Dissertation Defense: GaYeon Son

Feb 10, 2017 at - | Seminar room of the Linguistics department: 3401-C Walnut Street, Suite 300; Room 326

Title: Interactive development of F0 as an acoustic cue for Korean stop contrast
Supervisor: Mark Liberman
Committee: Gene Buckley, Daniel Swingley, Jianjing Kuang

TIme: February 10th, Friday, 1:30pm
Location: The linguistics seminar room


A number of studies have investigated the role of Voice Onset Time (VOT) in the acquisition of stop voicing contrast. Korean stop contrasts (lenis, fortis, and aspirated), however, cannot be differentiated using only VOT since they are all pulmonic egressive voiceless. Because of this, it is necessary to use another acoustic parameter, fundamental frequency (F0), to distinguish between Korean stop contrasts. The present study explores how F0 is perceptually acquired and how it phonetically operates in relation to Korean stop contrasts according to age. In order to determine the relationship between F0 developmental patterns and age in child stop production, this study uses a quantitative acoustic model to examine the word-initial stop productions of 58 Korean monolingual children aged 20 to 47 months. The production experiment confirmed that VOT is useful for distinguishing fortis stops, but is not as useful for distinguishing between lenis and aspirated stops. Hypothesizing that F0 at vowel onset can be used to determine significant phonetic differences between lenis and aspirated stops, two sets of synthesized lenis stimuli with different F0s at vowel onset were prepared for a perceptual identification test. Children were provided with selected lenis-aspirated pairs of images in which they would point to one or the other image in response to a given stimulus. This allowed us to observe how perceptual F0 thresholds for aspirated stops change with age. A comparative analysis between children’s speech production and perceptual patterns of F0 indicates that stability in response to F0 changes increases with age and that articulatory skills depend on perceived F0 differences depending on the phonemic boundaries. Additionally, a multilevel regression model indicates that the phonetic differentiation between the two stop manners using F0 was significantly related to age. These findings suggest that phonemic categorization of lenis and aspirated stops should be processed in the F0 dimension and that phonemic processing in perceptual acoustic space is directly linked to phonetic discrimination between the non-fortis stops in production. This study provides experimental evidence for further understanding how native phonological contrasts are acquired by young children.