Features of nasals Vocal tract longer than for oral sounds – ↓ resonant (formant) frequencies – Nasal formant/murmur Nasal cavity is acoustically absorbent – Attenuates overall energy – Acts as a low-pass filter Pharyngeal/oral cavity acts as a “cul-de-sac” – Introduces antiresonances/antiformants Formant transitions – Varies for place of articulation
Silent gap/closure interval What is it? Period during VT occlusion Voiceless: relatively long Voiced: reduced or absent closure interval May exhibit a “voice bar” voiceless voicedvoice bar
Question How can voicing continue with a closed vocal tract?
Release burst What is it? Acoustic energy associated with VT release Transient: – ~10-30 msec Aperiodic Often absent in final position
Release burst Provides place information Spectral shape related to cavity size in front of constriction Bilabial: – diffuse energy dominant in low frequency – Either gently sloping spectrum or ~500-1500 Hz Alveolar: – diffuse energy that is dominant in higher frequencies (>4000 Hz) Velar: – compact energy in midrange (1500-4000 Hz)
Aspiration Observed in voiceless stops Consequence of air turbulence at the open glottis Increases the duration of the release burst
Voice onset time Voiceless Termed long lag VOT VOT ranges from 25 – 100 msec Voiced Short lag: – Voice onset shortly after release – VOT>0 Simultaneous voicing: – voicing and release are coincident – VOT = 0 Prevoicing/VOT lead: – voicing occurs before release – VOT <0 VOT ranges from –20 – 20 msec voiceless voiced
Voice onset time VOT may distinguish place of articulation Bilabial: relatively short VOT Alveolar: mid-length VOT Velar: relatively long VOT RULE: as the cavity in front of the occlusion gets longer, VOT increases
Voice onset time has been considered an important measure of coordination. Why?
Formant Transitions Formants of adjacent vowels will change with VT occlusion Transitions will last about 50 msec (shorter than glides/liquids) Transitions not obvious with voiceless The form of the transition is a function of – The place of articulation – The neighboring sound – F1 and F2 are the key players