11. Phonetics of Second and Foreign Language Acquisition

ID: 820ARTICULATORY TIMING OF THE JAPANESE SINGLETON ANDGEMINATE /t/ PRODUCED BY SPEAKERS OF STANDARD CHINESE
Maho Morimoto1, 2, Ai Mizoguchi3, 4, Li Weiyu1, Takayuki Arai1
1

Sophia University, 2JSPS, 3Maebashi Institute of Technology, 4NINJAL

maho.morimoto.jp@gmail.com, aimizoguchi@maebashi-it.ac.jp, w-li-5x4@eagle.sophia.ac.jp, arai@sophia.ac.jp

ABSTRACT
Consonant length contrast is known to be problematicto acquire for L2 learners of Japanese. Previous
studies pointed out that the difficulty in producing thecontrast can largely be attributed to the incomplete
mastery of the timing control in the target language.
In this study, we conducted an ultrasound experiment
to investigate the realization of the consonant length
contrast by L2 learners of Japanese with an L1
Standard Chinese background.
We report the results from acoustic andarticulatory analyses of the contrast between /t/ and/tː/ with special focus on the gestural duration andarticulatory timing. While certain acoustic durational
aspects of the contrast were successfully learned by
the L2 speakers examined in this study, the differencein the tongue tip gesture duration observed in thenative speakers was not present for some of thelearners. We discuss the relationship between thearticulatory and acoustic timing control.
Keywords: Japanese geminates, Standard Chinese,
L2, articulation, ultrasound.
1. INTRODUCTION
For L2 learners of Japanese, learning the quantity
contrast in the language can be problematic,
especially if their L1 does not make use of suchcontrasts [1, 2, 3]. Previous acoustic analyses of L2
productions of Japanese singletons (short consonants,
as in /kata/ ‘shoulder’) and geminates (longconsonants, as in /katːa/ ‘win-PAST’) have revealed
that issues in the realization of the contrast largely
arise due to the difficulty in controlling the durationof the segments, especially the constriction duration
which is known to be the primary perceptual cue tothe contrast [1, 4, 5]. L2 learners are often reported tounderdifferentiate singletons and geminates byproducing either geminates that are too short inconstriction duration, or singletons that are too longin duration [4, 6].
Issues in manipulating the segment duration
extend to the duration of the vowels surrounding thesingletons and geminates [4, 6]. Especially, inJapanese, vowels preceding geminates (V1) arephonetically longer than vowels preceding singletons2691[7, 8]. This can be a notable challenge for learners
with various L1 backgrounds, as it goes against thecross-linguistic tendency whereby the nucleus of aclosed syllable shortens [9].
Previous studies on the articulation of geminate
stops by native speakers of Japanese have discussed
the duration of the closure gesture and its timing as apossible cause for the phonetic lengthening of V1 [8,10]. Several studies have shown that the tongue
raising gesture at the offset of V1 is longer in duration
for geminates than for singletons [11, 12, 13, 14]. In
addition, the onset of the tongue raising gesture
relative to the acoustic onset of the consonant closure
occurs earlier in geminates than in singletons [11].
Based on these findings, it has been pointed out thatslower consonantal gestures allow for a more
articulated and prolonged production of V1 [8, 10].
While various acoustic studies have investigated
the timing control in the realization of the consonant
length contrast by L2 learners of Japanese, how the
manipulation of segmental duration is implemented
articulatorily has not been addressed directly. In thisstudy, we report on a production experiment using
ultrasound in order to investigate the lingual gestures
and their relation to the acoustic durations in the
singleton and geminate /t/ as produced by native
speakers and Chinese-speaking learners of Japanese.
2. METHODS
2.1. Participants

We recruited 10 native speakers of Standard andMandarin Chinese (CH) and 10 native speakers ofJapanese (JP). In this study, we report the results fromsix of these speakers (three from each group), as
shown in Table 1. We include three advanced learners(N1 level in the Japanese Language Proficiency Test)
identifying themselves as native speakers of Standard
Chinese (BCF01 and BCF04) or Mandarin Chinese(BCF05), and three native speakers of Japanese from
Tokyo (BJF03 and BJF06) or an adjacent area
(BJF07). All of them are female speakers in their 20s
with normal hearing and speaking ability, residing inJapan at the time of the experiment. The Standard andMandarin Chinese speakers were chosen for two
reasons. First, their L1 phonology does not allow fora non-nasal obstruent coda, thus lacking obstruent

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geminates; second, Chinese speakers constitute oneof the largest Japanese learner populations [15, 16].
Advanced learners were chosen to ensure that theylearned the consonant length distinction to someextent.
Instructions were provided in written and spoken
Japanese and Chinese as necessary, and theparticipants consented to the experimental procedure
approved by the Sophia University Committee for
Ethics. A language background questionnaire wasadministered prior to participation. They werecompensated for their participation.
Table 1: Linguistic background of the six speakers
reported in this study.

Speaker
BCF01
BCF04
BCF05
BJF03
BJF06
BJF07

Age
24
21
22
20
22
21

RegionShandong/Tianjin
Shanghai
Beijing
Tokyo
Tokyo
Kanagawa

JP level
N1
N1
N1
NativeNativeNative2.2. Speech materials

The speech materials consisted of 16 Japanese
bisyllabic words including /t/, /k/, /s/, and /ʃ/ as thetarget consonant (C2 in C1V1C2V2). The words werevaried in terms of the length of the target consonants
and lexical pitch accent, and were embedded in acarrier phrase (/korewa ___ to iːmasu/ ‘this is called___’). They were manually presented on a screen one
at a time in semi-randomized order, using Japanesecharacters (both Hiragana and Kanji). We obtained 10
repetitions for each word. For the current study, we
report the results for two words, namely, /hata/ ‘field(as a surname)’ for singletons (S), and /hatːa/ ‘crawlPAST’ for geminates (G), both of which have a falling
pitch accent.

The audio and ultrasound video were recorded andsynchronized using AAA software [18]. The frame
rate of the obtained ultrasound videos was 113 fps.
Four tokens were excluded from the analysis due tosynchronization error. Altogether, 116 tokens (2consonant length × 10 repetitions × 6 speakers, minus
the 4 excluded tokens) were subjected to acoustic andarticulatory analyses.
2.4. Analysis

Data analysis was implemented using R [19], basedon the acoustic and articulatory landmarks obtained
through the following annotation procedures.
The audio recordings were annotated using Praat[20]. The segmental boundaries were identified in the
waveform and spectrogram display based on the
periodic cycles of the vowels.
Ultrasound images were annotated using the
GetContours program [21]. Two articulatory
landmarks were identified based on the tongue tip(TT; the most anterior point of the visible tongue
contour): GestOns (onset of the TT raising gesture, orthe frame in which the TT starts to rise) and GestMax(onset of the TT maximal constriction, or the frame inwhich the TT ceases to rise). In addition, an acoustic
landmark, CloOns (acoustic onset of the consonant
closure), was imported from the Praat TextGrids. The
time difference between GestOns and GestMax was
calculated to be analyzed as the duration of the TTraising gesture, or TTGest. The duration between
GestOns and CloOns, as well as the duration between
CloOns and GestMax were calculated to examine thetiming of the TT raising gesture.
In order to evaluate the effect of consonant length
on the durational variables, we performed a linear
mixed effects model analysis [22] for each speakergroup, with consonant length (hata or hatta) as the
fixed effect and speakers as the random effect.
3. RESULTS AND DISCUSSION

2.3. Data collection

Audio and ultrasound recordings were madesimultaneously for each speaker in a soundproof
room, as they read the presented phrases aloud.
The acoustic signal was digitally recordedmonaurally at 22,050 Hz to a laptop computer
through an audio interface (Focusrite, Scarlett Solo
2nd Gen), using a RODE-NT2-A microphone.
Real-time mid-sagittal images of the oral cavity
were recorded with an ultrasound system (MicrUS,
EXT-1H) using a microconvex probe (MC10-5R10S3). The probe was placed under the participant’s chin,
and an UltraFit Headset [17] was used to stabilize therelative position of the probe and the participant’shead. The tongue images were recorded during theutterances.

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First, we confirmed through auditory impression thatthe learners’ productions of /tː/ were perceived as
geminates (see 3.3. for an acoustic analysis).
3.1. TT gestural duration

Table 2 summarizes the durational results related to
the TT raising gesture. Overall, the TT raising gesture
was longer for geminates than for singletons among
the Japanese speakers (β=24.95, t=4.53, p<.001), in
accordance with previous literature. However, thistrend was not observed among the Chinese speakers(β=4.12, t=0.9, p=0.37), suggesting that the learners
did not vary the duration of the TT raising gestureacross consonant length. Based on the view that V1

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lengthening is a by-product of the slower TT gesture
duration, these results tentatively suggest that the L2
learners in this study have not mastered the timing
control for Japanese geminates, including V1
lengthening (however, see 3.3).
In the meantime, Fig. 1 shows that the TT gesture
duration in singletons and geminates vary among thelearners. Specifically, BCF05 showed the sametendency as the Japanese speakers.

but not for the native speaker BJF03. The exceptional
behavior of BCF05 is consistent with the distinctionin the TT gestural duration, and suggests that she has
acquired the gestural timing for Japanese geminates.

Table 2: Average duration in milliseconds (sd) andgeminate-to-singleton ratios (GSR) for TTGest,
GestOns~CloOns, and CloOns~GestMax, per native
language (NL) and consonant length (L).

NL

L

n

CH

S 30
G 29

GSR
JP S 29
G 28
GSR

TTGest GestOns~CloOns
80.21
54.35(19.55) (12.27)
83.89
56.53
(21.66) (16.23)
1.05
1.04
85.41
66.57
(24.72) (18.34)
110.81 77.44(36.66) (26.21)
1.30
1.16

CloOns~GestMax
25.85(12.66)27.36(15.69)1.06
18.85(13.06)33.37(18.64)
1.77

Figure 2: GestOns~CloOns, per word and speaker.

Comparison of the CloOns~GestMax durations
reveals that overall, the TT maximal height wasachieved later for geminates among the Japanese
speakers (β=14.45, t=4, p<.001), but not among the
Chinese speakers (β=1.83, t=0.62, p=0.53). Fig. 3
shows that the covert TT raising gesture continued
after the acoustic onset of the consonant, and its
duration was slightly longer for geminates than for
singletons in native speakers.

Figure 3: CloOns~GestMax, per word and speaker.

Figure 1: TTGest duration per word and speaker.
3.2. TT gestural timing

A similar trend is observed in the timing of the TTraising gesture relative to the acoustic onset of theclosure. While the duration for GestOns~CloOns
differed significantly for singletons and geminates
among the Japanese speakers (β=10.52, t=2.34,
p<.05), no such difference was observed among the
Chinese speakers (β=2.2, t=0.6, p=0.55). The trend
among the Japanese speakers conforms to thefindings in [11], in that there was a greater overlap
between V1 and the TT raising gesture for geminates
than for singletons. On the contrary, the timing withwhich the Chinese speakers initiated the TT raisinggesture was the same across consonant length.
Fig. 2 again shows some interspeaker variability,
but this time for both speaker groups. Early gestural
onset for geminates was observed in learner BCF05,

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The difference was the largest for BJF03 (3.94
times longer for geminates on average), suggestingthat the timing of the TT raising gesture onset in her
geminate productions was no different from that ofher singletons, but that completing the gesture tookmuch longer. While BJF03’s tendency deviates fromthose of the other Japanese speakers reported in thisstudy, some variability in the timing control for
geminates among native speakers has been previously
reported [10]. Once a fuller analysis with more
Japanese speakers is implemented, it may provide an
insight into the typology of L1 articulatory strategies
for the consonant length.
3.3. Acoustic duration

Table 3 summarizes the acoustic durations. The firstpoint to note is the considerable difference in theoverall speaking rate between the two groups, as11. Phonetics of Second and Foreign Language Acquisition

ID: 820

exemplified in the word duration (β=–280.48, t=–16,
p<.001). Second, the acoustic results reveal that the
Chinese speakers in this study were able todifferentiate singletons and geminates in theirproductions at the segmental level. The geminate-tosingleton ratios for each segment were largely in linewith those of the native speakers, and their C2/Wordratios, known to have high classification accuracy atthe boundary ratio of 0.35 [23], were 0.33 forsingletons and 0.46 for geminates.
Table 3: Duration in milliseconds (sd) and geminateto-singleton ratios (GSR) for word, V1, C2, and V2 pernative language (NL) and consonant length (L).

NL
CH

L n Word
S 30 489.53(49.79)G 29 663.86(62.43)
GSR
1.36
JP S 29 249.29(30.09)G 28 341.21(45.39)
GSR
1.37

V1
51.3
(9.67)
64.77(14.2)
1.26
47.92(9.79)
67.42(10.4)
1.40

C2
159.83(22.26)309.72(66.52)
1.94
82.05(15.56)161.13(27.24)
1.96

pattern is reminiscent of the over-exaggerated
geminates in L2 speech reported in [1]. The slower
speaking rate and the V1 lengthening effect suggestthat TT gesture duration was short for Chinese
speakers.

Figure 5: Bar chart for average segment duration.

V2
141.96(29.68)171.88(35.84)
1.21
60.1(9.33)
50.74(8.13)
0.84

4. CONCLUSION

In addition, the learners have acquired the pregeminate V1 lengthening (CH: β=13.12, t=5.54,
p<.001; JP: β=19.24, t=7.32, p<.001). This was
unexpected given our findings on the TT gesture
duration. However, not only the native speakers andBCF05, the exceptional learner, but also the other two
Chinese speakers with a shorter TT gesture duration
have mastered pre-geminate V1 lengthening (Fig. 4).

Figure 4: V1 duration per word and speaker.

Meanwhile, although clear segmental distinctions
were made by the learners, some of the durationalcorrelates were not adequately acquired, as illustrated
in Fig. 5. For example, the slight shortening of V2
among the Japanese speakers (β=–9.58, t=–5.2,
p<.001) was not shown by the Chinese speakers.
Rather, those learners lengthened V2 after geminates(β=29.87, t=4.31, p<.001). Furthermore, the ratio of
the acoustic closure duration and V1 duration was
strikingly different between the two groups. This

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The duration and timing of the TT raising gesture in
the singleton and geminate /t/ were investigated, in
relation to the acoustic segmental durations. Results
showed that while native speakers of Japaneseemployed a longer TT raising gesture for geminates
than for singletons, such an articulatory distinction
was not made by the Chinese speakers except for one(BCF05). In addition, while the TT raising gesture
started early relative to the acoustic consonantal onset
in geminates for two out of the three Japanese
speakers and the learner BCF05, that was not the casefor the other two Chinese speakers and the otherJapanese speaker (BJF03). This suggests that it ispossible for the learners to acquire the gestural timing
control for Japanese geminates, and that there may besome interspeaker variability among native speakers.
In the meantime, the acoustic V1 lengthening in
geminates was seen robustly across speaker groups.
While this can be accounted for by the highproficiency of the speakers included in the current
analysis, it also shows that it is possible for advanced
learners of Japanese with an L1 Chinese backgroundto manipulate the segmental duration to realize theperceptually relevant acoustic distinction, even
without acquiring a native-like gestural timing. Thisfinding is in support of the view that learners employ
different strategies from that of native speakers toachieve timing control, possibly governed by adifferent rhythmic unit [4, 6, 8].
How the distinction is achieved articulatorily
should be addressed in more details in future research.
In particular, this study focused on the TT gesture ofa limited number of advanced learners. Further
analysis should include the articulation of the tongue
as a whole, in more tokens produced by learners withvarious proficiency levels. Of special interest is the
tongue positions during V1, to address the magnitude
of articulatory gestures before geminates and theirrelation to gestural duration.

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5. ACKNOWLEDGMENTS
This study was supported by JSPS KAKENHI Grant
Numbers JP19K13254, JP22J01381, JP23K12212,
and Sophia University Special Grant for Academic
Research (Research in Priority Areas). We thank theanonymous reviewers for their comments.
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