Differences in the time-course of accent adaptation:
A comparison of adaptation to foreign-accented and
unfamiliar regionally-accented speech.
Bronwen G. Evans1, Patti Adank2,3
1 Speech,
3
Hearing and Phonetic Sciences. University College London, UK
2 F.C. Donders Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands
Department of Cognitive, Perceptual and Brain Sciences, University College London, UK
[email protected], [email protected]
Method
Background
• Recent work demonstrates that listeners adapt quickly to
foreign-accented speech [1].
• Participants: 10 (two male) all born and raised in the south of
England and unfamiliar with Glaswegian and Spanish.
• However, it is not clear whether adaptation to an unfamiliar
regional accent operates in the same way; some studies have
shown that listeners are able to rapidly adapt to differences in
unfamiliar regionally accented speech, even when this is a
novel accent [2], whilst others have shown that listeners do not
alter their perceptual representations even when they are
highly familiar with the accent [3].
• Stimuli: IEEE sentences [5] recorded by two male speakers, a
native GE and a native SpE speaker. Sentences were
presented at a fixed SNR. As we were interested in the time
course of adaptation rather than the relative processing difficulty
per accent, the sentences were matched for overall intelligibility
using a different SNR per accent; 0.93 dB for GE, 3.11 dB for
SpE. These values were determined in a pilot study (10
participants) with the same stimuli in an adaptive speech-innoise task that established the SNR threshold for each accent
(see [3] for task details).
• The aim of this investigation was to further explore adaptation
to different accents by comparing the time course of adaptation
to an unfamiliar regional accent with adaptation to foreignaccented speech. Listeners identified sentences in noise
produced in an unfamiliar regional accent (Glaswegian; GE)
and foreign-accented speech (Spanish-accented English; SpE).
It was expected that listeners would adapt more to foreignaccented speech, given the mixed results for adaptation to
regionally-accented speech [4].
• Procedure; Participants completed a practice session of 10 SE
(Standard English) sentences. They then identified 100
sentences (50 in GE, 50 in SpE, order counterbalanced).
Intelligibility was scored by marking the number of correctly
identified keywords per sentence (max. 5).
SNRs
GE: +3.11 dB
SpE: +0.93 dB
Processing cost
• In an earlier experiment
we determined the relative
processing
cost
for
sentence verification in
three accents in four SNRs
cf. 6]: SE (Standard
English), GE, and SpE.
Participants had to verify
sentences such as “Nuns
are made in factories” as
quickly as possible (N =
16). See [6] for details.
• Results show that the
cognitive processing cost
was higher for SpE than
for GE. Second, there was
an interaction between
SNR and the speaker’s
accent between SE and
GE, but not between SE
and SpE.
Design
10 participants
50 sentences
per accent
1 speaker per
accent
Improvement
GE: 8 %
SpE: 2%
Summary of results
Conclusions
• Overall performance on GE and SpE sentences did not differ.
This indicates that our initial experiment to determine the
relative SNR thresholds for each accent was successful in
controlling for overall intelligibility.
• Listeners adapted to GE, but there was no evidence to suggest
that listeners’ performance with SpE improved. Why?
• Listeners showed a greater improvement in GE in the second
half of the sentence block than they did for SpE. For GE
sentences, listeners’ performance on the first 25 sentences vs.
performance on the second 25 sentences improved by 8%.
For SpE, performance only improved by 2%.
• The improvement for GE was significant (p < 0.05).
• Although the results for SpE trended in the correct direction,
there was no significant overall improvement.
• The phonetic and phonological differences that contribute
towards a foreign accent may be less stable. That is, the
error patterns made by a non-native speaker may be more
variable and therefore more difficult to adapt to perceptually
than the differences between different regional accents.
• Influence of the media; although our listeners did not come
into contact regularly with GE, it is possible that they were
familiar with GE through the media and that this enabled
them to adapt more quickly and successfully to the GE
speaker than to the SpE speaker.
•
0
REFERENCES
[1] Clarke, C. M. & Garrett, M.F. (2004). Rapid adaptation to foreign-accented speech. Journal of the Acoustical Society of America 116: 3647-3658.
[2] Maye, J. et al. (in press). The Weckud Wetch of the Wast: Lexical adaptation to a novel accent. Cognitive Science.
[3] Evans, B.G. & Iverson, P. (2007). Plasticity in vowel perception and production: A study of accent change in young adults. Journal of the Acoustical Society of America 121: 3814-3826.
[4 ] Adank, P. & McQueen, J.M. The effect of an unfamiliar regional accent on the speed of word processing. Proceedings of the XVIth International Congress of Phonetic Sciences, Saarbruecken, Germany, 1925-1928.
[5] Rothauser et al. (1969). IEEE recommended practice for speech quality measurements. IEEE Trans. Audio Electroacoust. AU-17 (3): 225-236
[6] Adank, P.. Evans, B.G., Stuart-Smith, J. & Scott, S.K. Comprehension of familiar and unfamiliar native accents under adverse listening conditions, under review