Contralateral acoustic stimulation alters the magnitude and phase of distortion product otoacoustic emissions

• Published in: The Journal of the Acoustical Society of America Vol. 126; no. 5; pp. 2413 - 2424
• Main Authors: Deeter, Ryan, Abel, Rebekah, Calandruccio, Lauren, Dhar, Sumitrajit
• Format: Journal Article
• Language: English
• Published: Melville, NY Acoustical Society of America 01.11.2009; American Institute of Physics
• Subjects: Acoustic Stimulation - methods; Audition; Auditory Pathways - physiology; Auditory Threshold - physiology; Biological and medical sciences; Cochlea - physiology; Cochlear Nucleus - physiology; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Humans; Noise; Olivary Nucleus - physiology; Otoacoustic Emissions, Spontaneous - physiology; Perception; Physiological Acoustics; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Young Adult; Auditory disorder; Acoustics; Otoacoustic emission; Phase distortion
• ISSN: 0001-4966; 1520-8524; 1520-8524
• DOI: 10.1121/1.3224716

Activation of medial olivocochlear efferents through contralateral acoustic stimulation (CAS) has been shown to modulate distortion product otoacoustic emission (DPOAE) level in various ways (enhancement, reduction, or no change). The goal of this study was to investigate the effect of a range of CAS levels on DPOAE fine structure. The 2 f 1 - f 2 DPOAE was recorded ( f 2 / f 1 = 1.22 , L 1 = 55   dB , and L 2 = 40   dB ) 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.