The effect of filtering on auditory-perceptual ratings of severity in hypofunctional voices

Abstract

Voice disorders can have a negative impact on communication. Voice quality is largely a perceptual phenomenon whose judgment relies on the subjective assessment of a listener. Mechanical devices have been developed to augment the voice and improve vocal quality in certain voice disordered individuals. The purpose of this study was to investigate whether signal modification, characterized by amplification alone, filtering alone and/or filtering with amplification, will have an effect on perceived severity of voice quality in breathy voices. Hypofunctional voices were manipulated into four conditions (Original recordings, Amplitude reinforced, Low Pass Filtered, and Low Pass Filtered with Amplitude Reinforcement). Results indicated that a significant main effect was not present (F[3,27] = 2.73, p = 0.64). Pairwise comparisons revealed that this effect was due to a significant difference between the severity ratings for the OR and the LPF stimuli (mean difference = 3.96, p = .037, 95% confidence interval = .296 - 7.629). The results indicate that there was an effect when low pass filtering was present. This condition would help the perceptual quality of a hypofunctional voice if used in an external mechanical device.