Activation of medial olivocochlear efferents through contralateral acoustic stimulation ͑CAS͒ has been shown to modulate distortion product otoacoustic emission ͑DPOAE͒ level in various ways ͑enhancement, reduction, or no change͒. The goal of this study was to investigate the effect of a range of CAS levels on DPOAE fine structure. The 2f 1 -f 2 DPOAE was recorded ͑f 2 / f 1 = 1.22, L 1 = 55 dB, and L 2 =40 dB͒ from eight normal-hearing subjects, using both a frequency-sweep paradigm and a fixed frequency paradigm. Contamination due to the middle ear muscle reflex was avoided by monitoring the magnitude and phase of a probe in the test ear and by monitoring DPOAE stimulus levels throughout testing. Results show modulations in both level and frequency of DPOAE fine structure patterns. Frequency shifts observed at DPOAE level minima could explain reports of enhancement in DPOAE level due to efferent activation. CAS affected the magnitude and phase of the DPOAE component from the characteristic frequency region to a greater extent than the component from the overlap region between the stimulus tones. This differential effect explains the occasional enhancement observed in DPOAE level as well as the frequency shift in fine structure patterns.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.