UBC Theses and Dissertations
Perception of vowel nasalization in French Lafargue, Andre Gustave
The present study investigates the perception of vowel nasalization in French. Previous studies had shown that a nasalized vowel in a non-nasalized context was produced with the velopharyngeal port closed for part of the duration of the vowel. Similarly, it was found that an oral vowel in a nasalized context was produced with the velopharyngeal port open for part of the duration of the vowel. Single cycles were spliced out of vowels of both types at times corresponding to various and known velar heights. They were used to construct the stimuli of two listening tests. Each test also contained non-manipulated reference vowels (oral and nasalized) as controls to evaluate the listeners' responses. Native speakers of French were asked to rate, on a 5-point scale, the degree of nasality of each stimulus. There seems to exist a non-monotonic relationship between curves representing the listeners' judgement of nasality and those representing the timing of velar movement. Results also suggest that a rather large velopharyngeal cross-section may be necessary for a French listener to perceive an open vowel such as [a] as nasalized, whereas a smaller velopharyngeal cross-section may be sufficient to give a close vowel such as [e] and [o] a nasalized quality. It also appears that the listeners perform some kind of time integration of the nasality function in order to judge whether a vowel is nasalized or not. An acoustic analysis was carried out, using an analysis-by-synthesis method. It shows that different changes occur in the vowel spectrum as the velum lowers e.g., the first and second formant come close together and at least one zero is present when the velopharyngeal port is open. The position and movement of this zero in the spectrum suggest that there is a relation between the position of the zero on the frequency axis on the one hand, and size of the velopharyngeal cross-section and oral vocal tract on the other. The acoustic analysis also suggests that there exists some relation between the presence of a zero in the spectrum of vowels, the corresponding position of the velum and the perception of nasalization. Possible experiments are suggested for further research.
Item Citations and Data