Speech-intelligibility models (SIM) can be used for systematic fitting of hearing-aids and cochlear-implants, potentially improving clinical outcomes in noisy environments. Existing SIMs are suitable for predicting performance of normal-hearing subjects, but not for hearing-impaired subjects due to our limited understanding of the effects of cochlear hearing impairment on speech-in-noise coding. In this work, we collected auditory-nerve (AN) single-unit responses and envelope following responses (EFR) in normal- and hearing-impaired chinchillas to speech, spectrally-matched stationary-noise, and noisy-speech. Our data show increased correlation between AN-fiber response envelopes of noisy-speech and noise-alone for hearing-impaired fibers in speech-relevant modulation-frequency bands, suggesting a greater degree of distraction from inherent envelope fluctuations following cochlear hearing loss. This novel finding is significant given the emphasis recent SIMs [e.g., Jorgensen and Dau, JASA (2011)] have placed on the importance of inherent noise-envelope fluctuations in addition to speech-coding fidelity in predicting noisy-speech perception. Preliminary data also show enhanced fundamental-periodicity coding at the expense of place-specific formant coding, and a degradation of burst envelopes of high-frequency fricatives for the hearing-impaired group. EFRs show evidence for degraded tonotopic coding, as observed in single-unit responses [e.g., Henry et al., J. Neurosci. (2016)]. [Work supported by Action on Hearing Loss (UK).]Speech-intelligibility models (SIM) can be used for systematic fitting of hearing-aids and cochlear-implants, potentially improving clinical outcomes in noisy environments. Existing SIMs are suitable for predicting performance of normal-hearing subjects, but not for hearing-impaired subjects due to our limited understanding of the effects of cochlear hearing impairment on speech-in-noise coding. In this work, we collected auditory-nerve (AN) single-unit responses and envelope following responses (EFR) in normal- and hearing-impaired chinchillas to speech, spectrally-matched stationary-noise, and noisy-speech. Our data show increased correlation between AN-fiber response envelopes of noisy-speech and noise-alone for hearing-impaired fibers in speech-relevant modulation-frequency bands, suggesting a greater degree of distraction from inherent envelope fluctuations following cochlear hearing loss. This novel finding is significant given the emphasis recent SIMs [e.g., Jorgensen and Dau, JASA (2011)] have pla...