Resonance refers to the way that air is shaped as it passes through the mouth and nose while speaking. The air for m, n, and 'ng sounds should be directed through the nose. For all other sounds, the soft palate (in the back of the roof of the mouth) moves up and back to close off the nasal cavity so that air is directed through the mouth. If this closure, called the velopharyngeal valve, is impaired in any way, resonance disorders may result. Incomplete closure (also called velopharyngeal insufficiency or VPI) may occur because of structural abnormalities; for example, openings due to cleft palate, obstructions due to enlarged adenoids or swollen nasal passages, or a short palate. It may also occur when there are problems with palatal movement, such as weakness, paralysis, or incoordination caused by neuromuscular diseases or injuries.
Symptoms of Resonance Disorders
Symptoms range from mild to severe. If they are severe enough, they may make speech hard to understand. They include:
- An overly nasal sounding voice (hypernasality)
- Air audibly leaking through the nose during speech (nasal emission)
- A voice that sounds less nasal than usual (hyponasality or denasal), similar to when one has a severe cold (e.g., My nose is stuffy sounds like By doze is stuffy.)
Assessing and Treating Resonance Disorders
An ear, nose, and throat doctor (ENT) and sometimes a neurologist, should complete an exam in addition to the speech-language pathologist's (SLP) evaluation. The ENT will determine the structural integrity of the nasal, oral, and laryngeal cavities. A scope (thin tube with a camera) may be inserted through the nose to look at the movement of the soft palate and walls of the throat.
The SLP will first take a thorough medical history, including questions about allergies, throat and ear infections, and injuries. She will assess resonance as the client says different sounds, words, and phrases. The SLP may use specialized devices to take quantitative measures of resonance or nasal emission.
Treatments for resonance disorders will depend upon the diagnosis. The SLP may give exercises to improve strength or coordination of the movements of the palate and walls of the throat. The client may practice sensing the position of the palate and adjusting its movement during various speech tasks. Special instruments and computer programs can provide visual feedback about resonance output for this same purpose.
Sometimes medical treatments by a doctor are necessary. These include medications to treat allergies, surgeries to repair cleft palate or soft palates that are too short, surgeries to remove enlarged adenoids, and fitting of prosthetic devices worn in the mouth to help close off the opening between the nose and throat.