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larly true for thresholds at 6 and 8 kHz which are much more variable than ones for frequencies between 0.5 kHz and 4 kHz when measured using supraaural earphones, the type used in the NHANES study. This problem of high variability with supraaural earphones is exacerbated at 6 kHz because of a cali- bration error that makes thresholds about 5 dB poorer at this frequency than those at adjacent frequencies in young persons with no history of ear disease and or noise exposure (Lutman and Qasem, 1998). This calibration error makes it much more likely a false-positive HFN will be observed and, consequently, increases the chance of observing a false high frequency hear- ing loss. Using Shargorodsky’s criteria for a high-frequency hearing loss, we found the same high prevalence for hearing loss in a group of 6-8 year olds in the NHANES 1988-1994 data that Shargorodsky et al. reported for teens in their study. Children who are 6-8 years old are at a low risk for NIHL.
Conclusions
Our studies (Schlauch and Carney 2011, 2012) demonstrate that the percentage of children with NIHL is much lower than suggested by some other analyses of the NAHNES data. Pure tone audiometry is the gold standard for quantifying a hearing loss, but it is limited in its precision when identifying a small change in hearing or a mild hearing loss caused by incipient NIHL. The diagnosis of incipient NIHL can be improved by making multiple measurements of thresholds and averaging (Schlauch and Carney 2011, 2012; Jin et al., 2013) and by com- pleting a complete diagnostic audiometric exam, which includes an assessment of middle-ear function, otoscopy, and bone-con- duction thresholds. Bone-conduction thresholds were not measured as part of the NHANES protocol.
There is some evidence (Schlauch and Carney, 2007) that insert earphones may produce less variable (more precise) high- frequency thresholds than the supraaural earphones required by OSHA for industrial hearing monitoring. Insert earphones can also be calibrated in the ear canal using a probe-tube micro- phone to correct for deviations of the targeted SPL at the eardrum in individual ears (see Scheperle, Goodman & Neely, 2011). It is also important to have accurate baseline thresholds and complete personal history information (Jin et al., 2013).
Finally, the absence of evidence of widespread hearing loss
in teens does not mean children are not at risk for NIHL. Kujawa and Liberman (2009) have reported extensive damage to the cochlea following noise exposure that is not measurable using pure-tone thresholds. The hearing loss may appear years after the damage to the cochlea occurred. Youth should be taught about the risks that intense sounds pose to hearing and about the use of hearing protection devices.AT
References
Jin, S., Nelson, P.B., Schlauch, R.S. and Carney E. (2013). “Hearing con- servation program for marching band members: risk for noise- induced hearing loss?,” American Journal of Audiology 22, 26-39.
Kujawa, S. G., and Liberman, M. C. (2009). “Adding insult to injury: cochlear nerve degeneration after “temporary” noise-induced hear- ing loss,” Journal of Neuroscience 29, 14077-14085.
Lutman, M. E. and Qasem, H. Y. N. (1998). “A source for notches at 6.0 kHz. In Advances in Noise Research: Biological Effects of Noise”, Vol. I (Edited by D. Prasher & L. Luxon). (Whurr Publishers Ltd., London), pp 170-176
Niskar, A. S., Kieszak, S. M., Holmes, A. E., Esteban, E., Rubin, C., and Brody, D. J. (2001). “Estimated prevalence of noise-induced hearing threshold shifts among children 6 to 19 years of age: The third national health and nutrition examination survey, 1988-1994, United States,” Pediatrics108, 40-43.
Occupational Safety and Health Administration. (1983). Occupational noise exposure: hearing conservation amendment. Occupational Safety and Health Administration, 29 CFR 1910.95; 48 Federal Register, 9738–9785.
Scheperle A., Goodman S.S., and Neely S. (2011). “Further assessment of forward pressure level for in situ calibration,” Journal of the Acoustal Society of America 130, 3882-3892.
Schlauch R.S., and Carney E. (2007). “A multinomial model for identi- fying significant pure-tone threshold shifts,” Journal of Speech, Language, and Hearing Research 150, 1391–1403.
Schlauch R.S., and Carney E. (2011). “Are false-positive rates leading to an overestimation of noise-induced hearing loss?,” Journal of Speech, Language and Hearing Research 54, 679-692.
Schlauch R.S., and Carney E. (2012). “The challenge of detecting min- imal hearing loss in audiometric surveys,” American Journal of Audiology 21, 106-119.
Shargorodsky, J., Curhan, S., Curhan, G., and Eavey, R. (2010). “Change in prevalence of hearing loss in US adolescents,” Journal of the American Medical Association 304, 772-778.
Robert Schlauch is a professor in the Department of Speech- Language-Hearing Sciences at the University of Minnesota where he joined the faculty in 1989. His research interests include intensity perception (psychoacoustics), cognitive factors influencing hear- ing, and diagnostic audiology. He is a Fellow of the Acoustical Society of America and of the American Speech Language Hearing Association.
18 Acoustics Today, October 2013