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Normative Reflectance and Transmittance Measurements on Healthy Newborn and 1-Month-Old Infants

Merchant, Gabrielle R.1; Horton, Nicholas J.2; Voss, Susan E.3

doi: 10.1097/AUD.0b013e3181e68e68
Research Articles

Objective: Ear-canal-based wideband reflectance (WBR) measurements may provide objective measures to assess and monitor middle-ear status in young babies. This work presents WBR measurements of power reflectance and transmittance on populations of healthy newborn babies (3 to 5 days) and healthy 1-mo-old babies (28 to 34 days). Thus, this work determines how power reflectance and transmittance vary between newborn and 1-mo-old babies and characterizes the range of these measures in normal populations.

Design: Power reflectance and transmittance were calculated from pressure measurements made in the ear canals of seven newborn (12 ears) and eleven 1-mo-old (19 ears) babies. Permutation tests, t tests, and regression (random effects) models were used to test the effects of age (newborn versus 1 mo), gender, and ear side (right versus left).

Results: The power reflectance and transmittance did not differ significantly for the age comparison (newborn versus 1 mo), although the results suggest a possible difference between newborn and 1-mo-old ears near 2000 Hz. There were no differences between the male and female ears. There are small but significant differences between left and right ears in three frequency bands encompassing 500 to 4000 Hz, where the predicted power reflectance mean for the left ear differs from the right ear by 0.02 to −0.07 depending on the frequency band.

Conclusions: At most frequencies, power reflectance and transmittance are indistinguishable for newborn and 1-mo-old healthy babies, with limited or no differences between the two age groups and the males and females. There were small differences in some frequency bands for left and right ears. The measurements made here are similar to other published results in some frequency ranges but differ in other frequency ranges; differences among other studies from neonatal intensive care unit babies, healthy newborn babies, and healthy 1-mo-old babies are discussed.

Wide-band reflectance measures provide a potential mechanism for the detection of middle ear fluid in young ears. Herein, power reflectance and transmittance measurements are reported from healthy newborn and 1-mo-old babies. At most frequencies, power reflectance and transmittance are indistinguishable for newborn and 1-mo-old healthy babies, with limited or no differences between the two age groups and the males and females. There were small differences in some frequency bands for left and right ears. The measurements made here are similar to other published results in some frequency ranges but differ in other frequency ranges; differences among other studies from neonatal intensive care unit babies, healthy newborn babies, and healthy 1-mo-old babies are discussed.

1Smith College; 2Department of Mathematics and Statistics, and 3Picker Engineering Program, Smith College, Northampton, Massachusetts.

This work was supported by grant CBET-0642600 from the National Science Foundation.

Presented at the 2009 American Auditory Society annual meeting.

This work was the undergraduate honors thesis of Gabrielle R. Merchant under the direction of Susan E. Voss and Nicholas J. Horton.

Address for correspondence: Susan E. Voss, Picker Engineering Program, Smith College, Ford Hall, 100 Green Street, Northampton, MA 01063. E-mail: svoss@smith.edu.

Received July 31, 2009; accepted April 28, 2010.

© 2010 Lippincott Williams & Wilkins, Inc.