PTLC2005 Geoffrey Schwartz
Phonetics-phonology interface – implications 1
The phonetics-phonology interface – implications
for teaching L2 pronunciation
Geoffrey Schwartz
Adam Mickiewicz University, Poznań, Poland
1 Introduction The phonetics-phonology interface (see e.g. Hume and Johnson,
2001), examining the role of acoustic and perceptual phenomena in the shaping and
maintenance of phonological contrasts, is a “hot” topic in current linguistic research.
At the core of this interface lies the fundamental issue of how continuous phenomena
found in the acoustic speech signal are represented in speakers’ discrete mental
representations of linguistic units. At present, this area represents largely uncharted
waters in the field of foreign language pedagogy. Pronunciation teachers and
textbooks tend to rely on static phonological labels, symbols of “phonetic”
transcription that provide useful reference points, but make it easy for teachers and
students to overlook the dynamic aspects of speech that are so crucial to
comprehension. This paper reports on three experiments investigating how
pronunciation teachers might benefit by approaching their jobs from the point of view
of speech perception - concentrating on the dynamic nature of the acoustic speech
signal. Each experiment was carried out with Polish students of English, and deals
with the long/short contrast in English high vowels (e.g. infamous pairs such as ship
and sheep), a problematic area for many foreign learners. Before reporting on the
individual experiments, it is worth providing a quick illustration of some acoustic
phenomena associated with this contrast.
2 The phonetic anatomy of a binary contrast The vowel contrast in the pair of
English words seat and sit is generally considered a binary phonological opposition,
characterized as either long v. short or tense v. lax. Although for the purposes of
phonemic analysis seat and sit represent a minimal pair, an acoustical investigation
may reveal differences in several phonetic parameters between the two vowels.
5000
1
3
0
1 .5 4 2 6 3
2
400
4
100
0
1 .5 4 2 6 3
T im e ( s )
Figure 1 – Spectrogram and pitch track for English seat (left) and sit. Arrows point to
various acoustic parameters discussed in Section 2.
PTLC2005 Geoffrey Schwartz
Phonetics-phonology interface – implications 2
Figure 1 presents a spectrogram and pitch track of the words seat and sit as
produced by a native speaker of English. The two tokens were recorded in carrier
sentences to control for phonetic and prosodic context effects. The numbers on the
spectrograms point to four different acoustic phenomena by which the two vowels
differ. The first arrows (numbered 1) point to the first and second formants, which at
first glance show a more peripheral articulation target (higher, more fronted tongue
position) for the seat vowel. However, a closer look at reveals an important dynamic
phenomenon associated with the contrast. We can notice in the seat vowel that there
is much more formant movement, betraying it’s diphthongal nature. Arrow number
two indicates the longer duration of the seat vowel. The third arrow points to the area
of the spectrum between the first and second formants. Notice that in the sit vowel,
there is significant harmonic energy in this frequency range, while in the seat vowel
there is almost none. This is a reflection of a difference in voice quality between the
two vowels – the seat vowel is characterized by more breathy phonation while the sit
vowel is produced with a creakier voice quality. Finally, arrow 4 pointing to the pitch
track indicates that despite the fact that these tokens were produced in identical
prosodic positions, the seat vowel is marked by more dramatic movement in pitch
than the sit vowel. Table 1 summarises these and other acoustic phenomena that
were measured for these tokens, showing that the binary long/short vowel contrast is
realized on the basis of several phonetic parameters.
Parameter
Overall amplitude
seat
70dB
sit
75dB
Duration
160ms
120ms
Average F1-F2
295 Hz-2498 Hz
438 – 2059 Hz
Range of movement F1 275-304 Hz
in F1 and F2.
F2 2362-2645 Hz
F1 386-449 Hz
F2 1979-2123 Hz
Relative amplitude of 49.6 dB H1
first two harmonics
36.3 dB H2
41.4 dB
51.2 dB
Overall amplitude of 49.8 dB
3rd – 9th harmonics2
combined
68.6 dB
Pitch range
209-199 Hz.
226-186 Hz
comments
more closed vowel
generally
lower
in
amplitude
A “standard” parameter
of the
associated with the
contrast
Difference
in
articulatory target.
More peripheral for
seat
very large (and slow)1
F2 movement for seat,
showing
vowel’s
diphthongal quality
Strong
fundamental
associated
with
breathier phonation in
seat
Energy
in
higher
harmonics typical of
creakier phonation for
sit
greater pitch movement
on long vowel
Figure 2 – Summary of acoustic differences between the vowels in the tokens of seat
and sit shown in Figure 1.
3 Experimental Studies To investigate the benefits of such an approach to second
language pronunciation teaching, this paper reports on three experiments dealing
1
The approach to the F2 target took 100 ms, more than half of the duration of the vowel,
perhaps the most telling statistic of the diphthongality of the seat vowel.
2
This measurement was taken after band-pass filtering the signal in the range that
corresponded to the harmonics between F1 and F2.
PTLC2005 Geoffrey Schwartz
Phonetics-phonology interface – implications 3
with Polish students’ production of the long/short (tense/lax) contrast in English high
vowels.
3.1. Experiment 1: This experiment (written up in Schwartz, 2004) investigates the
role of voice quality in native speakers’ perception of the contrast as produced by
foreign learners. Eight native speakers of American English were asked to rate 5
different Polish students’ productions of the minimal pairs seat and sit. At the same
time, measurements were taken of the same productions to rate each student’s
contrast acoustically in three parameters: Tongue position (F1F2), Duration, and
Voice Quality. These acoustic ratings aimed to describe the distinctiveness of
students’ contrasts for each acoustic parameter. They were calculated by taking the
difference in the relevant acoustic parameters between the two vowels (F2/F1 for
tongue position, amp f0 – amp H2 for voice quality, and duration). These results are
summarized in Table 2 below, showing acoustic contrast measures for the three
parameters, as well as for a native speaker. The ranking according to listeners’
ratings is presented in Table 3.
Speaker
Tongue position
Voice Quality
Duration
Alicja
4.9
11.2
1.37
Anna
3.1
14.5
1.39
Ewa
3.2
8.1
1.13
Ola
3.0
7.2
1.07
Julia
2.2
3.2
1.12
Native
4.8
17.6
1.10
Table 2 - Contrast measures for the five students’ productions and one native production of
the English tense-lax contrast
Listeners' Ranking
Speaker name
1
Anna
2
Alicja
3
Ewa
4
Ola
5
Julia
Table 3 – Native listeners’ ranking of students based on average ratings for all listeners.
3.2 Experiment 2: This experiment (written up in Schwartz and Glogowska, 2004)
was designed to test the teachability of the non-distinctive features of voice quality,
amplitude, and pitch movement. Four Polish students of English were recorded
before and after a 90-minute instructional session devoted to the three features in
maintaining the long/short contrast. The recordings were then presented to 18
teachers of English. The teacher-listeners (half of them native speakers) heard
improvements in 48.6 % of the tokens. The student subjects also reacted positively,
and were all in agreement that these features made it easier to perceive and produce
this difficult contrast.
3.3 Experiment 3: This experiment (see Schwartz, to appear) tested the role of pitch
movement in students’ production of English long high vowels. The pitch contours of
productions of these vowels were manipulated to native-like norms for utterance
PTLC2005 Geoffrey Schwartz
Phonetics-phonology interface – implications 4
prominent syllables, and presented to 21 teacher-listeners with a forced-choice task.
The results are presented in Table 4, showing that the manipulated tokens were
heard as improved at a higher than chance level.
Word Set
“Greetings”
Manipulated
has better
total # (%)
8 (38,1%)
token
vowel-
Original token has
better vowel- total #
(%)
1 (4,8%)
Neither has better
vowel- total # (%)
12 (57,1%)
“Luke”
10 (47,6%)
2 (9,5%)
9 (42,9%)
“Leave”
9 (42,9%)
6 (28,6%)
6 (28,6%)
“cheeks”
8 (38,1%)
7 (33,3%)
6 (28,6%)
“Luke”
8 (38,1%)
2 (9,5%)
11 (52,4%)
“deed”
10 (47,6%)
6 (28,6%)
5 (23,8%)
“Luke”
8 (38,1%)
4 (19,0%)
9 (42,9%)
“cheeks”
12 (57,1%)
5 (23,8%)
4 (19,0%)
Overall
73 (43,5%);
33 (19,6%)
62 (36,9%)
t=4.13, p<0.005
t=3.63, p<0.005
t=0.72, p>0.1
Table 4 – Results of Experiment 3.
4 Discussion These experiments seek to address two primary questions: 1) do
“subfeatural” parameters associated with the contrast play a role in the listeners’
perception of L2 speech as being “native-like”? 2) From the pedagogical perspective
is it possible to teach such parameters? The results of Experiments 1 and 3 indicate
that subfeatural phonetic phenomena such as voice quality and pitch movement may
be specified in speakers’ representations of segments, underlying the importance of
such features in “native-like” production. At the same time such findings lend support
to a usage-based model of phonology (Bybee, 2001). Assuming a usage-based
model might have significant implications for SLA in that it would promote the role of
variation in the language learning process, a notion that may prove troublesome for
proponents of proposals that try to simplify the task of learning English pronunciation
(Jenkins, 2000). At the same time, Experiment 2, while limited in scope, did have one
important pedagogical finding: features such as pitch movement and voice quality,
because they are concrete acoustic phenomena that students may imitate, are in
principle quite teachable.
References
Bybee, J. (2001) Phonology and Language Use. Cambridge: Cambridge University
Press.
Hume, E and Johnson, K (2001) The role of speech perception in phonology. San
Diego: Academic Press.
Schwartz, G (To appear) Pitch movement and the realization of English vowels.
Schwartz, G. (2004) Voice quality in students’ production of the English tense/lax
contrast. In Sobkowiak, W, Waniek-Klimczak, E (eds.) Dydaktyka fonetyki języka
obcego. Zeszyty Naukowy PWSZ w Koninie 1(4), 75-79.
Schwartz, G and Głogowska, M (2004) Acoustic tools for students’ production of
English long (tense) vowels. In Sobkowiak, W, Waniek-Klimczak, E (eds.) Dydaktyka
fonetyki języka obcego. Zeszyty Naukowy PWSZ w Koninie 1(4), 80-85.