MOCR gain reduction masks true cochlear suppression and underestimates it

Evidence

Both younger and older adults in the present study showed significantly more suppression measured with short combined maskers than with longer combined maskers. Several of the older participants, who had no measurable suppression with the longer combined masker, had a small amount of suppression measured with the shorter combined masker. When suppression is measured with combined maskers long enough to elicit MOCR-induced gain reduction, suppression may be underestimated. However, even when measured with the shorter combined maskers, older adults had less suppression than younger adults. Evidence from animal studies suggests that gain reduction from the MOCR and suppression interact, resulting in decreased suppression (Winslow and Sachs 1987 ; Kawase et al. 1993 ). The results of the present study support this idea. — Dijk, Pim van, Physiology, Psychoacoustics and…, 962

Categorization

Category: Causal Relationships

• QUESTION: If MOCR-induced gain reduction interacts with suppression to reduce measured suppression, what does that imply for measuring suppression in hearing-impaired ears where MOCR is often impaired too? The confound may run in either direction.
• DEFINE: Defines MOCR (medial olivocochlear reflex) as a slow gain-reduction mechanism that interferes with suppression measurement when maskers are too long.

Related

• Long combined maskers trigger MOCR gain reduction that underestimates true suppression (similarity 0.95)
• Measured suppression is underestimated when maskers trigger medial-olivocochlear gain reduction (similarity 0.93)
• MOCR gain reduction interacts with suppression to reduce it (similarity 0.91)
• Suppression is underestimated by maskers long enough to trigger the MOCR (similarity 0.90)
• Masker duration gates whether the medial olivocochlear reflex contributes to measured gain (similarity 0.89)
• Masker durations over 25 ms trigger efferent feedback that reduces measured suppression (similarity 0.88)
• Suppressor duration windows distinguish MOCR-mediated gain from cochlear mechanics. (similarity 0.88)
• Sound durations longer than 25 ms recruit efferent feedback that reduces measured suppression (similarity 0.87)
• Prior suppression studies may be confounded because long stimuli trigger the medial olivocochlear reflex (similarity 0.86)
• Older adults show reduced cochlear two-tone suppression (similarity 0.86)
• Basilar membrane suppression can be altered by the sluggish medial olivocochlear reflex (similarity 0.85)
• Long suppressor durations elicit MOCR and may underestimate suppression (similarity 0.85)
• Medial olivocochlear reflex suppression requires maskers longer than 20 ms (similarity 0.84)
• Short maskers yield significantly larger suppression estimates than long ones (similarity 0.83)
• Older adults lose measurable suppression entirely when maskers are long (similarity 0.83)