nasalance

Nasalance is a measure used in speech-language pathology to quantify the amount of acoustic energy emitted from the nasal cavity during speech relative to the combined oral and nasal energy. It provides an index of nasal resonance and velopharyngeal competency. Nasalance is expressed as a percentage; nasalance score = nasal energy / (nasal energy + oral energy) × 100. A higher score indicates greater nasal resonance.

Measurement is performed with a nasometer, a device that uses two microphones and a headset to separately record nasal and oral acoustic energy while the speaker reads aloud. The procedure commonly uses standardized speech passages that elicit varying resonance, such as language-appropriate texts designed to be oral- or nasal-heavy; in some languages, equivalent normative texts are used. The resulting nasalance scores typically range from 0 to 100 and must be interpreted in the context of language- and population-specific normative data.

Clinical applications include assessment of velopharyngeal insufficiency or dysfunction in individuals with cleft palate or craniofacial anomalies, evaluation of resonance in dysarthria or apraxia, postoperative monitoring after palate surgery, and biofeedback in therapy. Nasalance is one facet of resonance assessment and should be considered alongside perceptual judgments, aerodynamic measures, and imaging. Limitations include influence of articulation, speech rate, nasal obstruction, sensor placement, and device calibration; norms vary by language, age, and task; it does not directly measure velopharyngeal closure.