The Effect of Altered Auditory Feedback of Voice Focus on Nasalance Scores

Voice focus is a term that describes the perceived brightness or throatiness of the voice. In previous research, forward voice focus resulted in higher and backward focus in lower nasalance scores. This study explored whether electronically altered auditory voice focus feedback prompts speakers to adjust their voice focus and whether this affects nasalance scores. Twenty females with normal speech wore a Nasometer headset and headphones. They repeated a single sentence with oral and nasal sounds. Their auditory feedback was gradually changed with a voice transformer, so the speakers heard themselves with a more forward or backward voice focus, respectively. Oral-nasal balance was quantified as a nasalance score. Analysis of variance results of the averaged first and second vowel formants of three repetitions of the stimulus at the different baselines and maximum forward and maximum backward voice focus feedback conditions demonstrated significant effects of the voice shift condition. Analysis of variance for the nasalance scores demonstrated a significant effect of feedback condition. From the initial mean nasalance scores of 29.5%, the mean nasalance dropped to 27.5% in the backward and to 25.7% in the forward focus feedback condition. The altered auditory feedback induced voice focus adjustments that resulted in lower nasalance scores. The use of altered auditory feedback in speech therapy of hypernasality needs to be investigated in future research.