Voices in noise or noisy voices: Effects on task performance and appreciation

Résumé

Learning from orally presented information often requires distinguishing target signals from noise. Effects of background noise on information processing has been extensively studied, and it is clear that similarity between target and noise makes separation more difficult. Therefore, the question is what happens when noise is actually part of the target signal, which is the case for dysphonic voices. Dysphonia is defined as a speech disorder `characterized by the abnormal production and/or absences of vocal quality, pitch, loudness, resonance, and/or duration, which is inappropriate for an individual's age and/or sex.' (ASHA).
In this study, information processing is investigated in two noise conditions that are thought to be very challenging: multitalker babble and dysphonic voices. The aim is to compare the effect of a noise source that is very similar to the target signal (speech) but clearly external, with the effect of noise sources that are inherently part of the signal (dysphonia). In addition, the combined effect, i.e. a dysphonic voice in multitalker babble, is studied as well. For information processing, task performance and subjective perception of difficulty are evaluated.
Subjective perception varies most clearly with the different noise conditions. Reported difficulty increases significantly for multitalker babble and dysphonia separately, both compared to a healthy voice in quiet conditions. Remarkably, within multitalker babble no differences in rating between dysphonic voices and the healthy voice are seen; dysphonic voices  are no longer rated more difficult than a healthy voice when this healthy voice is also presented within babble noise.