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Suppression tuning of spontaneous otoacoustic emissions in the barn owl (Tyto alba)

Engler, S., Köppl, C., Manley, G. A., de Kleine, E. & van Dijk, P., Jan-2020, In : Hearing Research. 385, 9 p., 107835.

Research output: Contribution to journalArticleAcademicpeer-review

Spontaneous otoacoustic emissions (SOAEs) have been observed in a variety of different vertebrates, including humans and barn owls (Tyro alba). The underlying mechanisms producing the SOAEs and the meaning of their characteristics regarding the frequency selectivity of an individual and species are, however, still under debate. In the present study, we measured SOAE spectra in lightly anesthetized barn owls and suppressed their amplitudes by presenting pure tones at different frequencies and sound levels. Suppression effects were quantified by deriving suppression tuning curves (STCs) with a criterion of 2 dB suppression. SOAEs were found in 100% of ears (n = 14), with an average of 12.7 SOAEs per ear. Across the whole SOAE frequency range of 3.4-10.2 kHz, the distances between neighboring SOAEs were relatively uniform, with a median distance of 430 Hz. The majority (87.6%) of SOAEs were recorded at frequencies that fall within the barn owl's auditory fovea (5-10 kHz). The STCs were V-shaped and sharply tuned, similar to STCs from humans and other species. Between 5 and 10 kHz, the median Q(10dB) value of STC was 4.87 and was thus lower than that of owl single-unit neural data. There was no evidence for secondary STC side lobes, as seen in humans. The best thresholds of the STCs varied from 7.0 to 57.5 dB SPL and correlated with SOAE level, such that smaller SOAEs tended to require a higher sound level to be suppressed. While similar, the frequency-threshold curves of auditory-nerve fibers and STCs of SOAEs differ in some respects in their tuning characteristics indicating that SOAE suppression tuning in the barn owl may not directly reflect neural tuning in primary auditory nerve fibers. (C) 2019 Elsevier B.V. All rights reserved.

Original languageEnglish
Article number107835
Number of pages9
JournalHearing Research
Volume385
Early online date1-Nov-2019
Publication statusPublished - Jan-2020

    Keywords

  • Auditory, Frequency selectivity, Spontaneous otoacoustic emission, Suppression, Barn owl, COCHLEAR NUCLEUS MAGNOCELLULARIS, BASILAR-MEMBRANE MOTION, AUDITORY-NERVE FIBERS, BOBTAIL LIZARD, COHERENT REFLECTION, DISTORTION-PRODUCT, GENERATION, MOTILITY, FEATURES, PAPILLA

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