Comparison of Short-Term and Long-Term Variability in Nasalance Scores

Objective: To evaluate long-term nasalance score variability while accounting for short-term variation associated with subject performance and headgear change variability. Stimuli: Turtle and Mouse Passages. Design: Short-term immediate test-retest nasalance score variability was assessed with no headgear change (NCHG) and with change of headgear (CHG). Long-term variability was assessed with scores obtained in the morning and afternoon of the same day, 1 day apart, and 1 week apart. Scores from the long-term conditions necessarily reflect variability associated with headgear change plus variability, which may be attributed to time. Participants: Twenty-six adults (19 to 70 years of age) with normal speech and resonance. Main Outcome Measures: Forty-six nasalance scores per subject. Results: Mean nasalance difference scores across conditions were compared. Three contrasts were significantly different, each involving comparison of nasalance difference scores in the NCHG condition to difference scores from a CHG condition. Overall, long-term variability was slightly greater than short-term variability. For the Turtle Passage, in the short-term CHG condition, 92% of repeated scores were within five points. In the long-term conditions, 83% to 89% of scores were within five points. For the Mouse Passage, 88% of repeated scores in the CHG condition were within five points. In the long-term conditions, 81% to 83% of scores were within five points. Conclusions: Nasalance scores obtained over time showed slightly greater variability than scores obtained in immediate test-retest conditions; however, variability did not increase as the length of time between measures increased.