An apparent-time study of an ongoing sound change in Seoul Korean: A prosodic account

Abstract

In present-day Seoul Korean, the primary phonetic feature for the lenis–aspirated stop distinction is shifting from VOT to F0. Some previous studies have considered this sound change to be a tonogenesis, whereby the low-level F0 perturbation has developed into tonal features (L for the lenis and H for the aspirated) in the segmental phonology. They, however, have examined the stop distinction only at a phrase- or utterance-initial position. We newly explore the sound change in relation to various prosodic structural factors (position and prominence). Apparent-time production data were recorded from four speaker groups: young female, young male, old female, old male. The way the speakers use VOT versus F0 indeed varies as a function of position and prominence. Crucially, in all groups, VOT is still used for the lenis–aspirated distinction phrase-medially due to the lenis stop voicing. This role of VOT, however, is found only in the non-prominent (unfocused) condition, in which the F0 difference is reduced to a low-level perturbation effect. In the prominent (focused) context in which tones come into play, the role of VOT diminishes, led by young female speakers. These can be interpreted as a prosodically-conditioned, complementary use of the features to maintain sufficient contrast. Importantly, however, the tonal difference under focus is not bidirectionally polarized, so that F0 is not lowered for the lenis stop. A lack of direct enhancement of the distinctive L tone weakens a possibility that F0 is transphonologized to the phonemic feature system of the language. As an alternative to the view that tonal features are newly introduced in the segmental phonology, we propose a prosodic account: the sound change is best characterized as a prosodically-conditioned change in the use of the segmental voicing feature (implemented by VOT) versus already available post-lexical tones in the intonational phonology of Korean.

How does focus-induced prominence modulate phonetic realizations for Korean word-medial stops?

“…The focus effect of increasing F0 is consistent with Yun (2013) which found higher F0 for intervocalic lenis stops when phrases with the lenis stops in the phrase-medial positions were focused than when not focused. It has been also reported that F0 for both aspirated and lenis stops in word-and phrase-initial positions became higher with focus than without focus (Choi et al, 2020), demonstrating the similar focus effects on F0 between for the word-medial intervocalic stops and for the word-and phrase-initial stops.…”

“…Kang & Guion (2008), for instance, showed that young speakers increased F0 for the wordand phrase-initial lenis and aspirated stops in clear speech (i.e., foreigner-directed speech) as compared to those in conversational speech. Choi et al (2020) also showed higher F0, as well as longer VOT, for the word-and phrase-initial lenis and aspirated stops when the stops were focused than when they were not. Note that in both studies, the aspirated and lenis stops differed in the degree to which their F0 and VOT values were manipulated by clear or focused speech, and as a result, for instance, the F0 distance between the stops became larger in clear and focused speech than in convertsational and unfocused speech, respectively.…”

“…Along with the manipulations of the prominence, we compare male and female speakers to see whether and how the phonetic realizations for the stops may differ as a function of speakers' gender. A number of studies have demonstrated gender differences in VOT and F0 for lenis versus aspirated stops in word-and phrase-initial positions, with larger VOT and smaller F0 distances between the stops for males than females (Bang et al, 2018;Choi et al, 2020;Kang, 2014). Thus, to see whether there would be any gender differences for the word-medial intervocalic stops as well, we collect data from both female and male speakers.…”

The f0 perturbation effects in focus marking: Evidence from Korean and Japanese

“…Seoul Korean has been reported to show less difference in VOT between lenis and aspirated stops, but more f0 differences. It is also shown that the decrements of VOT difference and the enhancement of f0 difference were conditioned by the prominence of the syllables [ 22 ]. Specifically, they used a corrective focus task and examined disyllables.…”

“…This sound change is supported by the evidence of an increase in f0 differences and a reduction of VOT differences after lax and aspirated stops both from speech production [ 17 , 18 ] and perception studies [ 39 ]. [ 18 ] argued that the current sound change of Korean is at a stage of quasi-tonogenesis, in which the extra pitch feature is being phonologized and becoming distinctive over time [ 22 , 40 ]. The phonologization of the f0 differences is analyzed by some as phrase-initial prosodic strengthening [ 41 ] and a prosodically driven sound change [ 22 ].…”