PTLC2013
London, 8–10 August 2013
THE RELATIONSHIP BETWEEN VOWEL PRODUCTION AND
PERCEPTION: ADVANCED GERMAN LEARNERS’ PERCEPTION
OF NATIVENESS IN LOT AND THOUGHT VOWELS IN RP
Jussi Wikström
University of Cambridge, UK
jussiwikstrom@hotmail.com
ABSTRACT
This study sheds light on the range of variation
found in F1 for the English LOT and THOUGHT
vowels in advanced German learners of English. It
looks at the range of variation in F1 which such
learners regard as native-like for a Received
Pronunciation (RP) accent and the degree of
overlap between the learners’ LOT and
THOUGHT vowels and the vowel-qualities which
they consider RP-like. Seven 18-25-year-old
advanced German learners did a production task
and a perception test. There was no strong overlap
between the participants’ performance in the
production and perception tasks. The findings
suggest that the learners’ production of the
THOUGHT vowel was influenced by General
American English (GA) pronunciation and that
they did not rely primarily on vowel height as an
acoustic cue when judging the quality of the LOT
vowel.
LOT vowel where F1 varied between 541 Hz (5.27
Bark) and 758 Hz (6.95 Bark) as native-like and
tokens of the THOUGHT vowel where F1 was
between 381 Hz (3.83 Bark) and 513 Hz (5.03
Bark) as native-like. Thus the Thus the findings
from that study suggest that a substantial degree of
variation in vowel quality is found in L1 speech
production and native speakers regard a range of
realisations as native-like. It should be pointed out
that the LOT and THOUGHT vowels also differ in
terms of vowel duration and roundedness.
Figure 1: The LOT and THOUGHT tokens with the
highest and lowest F1 values in the L1 speaker data in
[10].
THOUGHT
Keywords English learning, native German,
pronunciation, perception.
1. BACKGROUND
LOT
Wikström [10] found that, where female L1
speakers of RP or near-RP are concerned, F1 is
used consistently to distinguish between the RP
LOT and THOUGHT vowels. F1 varied between
615 Hz (5.87 Bark) and 725 Hz (6.71 Bark) for the
LOT vowel and between 415 Hz (4.15 Bark) and
551 Hz (5.35 Bark) for the THOUGHT vowel [10];
the F1 and F2 of the LOT and THOUGHT vowels
with the highest and lowest F1 values are shown in
Figure 1. Liu and Kewley-Port [3] established that
a formant change of 0.37 Bark is sufficient for
listeners to perceive a change in vowel quality
where vowels are presented in phrases or sentences.
Moreover, Wikström [10] showed that L1 speakers
of RP or near-RP generally perceived tokens of the
However these factors are not addressed in detail
in the present study. Studies looking at L2
learners’ ability to correctly categorise L1 and L2
accents in their L2 have had mixed results. For
example, Wilkerson [12] found that L2 learners
who studied their L2 at university were typically
successful in detecting L2 accents of speakers who
shared their L1 as well as in categorising L1
accents as such. However, Scales, Wennerstrom,
Richard and Wu [8] found that advanced L2
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learners of English who had lived in the United
States for several years and studied there were
generally unsuccessful in identifying an L1
American English accent. This paper sheds more
detail on this issue by looking at the specific range
of variation in F1 in the LOT and THOUGHT
vowels which advanced German learners of RP
associate with RP. While distinguishing between
the LOT and THOUGHT vowels in RP is unlikely
to be particularly problematic for German learners
looking at these vowels seems appropriate for this
study as its emphasis is on which vowel qualities
are associated specifically with RP
Studies which have examined the relationship
between L2 speech production and perception have
had varied results. Studies such as Neufeld [5]
indicate that L2 learners’ performance in speech
perception develops faster than their performance
in production. However, Wikström and Setter [11]
found that L1 English-speaking speech and
language therapy (SLT) students were more
successful in producing cardinal vowels than in
identifying them. This paper considers how
advanced German learners’ production of the RP
LOT and THOUGHT vowels overlaps with their
perception of native-like vowel qualities. This is of
interest as previous studies have focussed on the
degree of overlap between production and
perception in maintaining L2 phonemic contrasts
or relating perceived ideal vowel quality to
production.
2. METHOD
Seven 18-25-year-old female German advanced
learners of English were recruited. The seven
participants were students of English at the
University of Stuttgart, Germany who were taught
RP pronunciation at university. English students at
the University of Stuttgart were chosen as
university students of English in Germany
typically aim mostly at an RP or GA accent (Jilka,
personal communication) and are advanced
learners of English. Only learners whose sole L2
was English were recruited to the study but
beginner-level proficiency in another L2 was
disregarded.
A Microsoft PowerPoint presentation was used
as a prompt in the production tests. The words and
corresponding phonemic transcriptions in the
production test were: heed /hiːd/, Keith /kiːθ/,
head /hed/, Etty /ˈeti/, had /hæd/, cat /kæt/, hard
100
/hɑːd/, cart /kɑːt/, cot /kɒt/, odd /ɒd/, caught
/kɔːt/, awed /ɔːd/, who’d /huːd/ and coot /kuːt/.
Synthesised tokens of words including the LOT
and THOUGHT vowels were produced for the
perception test. A phonetically trained female
speaker of near-RP was recorded in a quiet
room saying the words cot and caught using a
falling intonation. Praat speech analysis software
[1] was used to analyse the phonetic properties of
these tokens.
Akustyk software [7] was used to create
synthesised tokens of cot and caught which
involved the manipulation of F1 and F2 in 13
auditorily equidistant stimuli in order to create a
continuum of stimuli with F1 varying between 381
Hz (3.83 Bark)and 758 Hz (6.95) Bark and F2
varying between 705 Hz (6.56 Bark) and 1041 Hz
(8.77 Bark).
Table 1: This is an example of a table showing
Decibel (dB) ratios.
ratio
1/1
2/1
3.16
1/10
10/1
100/1
1000/1
Decibels
0
6
10
-20
20
40
60
A Microsoft PowerPoint presentation was designed
for presenting the stimulus material to participants.
Each slide included a sound file and the question
‘How would you rate this pronunciation of‘word’?’
and the alternatives provided were consistently ‘1.
Produced by a native speaker of Standard British
English (RP)’,‘2. Close to a native Standard British
English (RP) speaker’s pronunciation, but slightly
odd’, ‘3. Clearly not a native Standard British
English (RP) speaker’s pronunciation, but still
fairly appropriate for this word’ and ‘4. Seriously
different from a native Standard British English
speaker’s pronunciation, the word might sound as
if it could be another English word’. Each stimulus
was presented three times.
The participants were recorded while saying the
words in the production test PowerPoint
presentation. A Marantz PMD 671 recorder and
Shure SM48 cardioid dynamic microphone were
used and the data were recorded at a sampling rate
of 44.1 kHz with the signal being quantised at 16
bit. After this the participants did the perception
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test. The participants were told they could play
each sound file three times.
The production data were analysed using Praat
[1] as described earlier in this section. The
Freeman-Halton extension of Fisher’s exact test
was used to test whether any difference in the
distribution of participants’ responses was
statistically significant for two-rows by fourcolumns contingency tables by using the relevant
Vassar Stats calculator [4].
3. RESULTS
The participants’ F1 varies between 607 Hz (5.81
Bark) and 799 Hz (7.23 Bark) for the LOT vowel.
For the CAUGHT vowel, F1 varies between 400
Hz (4.01 Bark) and 719 Hz (6.67 Bark).
The Freeman-Halton extension of Fisher’s
exact test revealed no statistically significant
difference in dispersion of selections relating to
any adjacent cot stimuli in the perception test. All
options seem to be selected with an approximately
similar frequency for all cot stimuli. As such the
participants did not reliably judge any part of the
continuum of cot stimuli as native-like.
With regards to caught, the participants seem to
prefer option 1 associated with native-like
pronunciation more for five stimuli where F1 is
between 381 Hz (3.83 Bark) and 485 Hz (4.79
Bark) compared to the remaining nine stimuli
where F1 is between 513 Hz (5.03 Bark) and 758
Hz (6.95 Bark). Statistical analysis using the
Freeman-Halton extension of Fisher’s exact test
does not however reveal a statistically significant
difference in the dispersion of selections between
the stimulus whose F1 is 485 Hz (4.79 Bark) and
the stimulus whose F1 is 513 Hz (5.03 Bark).
There is however a statistically significant (p<.05)
difference between the stimulus whose F1 is 458
Hz (4.55) Bark and the stimulus whose F1 is 513
Hz (5.03 Bark). As the Freeman-Halton extension
of Fisher’s exact test suggests that the difference
between the participants’ selections between the
stimulus whose F1 is 458 Hz (4.55 Bark) and the
stimulus whose F1 is 485 Hz (4.79 Bark) is greater
than that between the stimulus whose F1 is 485 Hz
(4.79 Bark) and the stimulus whose F1 is 513 Hz
(5.03 Bark) it can be concluded that tokens where
F1 is between 381 Hz (3.83 Bark) and 485 Hz
(4.55 Bark) are generally pronunciation for those
stimuli, i.e. they are judged native-like 17 20 times
out of a possible 21, while the stimuli whose F1 is
485 Hz (4.79 Bark) is judged native-like 11 times
and the stimuli whose F1 is 513 Hz (5.03 Bark) is
judged as native-like 8 times.
Turning now to the relationship between speech
production and perception, as noted above the
participants did not consistently judge any cot
stimuli as native-like. However, F1 only varies
between 607 Hz (5.81 Bark) and 799 Hz (7.23
Bark) in production which shows that their
performance in the production and perception tasks
does not appear to correlate. Where the caught
stimuli are concerned it was established that
stimuli whose F1 is between 381 Hz (3.83 Bark)
and 485 Hz (4.55 Bark) are generally regarded as
native-like. However, F1 in the production test
varies between 400 Hz (4.01 Bark) and 719 Hz
(6.67 Bark). The participants’ THOUGHT vowels
do not therefore consistently overlap with those
vowel qualities which they associate with RP-like
THOUGHT in the perception test.
4. DISCUSSION
It is surprising that there is so much variation in the
THOUGHT vowel with variants with F1 values
similar to those associated with the RP LOT vowel
being used in many cases not least considering that
there is a distinction between back rounded vowels
with similar F1 values to those associated with RP
LOT and THOUGHT in German [2, 6]. The most
likely explanation seems to be that some
participants are influenced by the General
American English THOUGHT vowel which is
closer to the RP LOT vowel in quality [9]. This
would suggest that interference from another L2
accent may be a significant factor for advanced L2
learners and may need to be taken into account in
L2 teaching.
The participants’ more consistent performance
on the LOT vowel in production may be because
the difference in rounding between the RP and GA
LOT vowels is more salient and thus the RP-like
quality is more likely to be adopted when a
decision is made to aim at an RP accent in
particular.
In perception, the participants failed to
categorise any of the stimuli with the LOT vowel
reliably as native-like. This is also of interest
because there is a distinction between a vowel
similar to the RP LOT vowel and a vowel similar
to the RP THOUGHT vowel where F1 is
concerned in the learners’ L1 [2, 6]. It seems
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probable that this is because the L2 learners in this
study find vowel duration and roundedness to be
more important in identifying the LOT vowel than
vowel height. This is presumably due to a lack of
metalinguistic information about this vowel and
underlines the need for sufficient exposure to a
target L2 accent for appropriate perceptual
representations to be formed.
It is interesting that the participants produce
LOT vowels similar to those associated with RP
[10] and that this is not reflected in the perception
task where no stimuli are clearly judged to be
native-like. This could be because the German
learners associate the short RP LOT vowel with the
back rounded German vowel which is fairly
similar to the RP LOT vowel rather than the
German vowel which is close to the RP
THOUGHT vowel because the more open vowel is
phonemically shorter in both German and RP.
The findings relating to the THOUGHT vowel,
which suggest that the participants identified closer
qualities of the vowel as RP-like while
considerably more open vowel qualities were used
in the production test, agrees with the substantial
body of work in the literature where a perception
lead over production in L2 speech learning is
reported [5].
5. REFERENCES
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computer (Version 5.0.11) [Computer software] Downloaded
March 2008 http://www.praat.org/
[2] Hawkins, S., Midgley, J. 2005. Formant frequencies in
RP monophthongs in four age groups of speakers. JIPA 35,
183-199.
[3] Liu, C., Kewley-Port, D. 2004. Vowel formant
discrimination in high-fidelity speech. J. Acoust. Soc. Am. 116,
1224-1233.
[4] Lowry, R. 2001-2011. Fisher exact probability test 2x4.
[Online resource] Accessed June 2011
http://faculty.vassar.edu/lowry/fisher2x4.html
[5] Neufeld, G.G. 1988. Phonological asymmetry in secondlanguage learning and performance. Language Learning 38,
531-559.
[6] Pätzold, M., Simpson, A. P. 1997. Acoustic analysis of
German vowels in the Kiel corpus of read speech.
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[7] Plichta, B. ND. Akustyk (Version 1.8) [Computer
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http://bartus.org/akustyk/downloads.php
[8] Scales, J., Wennerstrom, A., Richard, D., Wu, S. H. 2006.
Language learners’ perceptions of accent. TESOL Quarterly
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[9] Wells, J.C. 2008. Longman Pronunciation Dictionary.3rd
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[10] Wikström, J. In press. The relationship between vowel
production and perception: Native speakers’ perception of
nativeness in LOT and THOUGHT vowels in RP. English
Today.
[11] Wikström, J., Setter, J. 2011. Speech and language
therapy (SLT) students’ production and perception of cardinal
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[12] Wilkerson, M.E. 2010. Identifying accent in German: a
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