Voiced and voiceless stops: Differences in VOT and closure length producedby Italian deaf children

This experimental research investigated the production of the voiced and vo iceless stops /b d g/ and /p t k/ in initial and intervocalic position by f our Italian children affected by congenital and profound hearing loss. The behaviour of the glottal valve and supraglottal articulators as well as the temporal coordination between the glottal and upper airway mechanisms in s tops were analyzed from an acoustic point of view. Because glottal vibratio ns were never detected during the oral closure of voiced stops, VOT and clo sure durations were measured. Differences in VOT duration seemed to be more relevant in characterizing the voiced/voiceless opposition for stops in in itial than For those in intervocalic position. For intervocalic stops, if t he closure durations differed across the voiced and voiceless cases the VOT values remained essentially constant, but if the closure durations were co nstant, the VOT values differed. This indicates that our subjects possess i n their linguistic code the voiced/voiceless phenological opposition and co nsequently the task of the hearing teacher is of great importance.