All cues are not created equal: the case for facilitating the acquisition of typical weighting strategies in children with hearing loss.

Abstract

One task of childhood involves learning to optimally weight acoustic cues in the speech signal in order to recover phonemic categories. This study examined the extent to which spectral degradation, as associated with cochlear implants, might interfere. The 3 goals were to measure, for adults and children, (a) cue weighting with spectrally degraded signals, (b) sensitivity to degraded cues, and (c) word recognition for degraded signals. Twenty-three adults and 36 children (10 and 8 years old) labeled spectrally degraded stimuli from /bɑ/-to-/wɑ/ continua varying in formant and amplitude rise time (FRT and ART). They also discriminated degraded stimuli from FRT and ART continua, and recognized words. A developmental increase in the weight assigned to FRT in labeling was clearly observed, with a slight decrease in weight assigned to ART. Sensitivity to these degraded cues measured by the discrimination task could not explain variability in cue weighting. FRT cue weighting explained significant variability in word recognition; ART cue weighting did not. Spectral degradation affects children more than adults, but that degradation cannot explain the greater diminishment in children's weighting of FRT. It is suggested that auditory training could strengthen the weighting of spectral cues for implant recipients.