Voice: sound produced by the vibration of the vocal folds and modified by the resonators.
Voice disorder is defined as a disturbance of pitch, loudness or quality in relation to an individual’s age, gender and cultural background.
A voice disorder may be classified as functional or organic in nature. An organic voice disorder results from pathology or disease that affects the anatomy or physiology of the larynx and other regions of the vocal tract (i.e., cancer, vocal fold paralysis and pubertal changes). A functional voice disorder is related to vocal abuse/misuse in the absence of an identifiable physical etiology (cause) (i.e., contact ulcers, vocal nodules and vocal polyps).
Common symptoms of a voice disorder include:
- breathy voice quality
- chronic cough or excessive throat clearing
- vocal strain or fatigue
- inability to speak loudly
- loss of voice
- reduced pitch range or sudden change in overal pitch
- sudden or gradual change in overall vocal quality
- decreased breath support during speech
Resonance: refers to the way airflow for speech is shaped as it passes through the oral (mouth) and nasal (nose) cavities.
A resonance disorder occurs when there is an opening, inconsistent movement or obstruction that changes the way air flows through the system.
In normal production of voice, the airstream is generated by the lungs. As the air passes through the larynx, the vocal folds are set into vibratory motion, which results in the production of sounds (i.e., phonation). The sound continues to travel through the upper vocal tract and is modfied by the resonating characteristics of the pharynx (located above the level of the soft palate and opening anteriorly into the nasal cavity) and oral and nasal cavities.
Signs of a resonance disorder, due to an 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)
- phoneme-specific nasal emission of air (audible nasal air loss on only a few sounds (usually s and z)
Signs of resonance disorder, due to an obstruction, may include:
- hyponasality (decreased airflow through the nose due to a blockage in the nose, such as during a bad cold)
- cul-de-sac resonance (airflow through the mouth is obstructed, often by enlarged tonsils, resulting in a “muffled” speech quality)