TY - JOUR
T1 - Group delay of acoustic emissions in the ear
AU - Ren, Tianying
AU - He, Wenxuan
AU - Scott, Matthews
AU - Nuttall, Alfred L.
PY - 2006/11
Y1 - 2006/11
N2 - It is commonly accepted that the cochlea emits sound by a backward traveling wave along the cochlear partition. This belief is mainly based on an observation that the group delay of the otoacoustic emission measured in the ear canal is twice as long as the forward delay. In this study, the otoacoustic emission was measured in the gerbil under anesthesia not only in the ear canal but also at the stapes, eliminating measurement errors arising from unknown external- and middle-ear delays. The emission group delay measured at the stapes was compared with the group delay of basilar membrane vibration at the putative emission-generation site, the forward delay. The results show that the total intracochlear delay of the emission is equal to or smaller than the forward delay. For emissions with an f2/f1 ratio <1.2, the data indicate that the reverse propagation of the emission from its generation site to the stapes is much faster than a forward traveling wave to the f2 location. In addition, that the round-trip delays are smaller than the forward delay implies a basal shift of the emission generation site, likely explained by the basal shift of primary-tone response peaks with increasing intensity. However, for emissions with an f1 ≪ f2, the data cannot distinguish backward traveling waves from compression waves because of a very small f1 delay at the f2 site.
AB - It is commonly accepted that the cochlea emits sound by a backward traveling wave along the cochlear partition. This belief is mainly based on an observation that the group delay of the otoacoustic emission measured in the ear canal is twice as long as the forward delay. In this study, the otoacoustic emission was measured in the gerbil under anesthesia not only in the ear canal but also at the stapes, eliminating measurement errors arising from unknown external- and middle-ear delays. The emission group delay measured at the stapes was compared with the group delay of basilar membrane vibration at the putative emission-generation site, the forward delay. The results show that the total intracochlear delay of the emission is equal to or smaller than the forward delay. For emissions with an f2/f1 ratio <1.2, the data indicate that the reverse propagation of the emission from its generation site to the stapes is much faster than a forward traveling wave to the f2 location. In addition, that the round-trip delays are smaller than the forward delay implies a basal shift of the emission generation site, likely explained by the basal shift of primary-tone response peaks with increasing intensity. However, for emissions with an f1 ≪ f2, the data cannot distinguish backward traveling waves from compression waves because of a very small f1 delay at the f2 site.
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U2 - 10.1152/jn.00374.2006
DO - 10.1152/jn.00374.2006
M3 - Article
C2 - 16899644
AN - SCOPUS:33751202108
SN - 0022-3077
VL - 96
SP - 2785
EP - 2791
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 5
ER -