Comparison of Nasalance Values obtained from Nasality Visualization System and Nasometer II

Abstract

This study was designed to compare nasalance scores obtained with the Nasality visualization system (NVS) and Nasometer II (NM), and to evaluate test-retest reliability of nasalance scores on each of these instruments. Twenty two adult females, without any resonance or articulation disorders, in the age range of 17 to 25 years were considered for the study. Nasalance values were obtained using NVS and NM for the stimuli vowels (/a/, i// and /u/), syllables (/pa/, /ta/, /ka/, /ba/, /da/ and /ga/), eight oral and eight nasal sentences. Following familiarization task, the participants were instructed to read the stimuli with the headset/separator handle for the actual recording. Results indicated trends of increase in nasalance values with increase in vowel height, place of articulation moving backward in the oral tract, and voicing. Paired sample t test revealed significant difference between the nasalance measured by NVS and NM instruments across all the stimuli at p < 0.05 level of significance. Chronbach’s alpha revealed good test retest reliability for both NVS and NM for most of the stimuli (α > 0.70). From the findings of the study it may be concluded that nasalance values obtained from the Nasometer II and Nasal visualization system are not interchangeable and cannot be compared directly. The normative data, cutoff scores, sensitivity, specificity and other data of NM might not be applicable to nasalance values obtained from NVS and therefore, has to be established separately for NVS. Good test retest reliability obtained in the present study for NVS makes it a reliable nasalance measuring tool for clinical and research purposes. However, further studies investigating diagnostic efficacy using clinical population and correlations of perceptual analysis of nasalance might verify the validity of this instrument.