The National Institute on Deafness and Other Communication Disorders
estimates that approximately7.5 million persons
in the United States
suffer from some sort of voice disorder. The negative impact of a voice
disorder is often social, psychological, professional, and economic (as
in the case of a singer or actor).
Voice is typically described in terms of three characteristics:
pitch, intensity, and quality. Pitch may be described as the relative
tone of a person''s voice—how high or low it is, how monotonous, or how
it demonstrates repeated
inappropriate pitch patterns. A disorder may
result from pitch being inappropriate for an individual''s age and
gender. An inability to perceive pitch and pitch patterns may result in
a monotonous voice, a high-pitched voice, or inappropriate use of
repeated pitch patterns.
Loudness describes the volume or intensity of a person''s voice. A
person who spends a great deal of time in a noisy location or who is
suffering from
hearing loss may speak with high intensity, or
louder than normal. A soft or inaudible voice may be associated with a
psychological condition such as shyness or with a structural defect of
the vocal cords.
Some disorders of voice quality are related to how the vocal cords
function: breathiness is caused by vocal cord vibration that does not
have a closed phase, while hoarseness is caused by vocal cords that are
closed too tightly, so they cannot vibrate properly. Other disorders
are related to how the voice resonates in the oral (mouth), nasal
(nose), and pharyngeal (throat) cavities. If the nasal passage becomes
blocked such as with a cold, then air is unable to reach the nasal
cavity and a voice sounds hyponasal. Hypernasality results when too
much air passes through the nasal cavities during phonation or when
there is an obstruction in the anterior nasal cavities (pinching the
nostrils).