Effect of Spectro-Temporal Enhancement on Speech Perception in Individuals with AD

Abstract

Auditory dys-synchrony (AD) is a unique disorder which presents itself with impaired speech understanding ability in the presence of relatively spared audibility. The management options for individuals with AD are hearing aids and/or a cochlear implant. Although the listening devices helps these individuals to communicate, the improvements observed are not consistent across individuals. There is a need to see if there are other management options like speech enhancement that can improve speech perception in individuals with AD. Thus in the present study, two types of enhancement strategies (companding and consonant enhancement) were taken to see if they bring about any change in speech intelligibility. To analyse the same, consonant identification scores were obtained from two groups of individuals (10 individuals with AD and 10 individuals with normal hearing sensitivity) in different signal to noise ratio. Individuals with AD showed a significant improvement with companding when compared to unprocessed condition only in quiet situation. However with consonant enhancement, the improvement noticed was not statistically significant. In contrast, normals did not show any advantage with processed stimuli when compared to unprocessed condition across different signal to noise ratios. Sequential Information Transfer Analysis for AD revealed that the information transmitted was most for manner feature followed by place and voicing features. The improvement following enhancement are probably due to the increase in the spectral contrast of the speech stimuli. The improvement in the contrast might have helped the individuals with AD to extract the acoustical cues available and aided speech perception.