Like articulation and phonation, resonance is a fundamental feature of speech production. Resonance is an acoustic phenomenon affected by the physical characteristics of the pharyngeal, oral, and nasal cavities. The oral, pharyngeal, and nasal cavities are tubelike structures that have specific resonance characteristics. During normal speech, the acoustic signal generated by the larynx (voiced sound) is filtered, as the articulators (lips, tongue, [Page 1611]mandible, soft palate, and pharyngeal walls) move continuously to change the shape of the oral and pharyngeal cavities. As these cavities change shape, their resonance characteristics will also change, affecting the acoustic signal that is emitted from the oral cavity. Thus, various vocal tract shapes are associated with specific voiced speech sounds such as vowels.

If the vocal tract does not allow voiced ...