Instrumental assessment and treatment of hypernasality, following maxillofacial surgery, using SNORS: a single case study

Abstract

The super nasal oral ratiometry system (SNORS) is a commercially available system which measures both nasal and oral airflow during speech, allowing the very rapid movement of the velum to be measured. SNORS uses a modified oxygen mask, which houses the airflow sensors and microphones, and a standard personal computer. By calculating nasalance (the percentage of airflow that is nasal), an estimation of velopharyngeal closure, which is independent of speech intensity, is achieved. SNORS can be used for objective assessment, where the subject is required to speak a number of words selected to demonstrate velopharyngeal function. SNORS also provides biofeedback, using a simple realtime display of nasal and oral airflow. Velopharyngeal insufficiency (VPI) is the inability to make adequate velpharyngeal closure, and may be the result of either neurological or, as in this case, structural abnormalities. It results in abnormal speech characteristics, such as omissions, substitutions or weak articulation of consonants, and hypernasality. T.W., a 52 year old male, had very hypernasal speech following extensive maxillofacial surgery, for the removal of a tonsillar carcinoma. SNORS was successfully used as both an assessment and a therapy tool in the treatment of this patient. The effectiveness of conventional speech and language therapy vs. SNORS biofeedback therapy was compared. Initially, while there was some movement of the velum, the patient could not achieve velopharyngeal closure. Conventional therapy aimed to strengthen and improve the function of the velum and following this there was some minimal improvement: the patient could now achieve, but not maintain, closure. Reassessment, following a non-treatment period, showed little further change. SNORS biofeedback therapy was then given. This raised the patient's awareness of his velopharyngeal function, thus helping him to maintain closure, thereby reducing hypernasality. SNORS therapy proved significantly more effective than conventional speech and language therapy, in this case. Further intervention is outlined, and the benefits of multiparameter assessment of speech are discussed.

An instrument for the multiparameter assessment of speech

“…The University of Kent system, SNORS (Super Nasal Oral Ratiometry System), is also an anemometry system, which assesses velopharyngeal closure. However, unlike conventional nasal anemometers, SNORS measures both nasal & oral airflow, providing a much better assessment of the degree of closure 9,12 . This is achieved by calculating the percentage of airflow that is nasal, thus virtually eliminating the volume factor.…”