The relationship between nasalance scores and nasality ratings obtained with equal appearing interval and direct magnitude estimation scaling methods.

OBJECTIVES: To assess the nasalance/nasality relationship and Nasometer test sensitivity and specificity when nasality ratings are obtained with both equal appearing interval (EAI) and direct magnitude estimation (DME) scaling procedures. To test the linearity of the relationship between nasality ratings obtained from different perceptual scales. STIMULI: Audio recordings of the Turtle Passage.
DESIGN: Participants' nasalance scores and audio recordings were obtained simultaneously. A single judge rated the samples for nasality using both EAI and DME scaling procedures. PARTICIPANTS: Thirty-nine participants 3 to 17 years of age. Across participants, resonance ranged from normal to severely hypernasal. MAIN OUTCOME MEASURES: Nasalance scores and two nasality ratings.
RESULTS: The magnitude of the correlation between nasalance scores and EAI ratings of nasality (r  =  .63) and between nasalance and DME ratings of nasality (r  =  .59) was not significantly different. Nasometer test sensitivity and specificity for EAI-rated nasality were .71 and .73, respectively. For DME-rated nasality, sensitivity and specificity were .62 and .70, respectively. Regression of EAI nasality ratings on DME nasality ratings did not depart significantly from linearity.
CONCLUSIONS: No difference was found in the relationship between nasalance and nasality when nasality was rated using EAI as opposed to DME procedures. Nasometer test sensitivity and specificity were similar for EAI- and DME-rated nasality. A linear model accounted for the greatest proportion of explained variance in EAI and DME ratings. Consequently, clinicians should be able to obtain valid and reliable estimates of nasality using EAI or DME.