VOT Merger and F0 Maximization between the

Lax and Aspirated Stop in Sound Change*

* This work was supported by the National Research Foundation of Korean Grant funded by the Korean Government (NRF-2012-2012S1A5A2A01018746). I would like to thank three anonymous reviewers for their thoughtful comments. All remaining errors are mine.

Mi-Ryoung Kim

(Korea Soongsil Cyber University)

∣ Mi-Ryoung Kim

VOT Merger and F0 Maximization between the Lax and Aspirated Stop in Sound Change ∣

Kim, Mi-Ryoung. (2013). VOT Merger and F0 Maximization between the Lax and Aspirated Stop in Sound Change. The Linguistic Association of Korea Journal, 21(2), 1-20. Recent studies show that Korea stops—the lax and aspirated stop—are undergoing a sound change. This study examines two acoustic parameters—voice onset time (VOT) and fundamental frequency (f0)—to see how their values are diachronically changing (i.e., sound change) and whether there are individual differences in sound change. Acoustic data on VOT and f0 are compared with the results of Han & Weitzman’s (1970). Results show that VOT values between the lax and aspirated stop are merged whereas f0 differences are maximized to contrast the aspirated and lax onsets. This can be characterized by the loss of a consonantal opposition in terms of VOT and the maximization of a vocalic portion in terms of f0. In addition, there are individual differences in sound change. The results suggest that Korean is still undergoing a sound change and the process of a sound change is analogous to tonogenesis. Further discussion is necessary on how tonogenesis can be applied for the explanation of a sound change in Korean.

Key Words: VOT merger, f0 maximization, the sound change of Korean stops, tonogenesis

1. Introduction

Korean has three stops, described as aspirated /ph, th, kh/, tense or fortis /p*, t*, k*/, and lax or lenis /p, t, k/. The classic examples are shown in (1) (Note that the tense series is often marked as /tt/ or /t’/ in other studies).

(1) /thal/	‘mask’

/tal/	‘moon’

/t*al/	‘daughter’

Since C.-W. Kim (1965), all three Korean stops have been described as voiceless. This view has been widely accepted among many linguists (see M.-R. Kim, 2000; Kim & Duanmu, 2004 for a different proposal). Kim & Duanmu (2004, p. 77) describes, “While languages with two kinds of voiceless stops are common, such as Hindi, Thai, and Chinese, Korean is the only language that reportedly has three.” This makes Korean stops unique in the world’s languages. Arguing against the traditional view, an alternative view was first introduced by M.-R. Kim (2000). She proposes that Korean stops can be analyzed as regular stops that contain a voiced and voiceless distinction in the underlying representation. In addition many issues of Korean stops are controversial and remain unsolved. Since the issue is not the main concern of the present study, the detailed review is skipped (see Kim & Duanmu, 2004; M.-R. Kim, 2012a and 2012b). Because of controversial issues, numerous investigations have thus far explored the precise phonetic characteristics of these stops. Among them, studies of two major acoustic parameters, voice onset time (VOT) and fundamental frequency (f0), are considered as important cues to contrast Korean stops and are discussed below.

Since Lisker & Abramson (1964), VOT has become an important acoustic parameter to distinguish stops in the languages of the world (Ladefoged & Maddieson, 1996). It has been found to be effective as a means of separating phonemic categories when some languages are utilized in conjunction with voicing to yield two, three or four categories (Klatt, 1975). It has been widely accepted as a sufficient cue to distinguish voiced from voiceless stops in most of the world’s languages. Since Korean stops are all voiceless, however, VOT alone is not sufficient enough to contrast them because of its overlapped values as discussed below.

Early studies report that, on average, VOTs are shortest for the tense stop, intermediate for the lax stop, and longest for the aspirated stop, with some overlap between the lax and tense stop (Lisker & Abramson, 1964; C.-W. Kim, 1965; Han & Weitzman, 1970; M.-R. C. Kim, 1994). The example is excerpted from Han & Weitzman’s (1970) as shown in Figure 1.

FIGURE 1. Mean VOT values according to the aspirated, lax, and tense stop. The pooled and individual data are illustrated in Figure 1(a) and Figure 1(b), respectively. The pooled data are averaged across three Seoul speakers (1 male and 2 females).

Han & Weitzman (1970) report that mean VOT for the tense stop is shortest (Mtense 11 in the range of 9 to 13 ms). Mean VOT for the lax stop is much shorter (Mlax 30 in the range of 10 to 65 ms) than for the aspirated stop (Masp 107 in the range of 66 to 148). They show that there is some overlap of the VOT ranges between lax and tense stop whereas there is little VOT overlap between the aspirated and lax stop (Lisker & Abramson, 1964; C.-W. Kim, 1965; Han & Weitzman, 1970; M.-R. C. Kim, 1994). With respect to a three-way VOT category, the pooled data in Figure 1(a) hold well for the individual data in Figure 1(b). Although there were variations in VOT duration as well as some overlap between lax and tense stops, 3-way VOT distinction is captured well by all three individual speakers. With respect to VOT duration in Figure 1(b), mean VOTs for all three stops are shortest for speaker 3, intermediate for speaker 2, and longest for speaker 1. Despite individual differences in VOT duration, it is worth noting that there is no merger between aspirated and lax stops in Han & Weitzman’s (1970) data. In earlier studies, VOT is considered to be an important cue to contrast the three phonation types in initial position in Korean (Lisker & Abramson, 1964; C.-W. Kim, 1965; Han & Weitzman, 1970; M.-R. C. Kim, 1994).

Early findings on VOT can be comparable to those recent findings. Unlike early findings, recent studies show that VOT values between the lax and aspirated stop are remarkably overlapped (Choi, 2002; Silva, 2006; M.-R. Kim, 2008, 2011, 2012a, 2012b; Wright, 2008; Kang & Guion, 2008; Oh, 2011). Owing to the merger, a 3-way VOT distinction is merged into a 2-way distinction, suggesting that the two stops are undergoing a sound change  (Silva, 2006; M.-R. Kim, 2008). Noticeable interspeaker variations on VOT have been reported in terms of socio-indexical aspects (i.e., age, dialect, gender, and L2 proficiency) as well as even within each factor (Choi, 2002; Kenstowicz & Park, 2006; Silva, 2006, M.-R. Kim, 2008; Wright, 2008; Kang & Guion, 2008; cf, Cho et al, 2002). Silva (2006) reports that the merger was found among younger speakers (see also Wright, 2008; Kang & Guion, 2008). However, M.-R. Kim (2008) found remarkable interspeaker variation on the VOT merger and duration even in the same generation, as can be seen in Figure 2.

FIGURE 2. The individual data: Mean VOT values (ms) and range (within 1 standard deviation) produced by female Seoul speakers according to aspirated, lax, and tense targets in initial position. Data are presented according to age, 20’s, 40’s, and 50’s (cited from M.-R. Kim, 2008, p. 195).

Similarly, individual differences in the VOT merger are noticeable for other factors such as dialect, gender, and L2 proficiency. With respect to the effect of dialect on VOT, Choi (2002, p. 17) reported that, out of the two Seoul male speakers, only one showed a substantial VOT overlap between lax and aspirated stops. Cho et al. (2002) did not find a VOT merger from Seoul speakers. With respect to the effect of gender on VOT, Oh (2011) reported that female speakers showed more frequent merger than male speakers. M.-R. Kim (2011) reported the effect of L2 proficiency in the VOT merger in that the merger was more prominent among advanced L2 speakers than among L2 beginners, suggesting that the actuation problem in sound change is related to language contact. However, M.-R. Kim (2011, 2013) found noticeable interspeaker variations even in the same L2 proficiency group. Because of interspeaker variation even within each factor, it is still not clear what factor initiates and propagates the VOT merger in Seoul Korean.

Instead of VOT, f0 is considered to be more important cue to contrast the aspirated and lax stop (M.-R. Kim, 2000). As attested by Kim et al. (2002), f0 differences triggered by initial onsets are crucial to contrast the words /thal/ ‘mask’ and /tal/ ‘moon’, focusing on its perceptual role as follows:

While H1-H2 differences distinguish Korean tense stops from aspirated and lax stops, and differences in VOT values most clearly differentiate aspirated from tense and lax stops, differences in f0 best differentiate Korean lax stops from aspirated and tense stops Kim et al. (2002, pp. 78).

In early findings, on average, f0 is lowest for vowels following lax stops, higher following tense stops, and highest for following aspirated, although the f0 ranges reported for the tense and aspirated categories substantially overlap. This can be seen from Han & Weitzman’s (1970) result in Figure 3. In Figure 3, for lax and aspirated stops, mean f0 differences at vowel onset were 41 Hz (in the range) for a male speaker and 43 Hz for a female speaker, respectively. For aspirated and tense stops, mean f0 differences at vowel onset were 41 Hz for a male speaker and 43 Hz for a female speaker, respectively. For both speakers, there was some f0 overlap between aspirated and tense onsets.

Han & Weitzman’s (1970) results on f0 at vowel onset can be comparable to M.-R. Kim’s (2000) to see how f0 differences among the three phonation types are diachronically shifted. Figure 4 gives mean f0 contours according to the word initial consonant in Korean monosyllables, data from M.-R. Kim (2000).

FIGURE 3. Individual mean f0 contours of a male and female speaker according to aspirated, tense, and lax stops based on measures taken at vowel onset in monosyllables (cited from Han & Weitzman’s f0 values of individual speakers).

FIGURE 4. Overall mean f0 contour according to initial consonant based on measures taken at rime onset, midpoint, and offset of monosyllables. Data are averaged across three Jeonnam speakers (2 males and 1 female) and five Seoul speakers (3 males and 2 females). The standard error represents one standard deviation (cited from M.-R. Kim, p. 68).

Compared with Han & Weitzman’s f0 results, mean f0 differences between aspirated and lax stops were slightly greater n M.-R. Kim’s (2000) results (Masp-lax = 43 Hz vs. Masp-lax = 50 Hz). M.-R. Kim (2000) reported that, “at rime onset, there is a 20 Hz f0 gap between aspirated and tense consonants (with higher f0 after aspirated consonants than after tense counterparts), but the gap is much narrower (about 8 Hz) at midpoint and offset.” She suggested that the f0 differences due to phonation type are sufficiently extensive such that they have been analyzed as phonologized tones in Korean: L tone conditioned by initial lax consonants and H tone conditioned by initial aspirated and tense consonants (Gim, 1969; Jun, 1993; Kim & Duanmu, 1998; Kim et al. 2002). The onset-tone correlation in L1 Korean was also found in L2 English: L tone correlated with voiced onsets and H tone correlated with voiceless counterparts (Kim & Park, 2001; M.-R. Kim, 2012c). Jun (1993) suggests that those tones are properties of Korean intonational phonology. M.-R. Kim (2000, 2012a, 2012b) suggests that sound change in Korean can be analyzed as standard tonogenesis (i.e., voiced-L and voiceless-H) as in other Asian languages. Further discussion is necessary on some phonological speculations of tonogenesis.

With respect to sound change in Seoul Korean, previous studies on sound change have focused on group effects for socio-indexical factors such as age, gender, dialect, and L2 proficiency. Less attention has been paid to the role of individual speakers’ actuation and propagation problem in sound change. The current study is designed to investigate individual effects of phonation types on VOT and f0 contours, focusing on individual differences in sound change in Seoul Korean. In order to see individual differences, socio-indexical factors such as age, gender, dialect, and L2 proficiency are controlled in the present study. In addition the findings of the current study are compared to the results of Han & Weitzman’s (1970) to see how the behaviors of VOT and f0 are diachronically shifted.

2. Methods

2.1 Participants

For the direct comparison of Han & Weitman’s (1970) study, the same number of participants (i.e., three) employed as participants. The aforementioned socio-indexical factors such as age, gender, dialect, and L2 proficiency that might affect sound change were all controlled to see whether there were still individual differences in sound change in Seoul Korean. All speakers were females in their twenties. The mean age was 28 years, 6 months and the individuals ranged from 25 years, 4 months to 29 years, 3 months. They were born and grew up in Seoul and spoke a standard Seoul dialect. With respect to L2 proficiency, they were purely L2 beginners because they had no experiences in living in an English speaking country more than 1 month. Although they had learned English at schools since their puberty, they were hardly able to communicate with a native speaker of English. In a broad definition, they can belong to Korean monolinguals.

“L2” is generally used as a cover term to refer to ESL (English as a Second Language) or EFL (English as a Foreign Language).

2.2 Speech materials and procedure

Eighteen words in Korean were constructed with a balanced list of phonation types (lax, aspirated, and tense stops), vowel context (/a/), and syllable types (CVC for monosyllabic words and CVCV for disyllabic words). All words were real, as presented Table 1.

TABLE 1. Speech stimuli

	Labial	Alveolar	Velar
Aspirated	/phaŋ/ ‘bang’ /phada/ ‘dig out’	/thal/ ‘mask’ /thada/ ‘to ride’	/khaŋ/ ‘proper name’ /khadɨ/ ‘card’
Lax	/paŋ/ ‘room’ /pada/ ‘sea’	/tal/ ‘moon’ /tado/ ‘tea ceremony’	/kaŋ/ ‘river’ /kada/ ‘to go’,
tense	/p*aŋ/ ‘bread’ /p*ada/ ‘to grind’	/t*al/ ‘daughter’ /t*ada/ ‘to pick’	/k*aŋ/ ‘percussion cap’ /k*ada/ ‘to peel’

In order to record the target words in a constant prosodic environment, each word was presented in a carrier sentence. The carrier sentence for the English data was “____ is the word.” The carrier sentence for the Korean data was “[______ has□jo]” (“Say ______”). For the target words, they were located in utterance-initial position. In utterance-initial position, the target words were expected to be fully stressed and emphasized. Overall, a total of 216 tokens (18 words x 4 repetitions x and 3 Korean speakers) were obtained for analysis.

Recordings were made in a sound-attenuated booth at a university in Korea using a Shure (model SM 10A) head-mounted microphone and a Marantz digital recorder (PMD 670) at a sampling rate of 44,100Hz. All recorded utterances were analyzed using Praat 5.3.32, a speech analysis program (Boersma & Weenink, 2012).

VOT was measured from the release burst to the onset of periodicity in the waveform (Lisker & Abramson, 1964). The onset of the vowel in the waveform was determined by the onset of the first full glottal pulse of the vowel as well as the pitch of the spectrogram. The onset of the voicing energy in the second formant shown in a time-locked spectrogram was used to help determine voicing onset in conjunction with the waveform. In order to capture the f0 contour of the syllable, f0 was measured at a 20 ms interval from the onset of voicing to 100 ms into the vowel. The onset of voicing (=vowel onset) was defined as the first and periodic pulse of a vocalic waveform that show features typical of a vowel.

Acoustic measurements were statistically tested using repeated measures analysis of variance (ANOVA) in the context of a mixed linear model (SAS Institute, 1996). Our main goal was to examine whether there is the effect of the phonation type on VOT and the f0s of its following vowel and whether VOT and f0 differences between speakers and the phonation type (i.e., aspirated, lax, and tense) were significant. Repeated measures ANOVA includes both “between” subjects effects and “within” subject effects (i.e., phonation type). Their main and interaction effects were statistically analyzed. Post hoc tests were run to answer the following questions: (i) whether any differences in pairs between subjects were significant and (ii) whether any differences in pairs between phonation types were significant. For statistical analysis, the VOT and f0 differences according to the three phonation types were focused because of most central interest in the present paper.

3. Results and Discussion

3.1 VOT merger and individual differences

Results of repeated measures ANOVAs showed that there was a main effect of Phonation type (F(2, 198) = 235.15, p < .0001) on VOT in that VOT was short for the tense stop (Mtense = 16 ms (range 2~30 ms) and long for the lax and aspirated stop (Masp = 71 ms (range 25~111 ms); Mlax = 68 ms (range 31~109 ms)). According to Lisker & Abramson’s terms about VOT distinction, both lax and aspirated stops were realized with long-lag voicing whereas tense stops were realized with short-lag voicing. Corresponding to previous findings (Lisker & Abramson, 1964; Han & Weitzman, 1970; M.-R. Cho Kim, 1994), tense stops were well-distinguished from either aspirated or lax stops. However, aspirated stops were not distinguished from lax stops in terms of VOT. Although post hoc pairwise comparisons showed that differences in any pairs were statistically significant (p < .0001), overall mean VOT values and ranges between the aspirated and lax stop were heavily overlapped as shown in Fig. 5(a) in the pooled data. For the pooled data, the VOT merger between the two stops in Fig. 5 (a) corresponds to previous findings (Silva, 2006; M.-R. Kim, 2008). However, the pooled data do not hold for across all three individual speakers as shown in Fig. 5(b).

FIGURE 5. The pooled (a) and individual (b) data: mean VOT values of three phonation types in the initial position of Korean words produced by three Korean female Seoul speakers. Error bar indicates +1 standard deviation.

In Fig. 5, the pooled data show that, unlike tense stops, mean VOTs between aspirated and lax stops are completely merged, showing a two-way VOT category, short-lag VOT for the tense stop and long-lag VOT for the aspirated and lax stop. The merger in the pooled data was analogous to the earlier findings of Silva (2006) and M.-R. Kim (2008, 2013). Despite the fact that speakers were controlled in terms of age, dialect, and gender, there were still individual differences in the VOT merger and duration. Speaker 1 and 3 showed a complete merger whereas speaker 2 showed a partial merger. Second, there were individual differences in duration: for the aspirated stop, VOT is shortest for speaker 3, intermediate for speaker 2, and longest for speaker 1. For the lax stop, VOT is longer for speaker 1 than for speaker 2 and 3. In addition, there are differences in the VOT pattern for the lax and aspirated stop. Mean VOT differences for the aspirated stop were relatively longer than the lax stop for speaker 2 (asp > lax), almost similar for speaker 1 (asp = lax), and shorter for speaker 3 (asp < lax). For the both stops, overall mean VOT duration is relatively shorter for speaker 3 than the other two speakers. Individual differences on VOT are summarized in Table 2.

TABLE 2. Individual differences in VOT merger, duration, and pattern

VOT pattern	Mean (range)	Merger	Duration	Participant
Asp > lax	Masp = 68 ms (28~93 ms) Mlax = 56 ms (31~92 ms)	partial	intermediate	S2
Asp = lax	Masp = 82 ms (53~111 ms Mlax = 83 ms (63~109 ms)	complete	long	S1
Asp < lax	Masp = 47 ms (25~63 ms) Mlax = 55 ms (35~85 ms)	partial	short	S3

Very interestingly, as seen in Table 2, three individual speakers each show different VOT pattern, duration, and merger type. This suggests that there may be huge interspeaker variation among Seoul Korean speakers.

As discussed in Silva (2006), VOT values have been diachronically shifted in terms of the merger, duration, and pattern. The findings in the present study can be comparable to Han & Weitzman’s findings. For direct comparison between the two studies, their pooled and individual data from Fig. 1 and 5 are collapsed and represented in Fig. 6.

In Fig. 6, the present findings are different from Han & Weitzman’s in three aspects. First, there were individual differences in the VOT merger. In Han & Weitzman’s data, there was no VOT merger for both the pooled and individual data. The three-way contrast is well distinguished in terms of VOT: the mean VOT is shortest for the tense stop, intermediate for the lax stop, and longest for the aspirated stop. The pooled results hold well for across the three speakers without interspeaker variation. However, the merger is robust in the present results. In addition there are individual differences in the merger. As a result, there was a 2-VOT category in the current study but a 3-VOT category in Han & Weitzman. Second, there was difference and interspeaker variation in the VOT duration. As seen in Fig. 6, compared with Han & Weitzman’s, VOT values for the aspirated stop are much shorter whereas lax stops are much longer. The current results in Fig. 6(b) suggest that the sound change between the two stops can be characterized by a VOT shortening for the aspirated stop but a VOT lengthening for the lax stop. Third, interspeaker variations in the current results are greater than those in Han & Weitzman in terms of the VOT merger and duration.

FIGURE 6. Mean VOT values according to the three phonation types in the initial position of Korean words. The left panels are (a) the pooled and (b) individual results of Han & Weitzman (1970) and the right panels are those of the present study.

Individual differences in sound change in Seoul Korean suggest that VOT values between the lax and aspirated stop are still in the process of changing toward the merger. With respect to sound change, some speakers belong to innovators in sound change whereas other may not. An anonymous reviewer comments that sound change in a particular language is initiated by an individual speaker, propagated from one speaker to the speaker, and extended to a group in the language. Some speakers can be innovators that may actuate and propagate a sound change actively whereas other speakers may be conservative speakers that may be reluctant to change their pronunciation (Silva, 2006). If this is correct, we may expect that the sound change in Seoul Korean from some individual speakers may be extended into other group of speakers until it is complete. However, a question still remains unsolved: what factor initiates a sound change for some Seoul Korean speakers.

3.2. F0 maximization and individual differences

Results of repeated measures ANOVAs showed that there was a main effect of Phonation type (p < .0001) on f0 at all six measurement points in that f0 was highest for the tense and aspirated stop and lowest for the lax stop as shown in Fig. 7.

FIGURE 7. Overall mean f0 contour according to each phonation type based on measures taken at 20 ms intervals from the onset of the first regular vocal pulse till the 100 ms into the vowel of the target syllable, averaged across three female Seoul speakers.

The current results corresponded to the previous results of Jun (1993) and M.-R. Kim (2000) in two aspects as follows. First, with respect to the nature of the effect, i.e.., how phonation types are grouped, lax onsets are correlated with a L tone whereas tense/aspirated onsets are correlated with a H tone. As can be seen in Fig. 7, f0 contours following aspirated and tense stops are remarkably higher than those following lax counterparts. For the aspirated/tense and lax stop, mean f0 differences were significant throughout six measurement points (p < 0.0001). However, the tense and aspirated categories substantially overlapped at some measurement points, suggesting that there was an apparent f0 merger between the two stops. Post hoc pairwise comparisons showed that f0 differences in pairs between aspirated and tense stops were statistically significant at 20 and 40 ms but not significant at 0, 60, 80, and 100 ms. In other words, f0 differences between aspirated and lax stops are maximized whereas those between aspirated and tense stops are merged.

Second, with respect to the magnitude of the effect of the phonation type, the mean f0 difference between aspirated and lax onsets is about 80 Hz. Corresponding to the previous results in Figure 3, f0 contours following three phonation types dynamically fall into the two f0 or tonal groups: lax stops were correlated with L tone whereas tense/aspirated stops were correlated with H (Jun, 1993; M.-R. Kim, 2000). This spectral (Hz) and temporal (ms) magnitude of the effect of the phonation type on f0 held across the entire syllable, supporting that L tone conditioned by initial lax onsets and H tone conditioned by initial aspirated and tense onsets (Gim, 1969; Jun, 1993, M.-R. Kim, 2000). The effect was proposed as an onset-tone interaction (M.-R. Kim, 2000; cf. Jun 1996).

Third, the typical patterns described above for the pooled data held well for the individual speakers, although there is some individual variations when comparing the nature of the effect. In order to see how phonation types are grouped in terms of f0 contours, the individual plots of mean f0 contours according to the three phonation types are given in Fig. 8.

With respect to the nature and magnitude of the effect of the phonation type on f0, there were some individual differences. Compared with speaker 2, speaker 1 and 3 had greater f0 differences between aspirated and lax onsets throughout the six temporal locations (Masp-lax: 83 Hz for speaker 1, 71 Hz for speaker 2, and 90 Hz for speaker 3). In contrast, compared with speaker 2, speaker 1 and 3 had smaller f0 differences between aspirated and tense onsets throughout the six temporal locations (Masp-tense: 23 Hz for speaker 1, 26 Hz for speaker 2, and 21 Hz for speaker 3). As a result, compared with speaker 2, speaker 1 and 3 showed greater f0 maximization between aspirated and lax onset and smaller f0 merger between aspirated and tense counterparts. Recall that speaker 1 and 3 showed a greater VOT merger between aspirated and lax onsets than speaker 2. Interestingly, unlike speaker 1 and 3, speaker 2 showed a 3-VOT and 3-f0 category.

FIGURE 8. Overall mean f0 contour according to each phonation type based on measures taken at 20 ms intervals from the onset of the first regular vocal pulse till the 100 ms into the vowel of the target syllable for individual speaker 1, 2, and 3.

The results suggest that VOT merger is closely related with f0 maximization. If one has a VOT merger, f0 differences between aspirated and lax onsets are maximized (e.g., speaker 1 and 3). However, if one does not have a VOT merger clearly, f0 differences between the two stops are less maximized (e.g., speaker 2). If this is correct, we can say that individuals play an active role in actuating and propagating sound change. The results suggest that Speaker 1 and 3 are undergoing a sound change actively, characterized by both VOT merger and f0 maximization whereas speaker 2 less actively.

The current results on f0 can be comparable with Han & Weitzman’s (1970) results presented in Figure 3 in two aspects. First, f0 differences between aspirated and lax onsets (i.e., f0 maximization) in the current data were greater than those in Han & Weitzman’s (40 Hz vs. 80 Hz difference for Masp-lax). Second, f0 differences between aspirated and tense onsets (i.e., f0 merger) in the current data were greater than those in Han & Weitzman’s (9 Hz vs. 21~26 Hz difference Masp-tense). For the results, we can expect that, owing to the complete or partial VOT merger, f0 differences in the vocalic portion are maximized to contrast aspirated and lax onsets.

The results in the current study show that the aspirated and lax stops in Seoul Korean are undergoing a sound change, characterized by a VOT merger and f0 maximization between the two stops: VOT differences between the lax and aspirated stop in the consonantal portion are neutralized whereas their f0 differences in the vocalic portion are maximized to distinguish the lax stop from the aspirated stop. The process of a sound change in Seoul Korean is similar to tonogenesis, characterized by the loss of a consonantal opposition and the creation of tonal differences. If the sound change in Seoul Korean belong to tonogenesis, a couple of questions arise: what factor does initiate the sound change and how tonogenesis can accounted for. Since the present results are from three Seoul speakers’ productions, however, further quantitative study about interspeaker variation in sound change in Seoul Korean is necessary to generalize.

4. Conclusion

The present study investigates the pooled and individual effects of the phonation type on VOT and f0. The results are summarized in terms of the VOT merger and f0 maximization between the lax and aspirated stop. First, VOT values between aspirated and lax stops are apparently merged. The types of the merger slightly differ from speaker to speaker. Speaker 1 and 3 show a complete VOT merger (asp=lax for speaker 1 or asp < lax for speaker 3) whereas speaker 2 shows a partial VOT merger. Second, f0 values between aspirated and lax stops are maximized to contrast the two stops. The f0 maximization holds well for across speakers with some interspeaker variation in terms of the magnitude of the effect of phonation type on f0 contour. Mean f0 differences between the two stops are greater for speaker 1 and 3 than speaker 2. In contrast, mean f0 differences between aspirated and tense stops for speaker 1 and 3 are smaller than for speaker 2. The results suggest that the two acoustic parameters, VOT and f0, are closely related with each other in terms of VOT merger and f0 maximization among the three phonation types: the more VOT merger, the more f0 maximization. With respect to the VOT merger and f0 maximization, the present data can be comparable to Han & Weitzman’s (1970) data where there is little VOT merger and f0 maximization between the lax and aspirated stop and there is less interspeaker variation on the phenomena. The merger is due to the fact that there is a shortening process for the aspirated stop but a lengthening process for the lax stop. Individual differences in sound change suggest that the process is still undergoing. Some speakers might be more active initiators and propagators in sound change than others (i.e., innovators in sound change).

Because of the VOT (i.e., aspiration) merger and f0 maximization between the aspirated and lax stop in initial position, as suggested by Kim et al (2002), it is now clear that, in Korean, f0 (or tone) plays more important role in contrasting the two stops than VOT as presented in (2).

Orthography	Phonetic/Tone	Gloss

(2)   탈	[thal]	H	‘mask’

달	[thal]	L	‘moon’

In initial position, for the aspirated and lax stop, the loss of a consonantal opposition occurs in that both aspirated and lax stop carry the same amount of aspiration whereas the tonal differences in the vocalic portion are maximized. The process is analogous to tonogenesis, characterized by an onset-tone interaction (i.e., tonal differences arise because of onset consonants) and the loss of a consonantal opposition (i.e., onset differences are neutralized but tonal differences alone become contrastive). As seen in (2), the lax stop is heavily aspirated in initial position. However, it is still phonetically voiced in medial position (e.g., [ibul] ‘blanket’).

Concerning the phonetic behavior of the lax stop (aspiration in initial position but voicing in medial position), it is hard to explain why its sound change is undergoing that way (M.-R. Kim, 2012a and 2012b for some discussion). Related with the ongoing process of the sound change in Seoul Korean, many issues on the phonetic behavior and phonological explanations of the Korean stops still remain unsolved. Further studies are necessary to account for relationship between tonogenesis and the process of a sound change in contemporary Korean better.

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Mi-Ryoung Kim

Department of Practical English

Korea Soongsil Cyber University

Jongno Biz-Well 23, Samil-daero 30-gil, Seoul 110-340, Korea

Phone: 82-2-708-7845

Email: kmrg@mail.kcu.ac

Received on March 31, 2013

Revised version received on May 10, 2013

Accepted on May 23, 2013