TY - JOUR
T1 - Influence of contralateral acoustic stimulation on distortion-product and spontaneous otoacoustic emissions in the barn owl
AU - Manley, Geoffrey A.
AU - Taschenberger, Grit
AU - Oeckinghaus, Horst
N1 - Funding Information:
The authors are grateful to Christine Köppl for helping perform the middle-ear surgery, for cementing the head-holder pins and for commenting on the manuscript. Supported by a Grant to GAM from the Deutsche Forschungsgemeinschaft within the program of the SFB 204 ’Gehör’.
PY - 1999/12
Y1 - 1999/12
N2 - The avian auditory papilla provides an interesting object on which to study efferent influences, because whereas a significant population of hair cells in birds is not afferently innervated, all hair cells are efferently innervated (Fischer, 1992, 1994a, b). Previous studies in mammals using contralateral sound to stimulate the efferent system demonstrated a general suppressive effect on spontaneous and click-evoked, as well as on distortion- product otoacoustic emissions (DPOAE). As little is known about the effects of contralateral stimulation on hearing in birds, we studied the effect of such stimuli (broadband noise, pure tones) on the amplitude of the DPOAE 2f1-f2 and on spontaneous otoacoustic emissions (SOAE) in the barn owl, Tyto alba. For the DPOAE measurements, fixed primary-tone pairs [f1 = 8.875 kHz (ratio = 1.2), f1 = 8.353 kHz (ratio = 1.15) and f1 = 7.889 kHz (ratio=1.1)] were presented and the DPOAE measured in the presence and absence of continuous contralateral stimulation. The DPOAE often declined in amplitude but in some cases we observed DPOAE enhancement. The changes in amplitude were as large as 9 dB. The influence of the contralateral noise changed over time, however, and the effects of contralateral tones were frequency-dependent. SOAE were suppressed in amplitude and shifted in frequency by contralateral broadband noise. Control measurements in animals after middle-ear muscle resection showed that these phenomena were not attributable to the acoustic middle-ear reflex. The finding of DPOAE enhancement is interesting, because a type of efferent fiber that suppressed its discharge rate during stimulation has been described in birds (Kaiser and Manley, 1994).
AB - The avian auditory papilla provides an interesting object on which to study efferent influences, because whereas a significant population of hair cells in birds is not afferently innervated, all hair cells are efferently innervated (Fischer, 1992, 1994a, b). Previous studies in mammals using contralateral sound to stimulate the efferent system demonstrated a general suppressive effect on spontaneous and click-evoked, as well as on distortion- product otoacoustic emissions (DPOAE). As little is known about the effects of contralateral stimulation on hearing in birds, we studied the effect of such stimuli (broadband noise, pure tones) on the amplitude of the DPOAE 2f1-f2 and on spontaneous otoacoustic emissions (SOAE) in the barn owl, Tyto alba. For the DPOAE measurements, fixed primary-tone pairs [f1 = 8.875 kHz (ratio = 1.2), f1 = 8.353 kHz (ratio = 1.15) and f1 = 7.889 kHz (ratio=1.1)] were presented and the DPOAE measured in the presence and absence of continuous contralateral stimulation. The DPOAE often declined in amplitude but in some cases we observed DPOAE enhancement. The changes in amplitude were as large as 9 dB. The influence of the contralateral noise changed over time, however, and the effects of contralateral tones were frequency-dependent. SOAE were suppressed in amplitude and shifted in frequency by contralateral broadband noise. Control measurements in animals after middle-ear muscle resection showed that these phenomena were not attributable to the acoustic middle-ear reflex. The finding of DPOAE enhancement is interesting, because a type of efferent fiber that suppressed its discharge rate during stimulation has been described in birds (Kaiser and Manley, 1994).
KW - Barn owl
KW - Bird
KW - Contralateral acoustic stimulation
KW - DPOAE
KW - Efferent system
KW - Otoacoustic emission
UR - http://www.scopus.com/inward/record.url?scp=0032753933&partnerID=8YFLogxK
U2 - 10.1016/S0378-5955(99)00126-4
DO - 10.1016/S0378-5955(99)00126-4
M3 - Article
C2 - 10575110
AN - SCOPUS:0032753933
SN - 0378-5955
VL - 138
SP - 1
EP - 12
JO - Hearing Research
JF - Hearing Research
IS - 1-2
ER -