Temporal Fine-Structure Coding and Lateralized Speech Perception in Normal-Hearing and Hearing-Impaired Listeners.
Gusztáv Lőcsei, Julie H Pedersen, Søren Laugesen and 3 others
PMID 27601071WHAT IT FOUND
Low-frequency timing cues did not explain hearing-impaired listeners' difficulty understanding speech when talkers were spatially separated.
Hearing-impaired older adults still needed louder speech than normal-hearing listeners, especially in fluctuating noise. Separating talkers helped all groups.
Key findings
01Hearing-impaired listeners needed more favorable signal-to-noise ratios than normal-hearing listeners, and the group gap increased as the masker became more fluctuating.
02Spatial separation of target and maskers improved speech reception thresholds in all groups, but the hearing-impaired groups gained about 1 dB less than normal-hearing listeners.
03Low-frequency timing measures did not predict speech perception in spatial listening; the apparent phase-discrimination effect disappeared after hearing thresholds were controlled.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study included 19 hearing-impaired and 10 normal-hearing listeners, so findings are limited by small group sizes. Frequency-discrimination data were missing for five hearing-impaired listeners because of time limitations. The normal-hearing group was young and the hearing-impaired group was elderly, so age and hearing loss were confounded in the main group comparison. The speech tests used headphones and artificial interaural time differences, so they may not match everyday rooms. Only timing at 250 Hz was measured, so broader frequency timing ability may have been missed. Attention was not measured, although the random left-right task may have made attention a limiting factor. The hearing-impaired group was split into mild and moderate high-frequency loss, and the unexpected worse timing in the mild subgroup may reflect how the groups were divided.
The easy way to misread this
Do not conclude that temporal fine-structure deficits cause hearing-impaired listeners' difficulty with spatial speech. The timing tests did not predict speech-in-noise performance after hearing thresholds were controlled, so this study does not show that these timing deficits are the cause of the speech difficulty.