A Phonetic Study of the Velar Glide [w] in Persian

Persian velar glide [w], unlike the palatal glide [j], does not serve a contrastive function in Persian phonology since it has incomplete distribution, occurring only in few words after the mid back vowel /o/. Thus, [w] is described as an allophone of the phoneme /v/. Furthermore, it has been assumed that [w] in [ow] may be deleted in connected speech giving rise to the compensatory lengthening of the preceding [o] vowel. In the present research, we examined the phonetic realization [w] in Persian words in an experimental study. The results suggested that [w] is acoustically present in the target words but is reduced or weakened to different degrees. As [w] is reduced in [ow], the shape of the vocal tract as well as the phonation type changes, resulting in (1) increase of overall intensity of the spectrum; (2) increase in the formant frequencies; and (3) decrease in bandwidths of the formant frequencies. All these systematic acoustic variations cause the vowel [o] in [ow] to be produced and perceived as longer than an ordinary [o] vowel