Phonetics and Phonology (eng507)
Download 1.01 Mb. View original pdf
|
| ©Copyright Virtual University of Pakistan Phonetics and Phonology (ENG) VU Topic-122: Perturbation Theory We have discussed that the vocal tract as a tube with a uniform diameter has simultaneous resonance frequencies—several different pitches at the same time. We have also discussed that these resonance frequencies change in a predictable way when the tube is squeezed at various locations. This means that we can model the acoustics of vowels in terms of perturbations of the uniform tube. For example, when the lips are rounded, the diameter of the vocal tract is smaller at the lips than at other locations in the vocal tract. The theory of perturbation says that with the acoustic effect of constriction at the lips, we can predict the formant frequency differences between rounded and unrounded vowels. Keeping in mind this modification in the size and nature of vocal tract (for specific vowel sounds, we can estimate how this perturbation theory works. So for each formant, there are locations in the vocal tract where constriction will cause the formant frequency to rise, and locations where constriction will cause the frequency to fall. Download 1.01 Mb. Share with your friends:
|