Cochlear hearing loss raises interaural time discrimination thresholds independent of age

Evidence

Many studies of the effects of hearing loss on discrimination of interaural time differences (ITDs) are confounded by differences in age between the normal-hearing and hearing-impaired subjects. One exception is the study of Hawkins and Wightman ( 1980 ). They measured just noticeable differences in ITD using low-frequency (450–550 Hz) and high-frequency (3750–4250 Hz) narrow-band noise stimuli. The ITD was present in both TFSp and ENVp , except that the onsets and offsets of the stimuli were synchronous across the two ears. Performance was probably dominated by the use of TFS cues for the low frequency and ENV cues for the high frequency. They tested three normal-hearing subjects (mean age 25 years) and eight subjects with hearing loss (mean age 27 years). The two groups were tested both at the same sound pressure level (85 dB SPL) and at the same sensation level (30 dB SL). ITD thresholds were significantly higher for the hearing-impaired than for the normal-hearing subjects for both signals at both levels. These results suggest that cochlear hearing loss can adversely affect the discrimination of ITD carried both in TFSp and in ENVp . — Dijk, Pim van, Physiology, Psychoacoustics and…, 817

One exception is the study of Hawkins and Wightman ( 1980 ). They measured just noticeable differences in ITD using low-frequency (450–550 Hz) and high-frequency (3750–4250 Hz) narrow-band noise stimuli. The ITD was present in both TFSp and ENVp , except that the onsets and offsets of the stimuli were synchronous across the two ears. Performance was probably dominated by the use of TFS cues for the low frequency and ENV cues for the high frequency. They tested three normal-hearing subjects (mean age 25 years) and eight subjects with hearing loss (mean age 27 years). The two groups were tested both at the same sound pressure level (85 dB SPL) and at the same sensation level (30 dB SL). ITD thresholds were significantly higher for the hearing-impaired than for the normal-hearing subjects for both signals at both levels. These results suggest that cochlear hearing loss can adversely affect the discrimination of ITD carried both in TFSp and in ENVp . — Dijk, Pim van, Physiology, Psychoacoustics and…, 811

Categorization

• DEFINE: Useful distinction of TFSp vs ENVp cues split by stimulus frequency band.
• QUESTION: A rare study age-matched (25 vs 27) to isolate hearing loss from age for binaural TFS — why are so few others designed this way?
• corroborated: 4 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 817; Dijk, Pim van, Physiology, Psychoacoustics and…, 811
• XREF: connects to: Aging degrades envelope-based binaural phase discrimination independent of hearing loss — Dijk, Pim van, Physiology, Psychoacoustics and…, 809; Noise exposure and age produce distinct hearing-loss signatures; Interaural envelope timing responses weaken with rising carrier frequency and ear mismatch (+4 more)

Broader Connections

• Interaural envelope timing responses weaken with rising carrier frequency and ear mismatch #expands (0.85)
• Differential metrics can separate cochlear gain loss from temporal coding deficits in hearing loss #corroborates (0.80) — Dijk, Pim van, Physiology, Psychoacoustics and…, 5870
• Temporal-structure sensitivity declines with age even when audiograms remain normal. #qualifies (0.80) — Dijk, Pim van, Physiology, Psychoacoustics and…, 793
• Noise exposure and age produce distinct hearing-loss signatures #qualifies (0.75)
• Cochlear hearing loss spares the binaural processing of envelope cues #complicates (0.75) — Dijk, Pim van, Physiology, Psychoacoustics and…, 822