Spontaneous otoacoustic emissions align with peaks in stimulus-frequency fine structure

Evidence

Stimulus frequency OAEs (SFOAEs), which are evoked using a single frequency sound, are one of the most diagnostic OAEs regarding cochlear function. They show a highly replicable individualistic pattern of amplitude maxima and minima when measured with high enough frequency resolution, a pattern called SFOAE fine structure. The level difference between maxima and minima can be as large as 30 dB. Usually SOAEs occur near the maxima of SFOAEs fine structure (Bergevin et al. 2012 ; Dewey and Dhar 2014 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 5757

An impressive effect, leading to the same conclusion, is the strong relation between the spectral composition of the emissions and the fine structure of the threshold measured in quiet as a function of frequency. When threshold in quiet is measured very carefully, i.e. not with continuously changing frequency but measuring point by point with a frequency distance between the points of only 2 or 3 Hz, many subjects show distinct maxima and minima. The same subjects usually show also many large emissions. … The pronounced minima of threshold in quiet (panel (d)) show a perfect correlation with the maxima in the spectral composition of delayed evoked emissions (panel (c)). This means that threshold in quiet shows lower values (the hearing system is more sensitive) if the spectrum of the evoked emission has a maximum. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 310

SOAEs usually occur near maxima of SFOAEs fine structure (Bergevin et al. 2012 ; Dewey and Dhar 2014 ), but SOAEs are not always detectable at such maxima. Thus, we decided also to measure SFOAE fine structure and select frequencies at the maxima and minima of the fine structure for the behavioural level discrimination task. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5763

SOAE frequencies were identified as a very narrow peak of energy at least 3 dB above an average of the background level of adjacent frequencies. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5763

Categorization

• DEFINE: Defines the SFOAE fine structure pattern of amplitude maxima and minima.
• XREF: The 30 dB amplitude variation in cochlear mechanics connects to the ‘threshold microstructure’ and loudness literature.
• SEED: An essay angle: the ear’s own emitted sounds mark its most sensitive frequencies — a kind of active resonance where the cochlea ‘shows’ where it hears best.
• SHARE: For an audiologist or hearing researcher: fine-structured threshold-in-quiet, measured at 2-3 Hz resolution, hides maxima/minima that align with emission spectrum peaks.
• corroborated: 4 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 5757; Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 310; Dijk, Pim van, Physiology, Psychoacoustics and…, 5763