F0 perturbation effect in Initial Fricatives of Serbian – An Acoustic Analysis

The present paper explores the phenomenon of perturbation of fundamental frequency in fricative obstruents in Serbian. The recordings include two reading conditions of target tokens with initial fricative and all vowels from the Serbian phonetic inventory. Two measurements were performed on the recorded data: the first measurement includes the first five oscillating periods of the post-fricative vowel and the second every centisecond of the first 120 ms of the vowel. We explored the dependence of pitch values on underlying voicing of initial fricatives, vowel quality, place of articulation and phonological context. The quality of the vowel affects the fundamental frequency in a way that high vowels have higher f0 values and the opposite. The place of articulation is not a significant factor of f0 change. More statistically significant results were obtained in reading words in a carrier sentence than reading them in isolation. The contour of f0 is shown to be falling after voiceless, and falling or level after voiced fricatives, except one case of rising f0 after voiced fricatives. The perturbation effect is found to be 60 ms into the vowel. With this fact in mind, we concluded that f0 perturbation is utilized to enhance the voicing contrast of prevocalic fricatives. The patterning of voiceless unaspirated and voiceless aspirated consonants in other languages classifies the f0 cue as one of the [voice] rather than [spread] features.