Degraded interaural timing coding, not audiometric asymmetry, explains reduced MLD in hearing loss.

Evidence

The size of the MLD typically decreases as the severity of hearing loss increases, as well as with asymmetric hearing losses. That is, listeners with more severe hearing losses receive less of a binaural release from masking by presenting a signal (but not a noise) in antiphase across the ears. Even small asymmetries across the ears can reduce the size of the MLD. Yet, small differences in hearing levels between the ears cannot fully account for the reductions in the size of the MLD (Hall, Tyler, & Fernandes, 1984; Quaranta & Cervellera, 1974). The poor coding of interaural timing cues in these listeners provides a better explanation for the reduced MLD associated with SNHL. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1590

A number of studies have demonstrated that the masking level difference is reduced in listeners with sensorineural hearing loss (Durlach et al., 1981). The size of the MLD typically decreases as the severity of hearing loss increases, as well as with asymmetric hearing losses. That is, listeners with more severe hearing losses receive less of a binaural release from masking by presenting a signal (but not a noise) in antiphase across the ears. Even small asymmetries across the ears can reduce the size of the MLD. Yet, small differences in hearing levels between the ears cannot fully account for the reductions in the size of the MLD (Hall, Tyler, & Fernandes, 1984; Quaranta & Cervellera, 1974). The poor coding of interaural timing cues in these listeners provides a better explanation for the reduced MLD associated with SNHL. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1590

Categorization

• QUESTION: Why would interaural timing coding be the dominant driver of MLD reduction when level differences between ears contribute? Worth chasing how ITD coding degrades in SNHL mechanistically.
• DEFINE: Clarifies that MLD is a binaural release from masking, and distinguishes the audiometric-asymmetry explanation from the interaural-timing explanation.
• XREF: Ties the binaural mechanism material of this chapter to the reader’s broader question of how normal vs impaired hearing differ causally.
• corroborated: 2 independent passages support this claim — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1590