PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Active control and passive consequence of vowel devoicing inJapanese: Evidence of highspeed movies and PGG
Masako FUJIMOTO1; Seiya FUNATSU2; Ichiro FUJIMOTO3
1

Waseda University, Japan

2 Prefectural University of Hiroshima, Japan
3 Takushoku University, Japan

ABSTRACT
Vowel devoicing is a phenomenon that is found in many languages including Japanese, Korean and Montreal
French. The typical case of VD in Japanese is that high vowels /i/ and /u/ are surrounded by voicelessobstruents. However, the frequency of occurrence of VD differs depending on consonant types, accent,dialects, and so on. Previous physiological studies have shown that VD in Japanese involves both active
re-organization of the glottal opening pattern during /C̥VC̥/ and passive overlapping of the glottal opening
gesture for each voiceless consonant. The former is regarded as phonological and the latter, phonetic. This
paper demonstrates the rich variety of the glottal opening pattern during VD using a high-speed digital movieof the laryngeal area and Photoglottography (PGG). This report covers the difference between typical andatypical devoicing environments and that between Tokyo and Osaka dialects, as well as the pattern of VD
before geminates and consecutive devoicing.
Keywords: Vowel devoicing, high-speed digital movie, Photoglottography (PGG), before geminates,
consecutive devoicing

1. INTRODUCTION
Vowel devoicing (VD) is a phenomenon that is found in many languages including Japanese,
Korean and Montreal French. The general condition of VD in Japanese is that high vowels /i/ and /u/are surrounded by voiceless obstruents. However, the frequency of occurrence of VD differs
depending on consonant types, accent, dialects, and so on. VD is less frequent 1) when surrounding
consonants are both fricatives such as /sis/ and /huh/ compared to /sik/ and /hut/; 2) when target vowels
are accented as /ki’t/ compared to /kit/ (/’/ denotes accent nucleus); 3) in Kyoto or Osaka dialects
compared to Tokyo (standard) Japanese (1-3).
Previous physiological studies have shown that VD in Japanese involves both active re-organization of
the glottal opening pattern during /C̥VC̥/ (4,5) and passive overlapping of the glottal opening gesture for eachvoiceless consonant (6). The former is often regarded as phonological and the latter, phonetic. This paper
demonstrates a rich variety of the glottal opening pattern during VD using a high-speed digital movie oflarynx and Photoglottography (PGG). This report covers the difference between stop and fricative
consonants and that between Tokyo and Osaka dialects, as well as the pattern of consecutive devoicing, VD
before geminate consonants.
In many of the studies of VD, speech waveforms are used to speculate the states of the glottal
settings, open or closed, as well as the characteristics of vocal fold vibration. However, seemingly
similar acoustic outcomes can often be produced by different mechanisms in terms of active control at
the higher level of speech production as well as passive consequences of glottal gesture overlap at thelower level of speech production (6). This paper gives evidence about the correspondence between
acoustic signals and actual states of the glottis, with special reference to the vocal fold’s vibration
during vowels.

1m.fujimoto5@kurenai.waseda.jp
funatsu@pu-hiroshima.ac.jp
3ifujimot@ms.takushoku-u.ac.jp
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2. Method
2.1 Speakers
Four speakers of Japanese (three males, one female) between 32 to 53 (av. 39) years old served as
subjects. In the present paper, they are referred to TM, TF, OM and OF, where M and F stand for maleand female, with T and O, for Tokyo (Standard Japanese) and Osaka dialect, respectively.
2.2 Test Words
Test words were selected to fit the necessity of several studies. The test word sets and break down
lists for recordings differ among subjects. Ten words were selected for the analysis of the present study,
as shown in Table 1. Two tokens were recorded for each word. All words are non-words: either
three-mora without geminates or four-mora with geminates. Vowels /i/ and /e/ were used in this study,
since the epiglottis does not tilt backwards for their production, which disturbs the glottal view.
Table 1 – Test words in the present study. ‘St,’ ‘Fr,’ ‘C̥,’ ‘QC̥,’ and ‘Vnh’ stand for stops, fricatives, voicelessconsonants, voiceless geminate consonants and non-high vowels, respectively.
devoicing condition

consonantal condition

words

Typical

St-St, Af-Af, Af-St/ekiki/ [ekiki], /etiti/ [eʨiʨi], /etite/ [eʨite]

AtypicalFr-Fr/esisi/ [eɕiɕi], /esise/ [eɕise]

Before geminate

C-QC/ekkiki/ [ekkiki], /ettiti/ [etʨiʨi], /essisi/ [eɕɕiɕi]

Consecutive devoicing

St-St-St/tititi/ [ʨiʨiʨi]

Non-high vowel

C-Vnh-C/ekeke/ [ekeke]

2.3 Data Recordings
Simultaneously with the speech sound and Photoglottogram (PGG), laryngeal images weredigitally recorded using a fiberscope though a nostril at the rate of 4500 frames/sec. Speakers read fiveto ten words in a list in isolation during a recording session at their comfortable speech tempo and(pitch) accent pattern. Duration of each session was 6 seconds for TM, and 14 seconds for TF, OF andOM, depending on the recording equipment used for the experiments. Figure 1 schematically shows
the setting of the recordings.

Figure 1: Block diagram of the experimental setting.
2.4 Data Analyses
Glottal images were analyzed using Adobe Photoshop 10. Audio and PGG signals were analyzed
using the software SONY PCscan Ⅱ and Praat (ver 6.0.29). Vowels were judged as devoiced when theaudio signal did not show one or more waves which typically correspond to vocal fold vibration.
Figure 2 shows examples of glottal images on the left, and audio and PGG signals on the right, of/ekiki/ uttered by TM.

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Figure 2 – Left panel shows the glottal image during /etiti / by TM. The vertical line on the acoustic signal
denotes the timing of glottal images. The right panel shows the acoustic and PGG signal of the same token.

3. RESULTS
3.1 Devoicing Rate
Table 2 shows the devoicing rate of the target vowel /i/ in the test words. The result showed that 1)
vowel devoicing occurred more frequently for the Tokyo speakers than for the Osaka speakers; 2)
within the Tokyo speakers, devoicing was consistent in the ‘Typical’ environment but not in the‘Atypical’ and or ‘Before geminates’ environments; 3) one token by TM showed ‘Consecutive’devoicing; 4) non-high vowels did not devoice for any of the speakers. Three of the speakers read thewords with the unaccented LHHH pattern; OF read four mora words with an unaccented pattern andthree mora words with an accented HLL pattern.
Table 2 – Devoicing rate according to test words and speakers. Numerator of fraction denotes the number ofdevoicings out of the total number, indicated in the denominator.
devoicing condition

test words

TMTF

OM

OF/ekiki/

2/2

2/2

0/2

0/2

/etiti/

2/2

2/2

0/2

0/2

/etite/

2/2

2/2

2/2

2/2

/esisi/

1/2

0/2

0/2

0/2

/esise/2/2

2/2

0/20/2/ekkiki/

2/2

1/2

0/2

0/2/ettiti/

2/2

0/2

0/2

0/2/essisi/

0/2

0/2

0/2

0/2

Consecutive devoicing/tititi/

1/2

0/2

0/2

0/2

Non-high vowel/ekeke/

0/2

0/2

0/2

0/2

TypicalAtypicalBefore geminates

3.2

Glottal Images

3.2.1 Typical Devoicing Environments
Figure 3 shows a series of the glottal images with the audio signal of /ekiki/ by TF. The degree ofglottal opening increases during the period of devoiced CVC, reaching a maximum opening after therelease of /k/ near the devoiced vowel. It then decreases towards /k/ in the third mora. The degree ofglottal opening during /k/ in the second mora is much larger than that in the third mora. This suggeststhat the glottal opening during the devoiced vowel is positively controlled, probably not due to theoverlap of two glottal openings for each consonant.
Figure 4 shows a series of glottal images with the audio signal of /etiti/ by TM. Again, the degree ofglottal opening increases during the period of devoiced CVC, reaching a maximum opening after therelease of /t/ near the devoiced vowel and then decreasing towards the /t/ in the second mora. The
degree of glottal opening during /t/ in the first mora is much larger than that following the devoiced
CVC. This suggests that the glottal opening during the devoiced vowel is positively controlled ; it is
not due to the overlap of two glottal openings for each consonant.

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Figure 3 – Glottal images during /ekiki/ with devoiced /i/ by TF. The vertical line on the acoustic wave
denotes the timing of each glottal image.

Figure 4 – Glottal images during /etiti/ with devoiced /i/ by TM.
Figure 5 shows the audio and PGG signal of /ekiki/ by TF and /etiti/ by TM corresponding to Fig 3and 4, respectively. The pattern of the glottal opening is a smooth monomodal shape during thevoiceless CVC with its peak at around the voiceless vowel for both tokens. This confirms the analysisof the glottal images mentioned above.

Figure 5 – Audio and PGG signals of /ekiki/ by TF (left) and /etiti/ buy TM (right). The duration of each panel
is 700 ms.
For Osaka speakers, VD occurred only in /etite/ but not in the other words. For /etite/, two tokens
were devoiced for both speakers. Figure 6 shows the glottal images with the audio signal of /etite/ byOM. The glottal opening is large during the devoiced /tit/, which is similar to the Tokyo speakers, but
the maximum opening comes earlier at the release of /t/. Figure 7 shows the glottal images with theaudio signal of /etiti/ by the same speaker. For this test word, /i/ in was not devoiced in both tokens.
The degree of glottal openings during the /t/s in /etiti/ are much smaller than those of the devoiced /tit/in /etite/ in Fig 6.

Figure 6 – Glottal images during /etite/ with devoiced /i/ by OM.

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Figure 7 – Glottal images during /etiti/ by OM. /i/ is not devoiced.
Figure 8 compares the audio and PGG signals of /etite/ and /etiti/ by OM. The PGG signal during/tit/ is clearly different depending on whether the vowel is voiced or devoiced. The degree of glottal
opening of /tit/ in /etite/ is large while that of the two /t/s in /etiti/ are small. The pattern of voiceless
CVC differs from that by Tokyo speakers. Recall that the maximum opening of voiceless CVC by
Tokyo speakers is around the voiceless vowel. In contrast, the maximum opening of /etite/ occurs at
the beginning of the frication noise of the first /t/. It then decreases to its lowest degree at the end of thedevoiced /t/ and keeps the low level of opening during the closure of the second /t/. This pattern can beregarded as a merged shape of one big opening for /ti/ and a small opening for /t/.

Figure 8 – PGG and audio signal of /etite/ and /etiti/ by OM. The duration of the panel is 700 ms.
Figure 9 shows the glottal images of two tokens of /etite/ and /etiti/ by OF. Although /i/ in /etite/
was devoiced in both tokens, the degree of glottal opening of /tit/ significantly differs between the two,
one small (leftmost panel) and one large (second panel). The smaller opening is similar to the two /t/sin /etiti/ shown in the right two panels. This suggests that the glottal opening is re-organized in thesecond token to produce a voiceless CVC with a large opening, but it is as small as a single /t/ in thefirst token. Figure 10 shows the audio and PGG signals of the same three tokens of Fig 9. The PGG
pattern corresponds to this analysis.

Figure 9 – Glottal images of /etite/ and /etiti/ by OM. Left two panels are images near the timing of thedevoiced /i/ from two different /etite/ tokens. The right two are at the first and second /t/s in a /etiti/ withvoiced /i/.

Figure 10 – PGG and audio signal of /etite/ and /etiti/ by OF. Left two panels are /etite/ with devoiced /i/ andright panel, /etiti/ with voiced /i/. The duration of each panel is 700 ms.

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3.2.2 Atypical Devoicing Environments
For the words /esisi/ and /esise/, both with atypical devoicing environments, VD occurred for twotokens in /esise/ and one token in /esisi/ by TM, two tokens in /esise/ by TF, but none for OM and OF.
The results agree with the previous finding that devoicing in atypical devoicing environments isnon-systematic and less frequent. Figure 11 shows the glottal images during /esise/ by TF. The glottis
opens widely during the devoiced CVC and maximally in the middle at around the devoiced vowel.
Figure 12 shows the audio and PGG signals of the same token. The PGG pattern differs from that in a
typical consonantal environment shown in Fig 5. While the PGG signal of /ekiki/ in Fig 5 shows a
simple mono-modal pattern, that of /esise/ in Fig 12 resembles a plateau-like shape. This pattern canbe regarded as a merged shape of two big openings for the first and second /s/s, which results in thedevoicing of /i/ between them.

Figure 11 – Glottal images during /esisi/ by TF. The vertical line on the acoustic signal denotes the timing ofglottal images.

Figure 12 – PGG and audio signal of /esise/ by TF. The duration of the panel is 700 ms.
3.2.3 Before geminates
Figure 13 shows glottal images during /ekkiki/ by TM and figure 14, audio and PGG signals of thesame token. The glottis opens widely during the devoiced CVCC and maximally at the latter half near
the frication of the devoiced vowel. Thus, the glottal opening pattern of devoiced CVCC differs fromthat of voiceless CVC in terms of the later timing of the peak opening and its right-skewed shape.

Figure 13 –Glottal images during /ettiti/ by TM. The vertical line on the acoustic wave denotes the timingof glottal images.

Figure 14 – PGG and audio signal of /ettiti/ by TM. The duration of the panel is 700 ms.

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3.2.4 Consecutive Devoicing
As for the test words /kikiki/ and /tititi/, consecutive devoicing occurred in only one token /tititi/ byTM. Figure 15 shows the glottal images of the word where the first and second /i/s were devoiced andfigure 16, audio and PGG signals of the same token. The glottis opens throughout the voiceless
CVCVC and most widely during the first voiceless CV (the third panel in Fi g. 15). In this respect, interms of the timing of the peak opening, the glottal opening pattern of a devoiced CVCVC differs fromthat of a voiceless CVC in a typical devoicing environment. Namely, while peak opening comes in themiddle around the devoiced vowel in CVC, it occurs in the first half in a voiceless CVCVC. Due to thisremarkably large opening, the light passed though the glottis exceeded the limit of the experimental
setting and the PGG signal was saturated at the first half of the devoiced CVCVC. Nonetheless, it isclear that the PGG signal skewed left. It is also noticeable that the shape of the latter half of the PGG
signal shows a bi-modal pattern, i.e. a small plateau follows after a rapid decrease at the end of theCVCV.

Figure 15 – Glottal images during /tititi/ by TM where first and second /i/s were devoiced. The vertical lineon the acoustic wave denotes the timing of glottal images.

Figure 16 – PGG and audio signal of /tititi/ by TM. The duration of the panel is 700 ms.
3.2.5 Non-high Vowel
The non-high vowel /e/ did not devoice at all regardless of the test word or the speaker. Figure 16
shows the glottal view during /ekeke/ by OM and Figure 17, audio and PGG signals of /ekeke/ by OF.
As is clear from the images, glottal opening of /k/ is as small as or even smaller than that of the opening
phase of a cycle of the vowel /e/, which is clearly indicated in the PGG signal. This means that theglottal opening of the word medial /k/ is small.

Figure 16 – Glottal images during /ekeke/ by TM vowels /e/s were not devoiced. Vertical line on the acoustic
wave denotes the timing of glottal images.

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Figure 17 – PGG and audio signal of /ekeke/ by TM. The duration of the panel is 700 ms.

4. DISCUSSION
The present results confirm the dialectal differences as well as the difference s in consonantalenvironments with regard to VD rate. As expected, VD was less frequent in the Osaka speakers than
the Tokyo speakers. Also, VD rate is more frequent in typical consonantal environments. Even though
VD is very infrequent for the Osaka speakers, it occurred only in typical consonantal environments.
For the Tokyo speakers, VD occurred in typical devoicing environment s regardless of test words, but
not systematically in atypical environments before geminates and consecutive conditions. VD in
non-high vowels did not occur at all.
In typical devoicing environments, glottal opening during devoiced CVC by the Tokyo speakers
was mono-modal and large without exception. Peak glottal opening during devoiced CVCC was alsomono-modal and large, although the peak came later than CVC. These results are consistent withprevious studies. Such VDs are regarded to be controlled electromyographically (4). In contrast,
glottal opening during a devoiced CVC in atypical environments showed a plateau pattern, and during
devoiced CVCVCV, a bimodal one. These devoicings by Tokyo speakers may be passively derived.
For an Osaka speaker, notably small glottal opening corresponded to devoiced CVC in one of thetokens. This agrees with the previous result using another Osaka speaker (5). Such VD may not be
controlled electromyographically and, thus, occurred passively.
Although the data are limited, the present results demonstrate that the occurrence of VD in Japanese
is not a simple phonological event with binary choice but embraces a variety of gradual states which
depend on phonetic realization in each token.

5. FINAL REMARKS
By using high-speed movies and PGG, this study shows the rich varieties of glottal opening
patterns during different segmental conditions. The results shed light on some of the articulatory
mechanisms and uncover differences in devoicing patterns, found from time to time in Japanese.
Further study is necessary to clarify the whole mechanism of vowel devoicing.

ACKNOWLEDGEMENTS
This study was partly supported by JSPS Kakenhi 17K02707 and 15K02524.

REFERENCES
1. Sakuma K. Nihon Onseigaku [Japanese Phonetics],” Tokyo: Kyobunsha, 1930.
2. Kawakami S. Nihongo Onsei Gaisetu [Introduction of Japanese Phonetics] Tokyo:Ohfu, 1994.
3. Fujimoto M. Vowel devoicing, In Handbook of Japanese Phonetics and Phonology, Berlin: De Gruyter.
p. 167-214, 2014.
4. Yoshioka, H. Löfqvist, A. and Hirose, H., Laryngeal adjustments in Japanese voiceless soundproduction, J. of Phonetics 10, p. 1-10, 1982.
5. Fujimoto M., Murano E., Niimi S. and Kiritani.S. “Difference in glottal opening pattern between Tokyo
and Osaka dialect speakers: Factors contributing to vowel devoicing,” Folia Phoniatrica et Logopaedica,
54-3, p. 133-143, 2002.
6. Fujimoto M.㸪Glottal opening pattern in devoiced tokens by an Osaka dialect speaker, J. of Phonetic
Society of Japan, 9(1), p. 50-59, 2005.

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