Nasality in modal speech and twang qualities: Physiologic, acoustic, and perceptual differences

The habitually confused voice quality terms, nasality and twang, were clarified in two experiments examining physiologic, acoustic, and perceptual distinctions between voice quality combinations of nasality in modal speech and twang. In experiment 1, physiologic and acoustic differences between oral speech, nasal speech, oral twang, and nasal twang were investigated. The results showed that instrumentally validated productions of each voice quality originated at the velopharyngeal port, whereas twang originated at the aryepiglottic sphincter. These physiologic manipulations generated characteristic acoustic differences in format frequency and amplitude shifts. The most significant shifts occurred for frequency at F1 and for amplitude below 1000 Hz (p<0.05). In experiment 2, perceptual distinctions among the voice qualities were identified by naive listeners, music majors, and speech pathology majors. Results of this experiment showed that the listeners perceived four distinct voice qualities by identifying them significantly above the level of chance (p<0.05).