Assessment of Spectral and Temporal Resolution in Cochlear Implant Users Using Psychoacoustic Discrimination and Speech Cue Categorization

Abstract

Objectives This study was conducted to measure auditory perception by cochlear implant users in the spectral and temporal domains, using tests of either categorization (using speech-based cues) or discrimination (using conventional psychoacoustic tests). We hypothesized that traditional nonlinguistic tests assessing spectral and temporal auditory resolution would correspond to speech-based measures assessing specific aspects of phonetic categorization assumed to depend on spectral and temporal auditory resolution. We further hypothesized that speech-based categorization performance would ultimately be a superior predictor of speech recognition performance, because of the fundamental nature of speech recognition as categorization. Design Nineteen CI listeners and 10 listeners with normal hearing (NH) participated in a suite of tasks that included spectral ripple discrimination (SRD), temporal modulation detection (TMD), and syllable categorization, which was split into a spectral-cue-based task (targeting the /ba/-/da/ contrast) and a timing-cue-based task (targeting the /b/-/p/ and /d/-/t/ contrasts). Speech sounds were manipulated in order to contain specific spectral or temporal modulations (formant transitions or voice onset time, respectively) that could be categorized. Categorization responses were quantified using logistic regression in order to assess perceptual sensitivity to acoustic phonetic cues. Word recognition testing was also conducted for CI listeners. Results CI users were generally less successful at utilizing both spectral and temporal cues for categorization compared to listeners with normal hearing. For the CI listener group, SRD was significantly correlated with the categorization of formant transitions; both were correlated with better word recognition. TMD using 100 Hz and 10 Hz modulated noise was not correlated with the CI subjects’ categorization of VOT, nor with word recognition. Word recognition was correlated more closely with categorization of the controlled speech cues than with performance on the psychophysical discrimination tasks. Conclusions When evaluating people with cochlear implants, controlled speech-based stimuli are feasible to use in tests of auditory cue categorization, to complement traditional measures of auditory discrimination. Stimuli based on specific speech cues correspond to counterpart non-linguistic measures of discrimination, but potentially show better correspondence with speech perception more generally. The ubiquity of the spectral (formant transition) and temporal (VOT) stimulus dimensions across languages highlights the potential to use this testing approach even in cases where English is not the native language.

High- and Low-Performing Adult Cochlear Implant Users on High-Variability Sentence Recognition: Differences in Auditory Spectral Resolution and Neurocognitive Functioning

“…Differences in auditory sensitivity to spectral and temporal properties of speech and/or neurocognitive skills between high and low performers may lead them to adopt different perceptual strategies. Indeed, there is some evidence that CI users demonstrate individual differences in their perceptual strategies, such as the weights they assign to spectral and temporal cues (Winn et al; 57 Bhargava et al; 4 Moberly et al) 34 , resulting in group differences not only in speech recognition accuracy but also in the underlying mechanisms. Although previous research has assumed that both auditory sensitivity and neurocognitive functioning contribute to speech recognition performance in CI users (e.g., Bhargava et al) 4 , these factors may not contribute equally to performance differences among high and low performers.…”

Age-Related Differences in the Processing of Temporal Envelope and Spectral Cues in a Speech Segment

“…Since the spectral resolution of a CI is poor (Friesen et al 2001), CI users likely rely on temporal information more than normal-hearing (NH) participants (Winn et al 2012; Winn et al 2016). Because CI users weight temporal cues more heavily than NH listeners, older CI users with relatively poor temporal processing abilities may be at risk for poor speech perception.…”

Multidimensional Timbre Spaces of Cochlear Implant Vocoded and Non-vocoded Synthetic Female Singing Voices

“…At the central processing level, there may be extensive changes in the brain as a result of auditory deprivation (Stropahl et al, 2017) as well as altered general cognitive abilities (Holden et al, 2013;Kramer et al, 2018). Therefore, even though timbral cues might be preserved by the initial cochlear implant signal processing, the extent to which each CI user can make use of these cues (i.e., perceptual weighting) may be highly variable (Winn et al, 2016).…”