nasometer

A nasometer is a medical instrument used in speech-language pathology to measure nasalance, the relative amount of nasal acoustic energy in speech. It combines a sampling system with microphones to separate nasal and oral sound energy as a person speaks into a mouthpiece, with a barrier that helps keep the nasal and oral channels distinct.

The device uses two microphones to capture nasal and oral signals, and a signal processor computes the nasalance score as nasal energy divided by the total energy (nasal plus oral), typically expressed as a percentage. This provides a quantitative index of resonance that can be used across tasks and language contexts.

Clinically, nasometers are used to assess velopharyngeal function and resonance disorders, such as those associated with cleft palate or velopharyngeal insufficiency. They support diagnostic evaluation, treatment planning, and monitoring of therapy outcomes, often in conjunction with perceptual assessments and imaging studies.

During testing, patients read standardized sentences or passages and repeat statements designed to sample a range of phonetic contexts. Results are compared with normative data for age, language, and dialect, informing interventions aimed at achieving appropriate nasal resonance and velopharyngeal closure.

Limitations include dependence on speech material, dialect, and calibration; nasalance reflects acoustic energy rather than direct physiological closure. High or low nasalance does not by itself diagnose a condition, and factors such as nasal obstruction or congestion can influence measurements. The nasometer has become a common, widely used clinical tool since its development in the late 20th century.