title: Influence of sound-conditioning on noise-induced susceptibility of distortion-product otoacoustic emissions.
abstract: Cochlear damage caused by loud sounds can be attenuated by "sound-conditioning" methods. The amount of adaptation for distortion product otoacoustic emissions (DPOAEs) measured in alert rabbits previously predicted an ear's susceptibility to a subsequent noise exposure. The present study investigated if sound-conditioning influenced the robustness of such DPOAE adaptation, and if such conditioning elicited more protection by increasing the amount of DPOAE adaptation. Toward this end, rabbits were divided into two study groups: (1) experimental animals exposed to a sound-conditioning protocol, and (2) unconditioned control animals. After base-line measures, all rabbits were exposed to an overstimulation paradigm consisting of an octave band noise, and then re-assessed 3 weeks post-exposure to determine permanent changes in DPOAEs. A major result was that prior sound-conditioning protected reductions in DPOAE levels by an average of 10-15 dB. However, DPOAE adaptation decreased with sound-conditioning, so that such conditioning was no longer related to noise-induced reductions in DPOAEs. Together, these findings suggest that sound-conditioning affected neural pathways other than those that likely mediate DPOAE adaptation (e.g., medial olivocochlear efferent and/or middle-ear muscle reflexes).
authors.affiliation: Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Luebke
authors.affiliation: Research Service, Veterans Affairs Loma Linda Healthcare System, Loma Linda, California 92357, USA.
authors.forename: Barden B
authors.initials: BB
authors.lastname: Stagner
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Loma Linda University Medical Center, Loma Linda, California 92354, USA.
authors.forename: Glen K
authors.initials: GK
authors.lastname: Martin
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Loma Linda University Medical Center, Loma Linda, California 92354, USA.
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Lonsbury-Martin
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D003051:Cochlea / Q000502:physiology; D003213:Conditioning, Psychological; D005260:Female; D008297:Male; D009622:Noise; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D010469:Perceptual Distortion / Q000502:physiology*; D010898:Pitch Perception / Q000502:physiology; D011817:Rabbits; D012022:Reflex, Acoustic / Q000502:physiology