TY - JOUR
T1 - Theory of forward and reverse middle-ear transmission applied to otoacoustic emissions in infant and adult ears
AU - Keefe, Douglas H.
AU - Abdala, Carolina
N1 - Funding Information:
This research was supported by the NIH (NIDCD Grant Nos. DC003784, DC003552, and DC006607), and the House Ear Institute. The authors would like to thank Dr. Ellen Ma and Sandy Oba for collection of infant data. The lead programmer in implementing the reflectance software at BTNRH was Dr. Denis F. Fitzpatrick.
PY - 2007
Y1 - 2007
N2 - The purpose of this study is to understand why otoacoustic emission (OAE) levels are higher in normal-hearing human infants relative to adults. In a previous study, distortion product (DP) OAE input/output (I/O) functions were shown to differ at f2 =6 kHz in adults compared to infants through 6 months of age. These DPOAE I/O functions were used to noninvasively assess immaturities in forward/reverse transmission through the ear canal and middle ear [Abdala, C., and Keefe, D. H., (2006). J. Acoust Soc. Am. 120, 3832-3842]. In the present study, ear-canal reflectance and DPOAEs measured in the same ears were analyzed using a scattering-matrix model of forward and reverse transmission in the ear canal, middle ear, and cochlea. Reflectance measurements were sensitive to frequency-dependent effects of ear-canal and middle-ear transmission that differed across OAE type and subject age. Results indicated that DPOAE levels were larger in infants mainly because the reverse middle-ear transmittance level varied with ear-canal area, which differed by more than a factor of 7 between term infants and adults. The forward middle-ear transmittance level was -16 dB less in infants, so that the conductive efficiency was poorer in infants than adults.
AB - The purpose of this study is to understand why otoacoustic emission (OAE) levels are higher in normal-hearing human infants relative to adults. In a previous study, distortion product (DP) OAE input/output (I/O) functions were shown to differ at f2 =6 kHz in adults compared to infants through 6 months of age. These DPOAE I/O functions were used to noninvasively assess immaturities in forward/reverse transmission through the ear canal and middle ear [Abdala, C., and Keefe, D. H., (2006). J. Acoust Soc. Am. 120, 3832-3842]. In the present study, ear-canal reflectance and DPOAEs measured in the same ears were analyzed using a scattering-matrix model of forward and reverse transmission in the ear canal, middle ear, and cochlea. Reflectance measurements were sensitive to frequency-dependent effects of ear-canal and middle-ear transmission that differed across OAE type and subject age. Results indicated that DPOAE levels were larger in infants mainly because the reverse middle-ear transmittance level varied with ear-canal area, which differed by more than a factor of 7 between term infants and adults. The forward middle-ear transmittance level was -16 dB less in infants, so that the conductive efficiency was poorer in infants than adults.
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U2 - 10.1121/1.2427128
DO - 10.1121/1.2427128
M3 - Article
C2 - 17348521
AN - SCOPUS:33846653131
SN - 0001-4966
VL - 121
SP - 978
EP - 993
JO - Journal of the Acoustical Society of America
JF - Journal of the Acoustical Society of America
IS - 2
ER -