Intensity slopes as robust measure for distinguishing glottalic vs pulmonic stop initiation

A novel cross-linguistically robust measure is introduced for the linguistically relevant distinction of pulmonic vs glottalic (ejective) stops. We propose to parametrize the abruptness of the following vowel onset by using intensity slope (RMS-trajectory) at the voicing onset. This measure was previously discussed only for voicing distinction of pulmonic stops (Harrington, 2012). The dependencies on vowel quality of the following vowel, voice onset time (VOT), phonetic prominence and speaking rate are investigated on a small-scale sample of two speakers from Avar (Nakh-Dagestanian), Ingush (Nakh-Dagestanian), and Georgian (Kartvelian). The results demonstrate robust significant differences of intensity slopes between pulmonic and glottalic stops, the latter showing the steepest slopes/the most abrupt onsets. In some cases of prevoiced stops, the intensity slopes allow even a tripartite distinction of (pre-)voiced, voiceless (aspirated), and ejective stops. However, in order to countervail the influence of vowel specific onset characteristics (e.g., degree of lip rounding) or the influence of VOT, the sample must be controlled for vowel quality and place of articulation. And, since higher speaking rates and less prominent syllables involve higher rates of laryngealized (creaky) vowel onsets, a breakdown of the abruptness distinction is observed under these conditions.