Abstract
Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds. SNHL-induced changes in the coding of amplitude-modulated sounds may have a detrimental effect on the ability of SNHL listeners to understand speech in the presence of modulated background noise. To date, direct evidence for a link between magnified envelope coding and deficits in speech identification in modulated noise has been absent. Here, magnetoencephalography was used to quantify the effects of SNHL on phase locking to the temporal envelope of modulated noise (envelope coding) in human auditory cortex. Our results show that SNHL enhances the amplitude of envelope coding in posteromedial auditory cortex, whereas it enhances the fidelity of envelope coding in posteromedial and posterolateral auditory cortex. This dissociation was more evident in the right hemisphere, demonstrating functional lateralization in enhanced envelope coding in SNHL listeners. However, enhanced envelope coding was not perceptually beneficial. Our results also show that both hearing thresholds and, to a lesser extent, magnified cortical envelope coding in left posteromedial auditory cortex predict speech identification in modulated background noise. We propose a framework in which magnified envelope coding in posteromedial auditory cortex disrupts the segregation of speech from background noise, leading to deficits in speech perception in modulated background noise.
| Original language | English |
|---|---|
| Pages (from-to) | 7727-7736 |
| Number of pages | 10 |
| Journal | Journal of neuroscience |
| Volume | 37 |
| Issue number | 32 |
| Early online date | 10 Jul 2017 |
| DOIs | |
| Publication status | Published - 9 Aug 2017 |
Bibliographical note
Copyright © 2017 Millman et al. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.Keywords
- Acoustic Stimulation/methods
- Aged
- Audiometry, Speech/methods
- Auditory Cortex/physiology
- Auditory Perception/physiology
- Female
- Forecasting
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Sensorineural/physiopathology
- Humans
- Magnetoencephalography/methods
- Male
- Middle Aged
- Noise/adverse effects
- Perceptual Masking/physiology
- Speech Perception/physiology
