Cognitive performance and perceived effort in speech processing tasks: effects of different noise backgrounds in normal-hearing and hearing-impaired subjects.

Cognitive tests of speech understanding were administered (presented as text, or in auditory or audiovisual modality) and perceived effort was rated. This was done in four background conditions: in silence, and in three types of noise (S/N=+10 dB) varying in temporal structure and meaningfulness. Four groups of 12 subjects each (young/elderly with normal hearing and young/elderly with hearing impairment) participated. The presence of noise had a negative effect on accuracy and speed of performance in the speech processing tasks, and resulted in higher scores of perceived effort, even when the stimuli were presented as text. Differences in performance between noise conditions existed. In the subjective scores, the noise with temporal variations, but without meaningful content, was the most disruptive of the three noise conditions. In the objective scores the hearing-impaired subjects showed poorer results in noise with temporal variations. The elderly subjects were more distracted by noise with temporal variations, and especially by noise with meaningful content. In noise, all subjects, particularly those with impaired hearing, were more dependent upon visual cues than in the quiet condition.