Glottal Stop in Hiatus: An Acoustic Investigation in Persian

One of the strategies to resolve hiatus in Persian is glottal stop (GS) insertion between two adjacent vowels (Sadeghi, 2001: 27, 28) [1]. This paper investigates the presence of GS in hiatus within and across morpheme boundaries in isolated words (684 tokens) as well as in words within sentences (276 tokens). Four speakers of standard Persian (two females and two males) between the ages of 31 and 37 participated in this study. Acoustic analysis of the data by Praat [2] showed three acoustic correlates of GS in intervocalic environments; in addition to a complete glottal closure and release (GC) and creaky voice (CV), completely irregular vibration of vocal folds (CIVV) was also observed. CV was characterized by a low fundamental frequency, a semi-periodic waveform and a decreasing intensity level, while no fundamental frequency, an aperiodic waveform and a descending intensity level characterized CIVV. The majority of GS presence was observed where a derivational prefix and a base had conjoined (11.9% GC, 27.38% CV and 55.95% CIVV). The significant outcome of data analysis in other morpheme boundaries and in simple words showed that GS did not exist/insert in hiatus in a great number of data; in 77.30% of isolated tokens and in 79.71% of in-the-context tokens two neighboring vowels in sequence were observed showing formant transition. This considerable number of data demonstrated that in standard formal Persian it is more probable to have two adjacent vowels in simple words and in morphological boundaries (except in derivational prefix + base environment) than to insert a GS.