Abnormal nasal resonance is frequently observed in the speech of deaf individuals. Students may have an overall resonance pattern characterized as nasal or denasal or they may have specific problems coordinating articulatory gestures with valving of the velar-pharyngeal port.
Distorted nasal resonance may be attributed to faulty control of velar-pharyngeal closure and/or to faulty movement and positioning of the tongue for vowel production. Both result in an altered resonance cavity that distorts the acoustic signal. Some surmise that this faulty resonance enhances proprioceptive feedback.
It is often difficult to determine how a student is creating a particular resonance pattern. This makes remediation a challenging and difficult task, especially if the student is unable to capitalize on auditory feedback to monitor performance.
We have found that students may utilize visual feedback regarding acoustic characteristics of their speech. For example, they may see a dampening of acoustic energy or distorted harmonics on a speech spectrogram. They may also use a spectrogram to monitor faulty articulatory gestures. The following examples illustrate these points.
In this segment the instructor is demonstrating how visual information may be used to instruct a student. Three student samples are displayed, showing how auditory and visual information can be used to select the best production.