Development of an Ergonomic Nasometer

Abstract

Resonance disorder occurs in 20% to 30% of individuals who have undergone cleft palate repair and in 5% to 10% of patients with a submucous cleft palate. Assessment of resonance disorder is conducted by evaluating the degree of nasality. Nasalance, a measure of degree of nasality, can be obtained by calculating the ratio of nasal sound energy to total of nasal-oral sound energy. Kay Pentax Nasometer has become a golden standard device to measure nasalance and has been widely used among therapists. The nasometer utilizes two microphones separated by a metal plate, which are attached to a head gear, to capture nasal sound energy and oral sound energy separately. However, the present nasometer needs several improvements in terms of non-intrusiveness, wearability, portability, and affordability. The main objective of this study is to propose and evaluate an ergonomic device to measure nasalance compared with nasometer for speech assessment and speech therapy. The ergonomic nasometer is proposed after determining the best layout and conditions of tool for nasality measurement including microphone position, microphone distance to mouth and nose, and separator distance to philtrum. The proposed nasometer uses a 5 mm gap distance between separator and lip (untouched separator) for non-intrusiveness to mouth movement, while maintaining the sensitivity of measurenment. Adjustment multiplication factors for nasal (1.08~1.34) and oral (0.23~0.85) are implemented to the proposed nasometer system in order to get equivalent results with the existing nasometer.