Resonance refers to the way airflow for speech is shaped as it passes through the oral (mouth) and nasal (nose) cavities. During speech, the goal is to have good airflow through the mouth for all speech sounds except m, n, and ng. To direct air through the mouth, the soft palate (back part of the roof of the mouth) lifts and moves toward the back of the throat. This movement closes the velopharyngeal valve (opening between the mouth and the nose). A resonance disorder occurs when there is an opening, inconsistent movement, or obstruction that changes the way the air flows through the system.
Signs of a resonance disorder due to incomplete or inconsistent closure of the velopharyngeal valve may include:
- Hypernasality: too much sound coming from the nose during speech.
- Nasal Air Emission: air leaks through the nose while trying to build up pressure for consonant sounds.
- Weak or omitted consonants.
- Short utterance length due to loss of air through the nose.
- Compensatory speech errors.
- Phoneme-Specific Nasal Emission of Air: audible nasal air loss on only a few sounds (usually s and z). This is a result of velopharyngeal mis-learning, not a structural issue.
The most common cause of a resonance disorder is cleft palate but children with a submucous cleft palate, childhood apraxia of speech, enlarged adenoids and/or neurological disorders may also have a resonance disorder.
