change in progress, young and older members of the same speech community differ not just in production but also in perception

Research support by the German Research Council. Our thanks to Sarah Hawkins and the Dept. of Linguistics, Cambridge University and to Moira Yip, UCL for helping us find subjects and for letting us run the experiments in their laboratories.