Spontaneous basilar membrane oscillation and otoacoustic emission at 15 kHz in a guinea pig.
A spontaneous otoacoustic emission (SOAE) measured in the ear canal of a guinea pig was found to have a counterpart in spontaneous mechanical vibration of the basilar membrane (BM). A spontaneous 15-kHz BM velocity signal was measured from the 18-kHz tonotopic location and had a level close to that evoked by a 14-kHz, 15-dB SPL tone given to the ear. Lower-frequency pure-tone acoustic excitation was found to reduce the spontaneous BM oscillation (SBMO) while higher-frequency sound could entrain the SBMO. Octave-band noise centered near the emission frequency showed an increased narrow-band response in that frequency range. Applied pulses of current enhanced or suppressed the oscillation, depending on polarity of the current. The compound action potential (CAP) audiogram demonstrated a frequency-specific loss at 8 and 12 kHz in this animal. We conclude that a relatively high-frequency spontaneous oscillation of 15 kHz originated near the 15-kHz tonotopic place and appeared at the measured BM location as a mechanical oscillation. The oscillation gave rise to a SOAE in the ear canal. Electric current can modulate level and frequency of the otoacoustic emission in a pattern similar to that for the observed mechanical oscillation of the BM.
Nuttall
A L
AL
Oregon Hearing Research Center, Department of Otolaryngology and Head & Neck Surgery, Oregon Health & Science University, Portland, OR 97239-3098, USA. nuttall@ohsu.edu
Grosh
K
K
Zheng
J
J
de Boer
E
E
Zou
Y
Y
Ren
T
T
D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001489:Basilar Membrane / Q000502:physiology*; D004424:Ear Canal; D004594:Electrophysiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D006168:Guinea Pigs; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*