Correlation of Nasal Volume and Cross-Sectional Area With Nasalance Scores as Measured by Acoustic Rhinometry and Nasometry

Acoustic rhinometry is a technique that utilizes sound waves to measure nasal patency. The reflections of the waves off of the nasal structures allow one to assess the volume and cross sectional area of the nasal cavity. It is a non-invasive procedure that can be performed in a rapid, convenient, and reliable manner. There is minimal discomfort for the patient and it can be performed easily in the office. There is no distortion of nasal anatomy or functioning as a result of the procedure.

Nasometry is a technique to measure the oral and nasal components of nasalance. Nasalance is an objective measure of the nasal component of speech that is determined by the ratio of acoustic pressures emitted from the nasal and oral cavities. 'Nasality' is the term used to characterize the nasal component of speech, and is a subjective measure.

The Nasometer (Kay Elemetrics Corp Lincoln Park, NJ) is a computer-based device that analyzes acoustic energy that is emitted from the oral and the nasal cavity during speech. It consists of two microphones that are separated by a plate. The upper microphone measures nasally emitted acoustic energy, and the lower microphone measure the acoustic energy emitted from the oral cavity.

Nasalance is an important measure in speech pathology. In situations where velopharyngeal competence is in question, nasometry objectively documents the nasal component of speech as normal, hypemasal or hyponasal. It has been found to be of tremendous benefit in the management of patients with cleft palate and velopharyngeal incompetence. The subject is relaxed, and is fitted with a headgear apparatus. This apparatus is placed such that a plate lies in a horizontal plane that rests midway between the nose and the mouth. There are microphones on the upper and lower surfaces of the plate that capture sound energy produced from the nasal and oral cavities respectively. The subject is then asked to read standard passages. The three most commonly used passages are described here, and will be used in our study. The 'Rainbow' passage is most representative of standard English speech. The 'Zoo' passage has no nasal consonants, and the 'Nasal' passage has the highest number of nasal consonants.

While the subject is reading, the microphone captures sound pressure levels which are emitted from the nasal and the oral cavities. This data is analyzed by the attached computer and presented graphically. The computer also provides a nasalance score for each of three above- mentioned passages. Normative data is available for each of these passages for adults and children. By comparing the data obtained from the subject with the normative means and standard deviations, the investigator can categorize the subject's voice as normal, hyponasal or hypernasal. The nasalance score that is generated can also be used to monitor the efficacy of speech therapy and surgical interventions.