ACOUSTIC THEORY OF SPEECH PRODUCTION ... - Ling.cam.ac.uk

More documents

Recommendations

Info

12 of 20 Paper 9 etc: AcThSpProd Figure 14: Model for [i] g c l g l c glottis lips point (or region) of maximum constriction [i] Lb Lf F1 is a Helmholtz resonance. (“Bottle-shaped” tube, with a single low resonance.) Higher formants: back cavity: closed-closed; front cavity: open-open. Lb = 9 cm c/2l 34000/18 = 1890 Hz Lf = 8 cm 34000/16 = 2125 Hz These formants are raised further in frequency because the back cavity is tapered towards the constriction, and a tapered end raises resonance frequencies. N.B. If you start calculating formant frequencies to see if you understand, don't give up if your answers don't match real speech well. Rather, talk with your supervisor. Your calculations may be right, but a number of adjustments have to made to match real speech (like fat in the cheek walls, warm moist air, overall VT shape in some special cases......). 7.1.2 Obstruents Figure 15. Model for [s] [s] Lb Lc Lf Three cavities (tubes): • back cavity: closed-closed • constriction: open-open • front cavity: closed-open. Lc = length of constriction (when it’s long enough, it acts as another tube with its own resonances) The back cavity is excited relatively little by a supralaryngeal noise source, and the amplitudes of its resonances are further reduced by antiformants (zeros) arising from interactions between front and back cavity resonances. Therefore, the back cavity contributes little to the output. Greater accuracy is achieved when other factors are taken into account (eg length of constriction, shape of back cavity near constriction, wall compliance, whether the airstream hits a sharp edge like teeth). M4_0708_AcousticTheorySpeechProduction_07-8.doc
Paper 9 etc: M4_AcThSpProd 13 of 20 Thus, for a voiceless obstruent like [s], source and transfer functions combine as in Figure 16 amp Noise source (supralaryngeal except for [h] ) frequency amp Transfer function (for the [s] vocal tract shape shown above) frequency amp Radiation function (+6 dB per octave) log. frequency amp Output spectrum frequency M4_0708_AcousticTheorySpeechProduction_07-8.doc
Page 1 and 2: LT 9, MML Li9, MPhil Foundations of
Page 3 and 4: Paper 9 etc: M4_AcThSpProd 3 of 20
Page 11: Paper 9 etc: M4_AcThSpProd 11 of 20

ACOUSTIC THEORY OF SPEECH PRODUCTION ... - Ling.cam.ac.uk

Create successful ePaper yourself

Delete template?

Save as template?