Question
Are occupational noise-induced hearing losses always bilateral and symmetrical?
Answer
Typically, work-related noise-induced hearing loss is a bilateral, symmetrical sensorineural hearing loss with a notch at 3 kHz, 4 kHz or 6 kHz. There are some data indicating that 6kHz notches are more common than 4kHz notches in these hearing losses, especially in women.
There are some exceptions where asymmetrical occupational-related hearing loss may occur. Aside from acoustic trauma to one ear, causes may include a poorly fitting earplug/hearing protection device in one ear, employees who remove the hearing protection device in one ear (such as to use the telephone), or an employee who uses a loud two-way radio in one ear, for example. In addition to following your standard protocol for asymmetrical hearing losses, it is helpful to try and identify these causes or others that contribute to occupationally-related asymmetric hearing loss in order to prevent further progression.
This Ask the Expert question was based on information in the recorded course, "Investigating Work-Related Hearing Shifts".
Laurie Wells is a board-certified audiologist and Manager of Audiology for Associates in Acoustics, Inc. She received her Master's degree from University of Arizona and her clinical doctorate degree from Pennsylvania College of Optometry, School of Audiology. Laurie is a certified Professional Supervisor of the Audiometric Component of a Hearing Conservation Program. As a consultant to companies nationwide, she provides professional audiology review of hearing conservation programs to ensure effective protection from noise hazards to both employers and employees. This includes audiometric database analysis, assessment of hearing protection devices, and employee/employer education, worker's compensation reviews, and employee noise exposure assessment for both hearing conservation and regulatory compliance. Laurie represents the American Academy of Audiology on the Council for Accreditation in Occupational Hearing Conservation (CAOHC), and is an active CAOHC Course Director. She has taught numerous seminars, graduate audiology courses, and made frequent presentations at state and national conferences. Laurie is past-president of the National Hearing Conservation Association (NHCA), and served on the NHCA board from 1999 - 2006.