Prosodically driven phonetic properties in the production and perception of spoken Korean
The focus of this study was to explore how prosodic position and word type affect the phonetic structure and resulting perceptual identification of Korean stops and fricatives. When there is less contextual information, speakers tend to produce clearer speech. For example, consonants at the beginning of prosodic domains, such as syllables, words or phrases, are known to be more clearly articulated and distinguishable than later-occurring consonants. However, it is not yet clear whether the prosodically conditioned realizations of a segment are perceptually distinctive in continuous speech. In addition, there are few studies examining whether the properties of prosodic domain-initial segments are affected by the information content of words (real vs. nonsense words). The acoustic properties of stops and fricatives were compared across IP, PP and Wd-initial positions both in real and nonsense words. It was found that segments in the higher prosodic domain-initial positions showed enhanced durational properties compared to the lower prosodic domain-initial positions. However, the enhancing strategies were different among phonation types. Relative to lenis and aspirated stops, and lenis fricatives, tense stops and fricatives showed less consistent variation as a function of prosodic position and word type. In the perception study, the identification error rates and reaction time for same-spliced CVs were compared to those for cross-spliced CVs. Korean listeners identified the same-spliced CVs more accurately and faster than cross-spliced CVs. In addition, the distinctive acoustic properties of each prosodic domain-initial position were perceptually distinguished by Korean listeners. Due to relatively shorter duration and less distinctive contrast, the target CVs extracted from lower prosodic domain-initial positions caused more confusion in the identification of target segments. In conclusion, this study provides the evidence that speakers modulate their speech clarity depending on information content. By enhancing phonetic properties and phonological contrast, speakers tend to provide perceptual cues for prosodic positions with less contextual information.