What is Nasometry?
When we speak, varying amounts of air are released from our nose and our mouth. The ratio between the two can depend on several factors including what language is being spoken, what specific phonemes are being produced, or the effectiveness of velopharyngeal closure.
The nasometer is a computer-based instrument that compares the relative amount of oral and nasal acoustic energy (that is, how much air is being released from each location) when a person speaks.
Source: Kummer, A. W. (2008). Nasometry. Cleft Palate and Craniofacial Anomalies: Effects on Speech and Resonance, ed, 2, 376-414.
The Nasometer
A computer based system, the Nasometer allows clinicians to measure the relative amount of oral and nasal acoustic energy in an individual’s speech. Standardized passages for different languages have been produced to elicit different nasal environments (e.g., non-nasal pressure consonants or nasal consonants only).
With the device, nasal (N) and oral (O) acoustic components of a subject’s speech are sensed by microphones separated by a horizontal head set-mounted sound separator that rests on the upper lip.
The signal from each of the microphones is filtered and digitized by custom electronic modules. The data can then
be processed by a personal computer and displayed in real-time on a computer screen. The resultant signal is a ratio of nasal-plus-oral acoustic energy. The ratio is multiplied by 100 and expressed as a percentage “nasalance” score. Specifically, the nasalance score can be described thusly:
Nasalance = N ÷ (N + O) x 100.
Sources: Dalston, R. M., & Seaver, E. J. (1992). Relative values of various standardized passages in the nasometric assessment of patients with velopharyngeal impairment. The Cleft Palate-Craniofacial Journal, 29(1), 17-21; Kummer, A. W. (2008). Nasometry. Cleft Palate and Craniofacial Anomalies: Effects on Speech and Resonance, ed, 2, 376-414.