ABSTRACT
A voice disorder exists when the loudness, pitch, quality and functionality such as voice projection and prosody differ from the voices of others of the same sex, similar age, build, dialectal and cultural group, or when the voice has changed from that which was previously deemed normal for this particular speaker. The range of electronic instrumentation, developed specifically for, or adapted to, the field of voice assessment has grown. Referrals for voice assessment and speech-and-language-therapy opinion are made to clinics from a variety of agencies, clinical and non-clinical. In clinical practice, there is a plethora of labels used to describe abnormal voice usually based on the perceptual attributes of the voice. Generally, the fundamental frequency of the human voice descends with age, relating to the enlargement of the larynx, its descent in the neck, and respiratory development. Quality is the most difficult vocal parameter to quantify.
