TY - JOUR
T1 - Two-tone distortion at different longitudinal locations on the basilar membrane
AU - He, Wenxuan
AU - Nuttall, Alfred L.
AU - Ren, Tianying
N1 - Funding Information:
The authors are grateful to the two Hearing Research reviewers for helpful comments and suggestions on the manuscript, and to Edward Porsov and Scott Matthews for technical assistance and valuable discussions. This study was supported by Grants from National Institute on Deafness and Other Communication Disorders.
PY - 2007/6
Y1 - 2007/6
N2 - When listening to two tones at frequency f1 and f2 (f2 > f1), one can hear pitches not only at f1 and f2 but also at distortion frequencies f2 - f1, (n + 1)f1 - nf2, and (n + 1)f2 - nf1 (n = 1, 2, 3 ...). Such two-tone distortion products (DPs) also can be measured in the ear canal using a sensitive microphone. These ear-generated sounds are called otoacoustic emissions (OAEs). In spite of the common applications of OAEs, the mechanisms by which these emissions travel out of the cochlea remain unclear. In a recent study, the basilar membrane (BM) vibration at 2f1 - f2 was measured as a function of the longitudinal location, using a scanning laser interferometer. The data indicated a forward traveling wave and no measurable backward wave. However, this study had a relatively high noise floor and high stimulus intensity. In the current study, the noise floor of the BM measurement was significantly decreased by using reflective beads on the BM, and the vibration was measured at relatively low intensities at more than one longitudinal location. The results show that the DP phase at a basal location leads the phase at an apical location. The data indicate that the emission travels along the BM from base to apex as a forward traveling wave, and no backward traveling wave was detected under the current experimental conditions.
AB - When listening to two tones at frequency f1 and f2 (f2 > f1), one can hear pitches not only at f1 and f2 but also at distortion frequencies f2 - f1, (n + 1)f1 - nf2, and (n + 1)f2 - nf1 (n = 1, 2, 3 ...). Such two-tone distortion products (DPs) also can be measured in the ear canal using a sensitive microphone. These ear-generated sounds are called otoacoustic emissions (OAEs). In spite of the common applications of OAEs, the mechanisms by which these emissions travel out of the cochlea remain unclear. In a recent study, the basilar membrane (BM) vibration at 2f1 - f2 was measured as a function of the longitudinal location, using a scanning laser interferometer. The data indicated a forward traveling wave and no measurable backward wave. However, this study had a relatively high noise floor and high stimulus intensity. In the current study, the noise floor of the BM measurement was significantly decreased by using reflective beads on the BM, and the vibration was measured at relatively low intensities at more than one longitudinal location. The results show that the DP phase at a basal location leads the phase at an apical location. The data indicate that the emission travels along the BM from base to apex as a forward traveling wave, and no backward traveling wave was detected under the current experimental conditions.
KW - Basilar membrane
KW - Distortion products
KW - Laser interferometer
KW - Otoacoustic emission
KW - Traveling wave
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U2 - 10.1016/j.heares.2007.01.026
DO - 10.1016/j.heares.2007.01.026
M3 - Article
C2 - 17353104
AN - SCOPUS:34247465173
SN - 0378-5955
VL - 228
SP - 112
EP - 122
JO - Hearing Research
JF - Hearing Research
IS - 1-2
ER -