Low-frequency stimulation can reveal latent otoacoustic emissions invisible before exposure

Evidence

17 of 21 tested subjects revealed an overall of 56 new SOAEs, which had not been measurable before LF stimulation (see Fig. 2b ). These new SOAEs were characterized by an initial level and frequency increase, qualitatively similar to the pre-existing SOAEs. Comparable to the enhancing half cycle of Bouncing SOAEs, their level and frequency oscillated before they disappeared into the noise floor. The duration of the level and frequency changes was 67.5 s (47.5 s, 90 s). New SOAEs started to arise within 12.5 s (5 s, 25 s) after LF sound offset and reached a level maximum at 50 s (35 s, 62.5 s) after LF offset. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3719

Categorization

• QUESTION: What biophysical state does an SOAE occupy when it is unmeasurable pre-exposure yet emerges under LF stimulation? Does this imply SOAEs are always present but vary in the strength of their coupling to the ear canal?