Weakening patterns of intervocalic voiced plosives in JapaneseResults

12,31,41
Weiyu Li , Ai Mizoguchi , Maho Morimoto , Takayuki Arai
1Sophia University, 2NINJAL, 3Maebashi Institute of Technology, 4JSPS
This study was supported by Sophia University Special Grant for Academic Research(Research in Priority Areas) and JSPS KAKENHI Grant Numbers JP22KJ2752, JP19K13254,
JP23K12212.

• ⓪ With burst pattern

Background• ① Voiced glide pattern ➡
involves the complete absence ofburst with sustained vocal foldvibration①-1Research Questions• Voiced plosives/b//d//g/ have been observed to exhibit weakened burst•
Whatpronunciation
patternsexist• ② Voiced frication pattern➡ • ③ Pattern with halted vocal foldintensity, and in some instances, they may show a complete weakening withfor the weakening of plosive
includes frication weakening
vibration and weak aspiration ➡
no observable burst.
of burst with sustained vocal
arises from frication weakening ofconsonants in Japanese?
• Maekawa (2018) investigated the weakening rate of voiced plosives infold vibration
burst with incomplete vocal foldJapanese and its relationship with surrounding acoustic environments, using • What articulatory movements arevibration
the Corpus of Spontaneous Japanese (CSJ).
producing these weakening
patterns?
• His study revealed a notable tendency for consonant weakening, particularly• Japanese plosives : /p//b/,/t//d/, /k//g/

at positions characterized by weak prosodic boundaries.

Methods
Participants & Stimuli• Participants: 9 native Japanese speakers
Table 1: Participants
Speaker

Gender

AgeRegion

CJF01
CJF03
CJF04
CJF05
CJF06
CJF07
CJM01
CJM02
CJM03

FF
F
F
FFMMM18201921222125
20
20

Kanagawa
Fukushima/TokyoAichi/Melbourne/Chiba
Shizuoka/TokyoTokyo
Kanagawa
TokyoTokyo
Singapore/TokyoAnalysis• Acoustic analysis: 540 tokens (3 consonant × 10 repetitions ×2 pitch accents × 9 speakers) were segmented using Praat andclassified according to the weakening patterns.
• Ultrasound image analysis:I.

/ada/ & /aga/ were analyzed (250 tokens total).

II.

The tongue contour of two frames were tracked based on thearticulatory gesture using GetContours.

• Perception: A significant portion of utterances with consonantweakening is still perceived as voiced plosives (e.g.①-1), while otherinstances resemble glides or fricatives.
• Utterances exhibiting glide-like perception
retain vowel-like waveforms in the
acoustic closure interval (e.g.①-2 ),suggesting potential incompleteness inarticulatory closure formation.
However, only marginal differences were①-2
observed in tongue position (Figure 1).

posterior

References:[1] K, Maekawa. 2018. Weakening of Stop
Articulation in Japanese Voiced Plosives. Journal of
the Phonetic Society of Japan. 2018 Jun, 22(1), 21-34.
[2] P. Boersma, D. Weenink, “Praat: Doingphonetics by computer. Version 6.1.42, retrieved 2021
from http://www.praat.org/,” 2021.
[3] Tiede, M. K. 2022. GetContours. GitHub
repository,
https://github.com/mktiede/GetContours.
[4] S. N. Wood, Generalized additive models: anintroduction with R. chapman and hall/CRC, 2006.
[5] Warner N, Tucker BV. 2011. Phonetic variabilityof stops and flaps in spontaneous and careful speech. J
Acoust Soc Am. 130(3), 1606-17.

anterior

posterioranterior

1st: the onset of consonant articulatory movements of /ada/2nd: the maximal constriction point of /ada/• Here, we will only discuss voiced plosives.

• The audio signal and ultrasound video were recorded
simultaneously and synchronized using AAA software.

intervals.
Table 2: List of tongue highest point height rankings by speaker and weakening pattern (excluding data
whose ultrasound images cannot be analyzed)
CJF01
CJF03
CJF05
CJF06
CJF07
CJM02
CJM03
Averagerank/ada/ /ada/ /aga/ /ada/ /aga/ /ada/ /aga/ /ada/ /aga/ /ada/ /aga/ /ada/ /aga/⓪With burst
1211111112
111
1.15①Voiced glide
2213ーー2323122
2.09②③Frication
1112111231
123
1.54
Weakening
pattern

Influence of Place of Articulation• Differences in the frequency of weakening patterns
observed in different places of articulation (Table 3).
• ⓪with burst: /d/ > /b/ > /g/, different from thetendency observed in English(Warner&Tucker,2011),
but confirmed the results in Maekawa (2018).
• Maekawa attributed this sequence in Japanese to thecomplexity of the phonemic contrast among the placeof articulation within the phonological system.
Alveolar → plosive /d/, affricate /z/, nasal /n/
Bilabial → plosive /b/, nasal /m/
Velar→ plosive /g/③With
haltedPlace of⓪With①Voiced ②Voiced
Accentvocal fold
Articulation
burst
glide
frication
vibration
and ASP
HL
35
43
57/b/LH
47
29
122ALL
82
72
179HL
62
12133/d/LH
75
771ALL137
19204HL
25
30
278/g/
LH
4322232ALL
6852
50
10Individual Variation• Repeated × 10 with 2 pitch accent patterns(High-Low &Low-High), randomized• Mid-sagittal images of the oral cavity were recorded with
an ultrasound system (MicrUS, EXT-1H) using a
microconvex probe (MC10-5R10S-3). Video frame rate
was 113fps.

• The height of the tongue
contours at the maximal
constriction point:
Figure 2: Tongue contours for CJF05/ada⓪>②③>① (e.g. CJF05/ada/). through GAM plots with 95% confidence

Figure 1: Tongue contours for CJF03/ada/, CJM02/aga/ and CJM03/aga/ throughGAM plots with 95% confidence intervals.

• Pronounced in a carrier phrase (/korewa ___ to iːmasu/‘this is called ___’).

• The audio signal was digitally recorded at 22,050 Hz, 16bit resolution, using a RODE-NT2-A microphone.

• Ultrasound images for different
weakening patterns wereplotted by GAM model andvisually compared.

Table 3: Number of weakening pattern utterances for each place of articulation and accent• Stimuli: Non-lexical "aCa" sequences
Consonants = "p/b, t/d, k/g“

Audio & Ultrasound Recording

Is Frication Higher than Glide?

Weakening Patterns

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

3aSC23• Some speakers exhibit consistently low rates of weakening across all
consonants, while others, excluding the low weakening rate of /d/,pronounce /b/ and /g/ with almost no burst.

Influence of Pitch Accent• Most speakers demonstrated distinct tongue movements with andwithout weakening (CJF06/aga/, Figure 4 top 3 pictures).

III. Figures were plotted overlaying utterances from each speaker • CJF03/aga/(bottom) exhibited not only a higher rate of weakening but
based on weakening patterns → to visualize the progression
also appeared to have minimal tongue movement. It is moreof tongue movements.
suggestive of unclear articulation rather than consonant weakening.

Weakening pattern proportion for each accent and place of articulation
90%
80%
70%
60%

IV. The predicted tongue contours at the maximal constriction
point from the repetitions were plotted by speaker for eachweakening pattern using a generalized additive model (GAM).
→ to clarify the correlation between consonant weakening inplosives and constriction created by the tongue.
V.

50%40%30%20%10%0%Instances with synchronization errors or images too unclear
for tracking were excluded from the analysis.

Conclusion• In Japanese, intervocalic voiced plosives undergo weakening not only in spontaneous,natural speech but also in careful speech recorded in a controlled lab environment.
• This weakening can be categorized into three patterns based on the degree of obstruction
and the persistence of vocal fold vibration: ① Voiced glide pattern, ② Voiced frication
pattern, and ③ Pattern with halted vocal fold vibration and weak aspiration.

Figure 4 : Tongue contours of tongue body gesture onset and max for CJF06/aga/ & CJF03/aga/.

/b//b//d//d//g//g/HL

LH

HL

LH

HL

LH

⓪With burst①Voiced glide②Voiced frication③With halted vocal fold vibration and ASP

Figure 3 :Weakening pattern proportion for each accent and place of articulation• LH patterns exhibited lower rates of weakening
compared to HL patterns, with a tendency for• The susceptibility to weakening is influenced not only by the strength
increased susceptibility to weakening when there wasof intonational boundaries but also by accent patterns.
a pitch fall.
• There were differences in the frequency of weakening patterns
depending on the place of articulation.
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• There is individual variation in the rate of weakening.