Notched Pattern of Hearing Loss Not All From Leisure Noise Damage

(2018, Mar 2) had some alarming stats. Based on notched audiograms (one or both ears), 24% of non-occupational hearing loss in Americans is extrapolated to be from noise. This is an overestimate. Because audiometric notches, often called noise notches, can also be from age-related and genetic hearing loss. Evidence-based science shows you can’t blame all hearing tests with audiometric notches on noise. Unilateral hearing loss is never from noise. Only some asymmetrical audiograms might be from noise. Clark (2000) wrote an essay titled: Five Myths in Assessing the Effects of Noise on Hearing. He explains these and another important myth versus evidence-based science.

Myth: A notch at 4 kHz is called a ”noise notch” and it means that the hearing loss was caused or contributed to by noise exposure.

Evidence Based Science: The term “noise notch” implies causation; whereas “4 kHz notch” describes the audiometric pattern, and is therefore more descriptive and more accurate.

Myth: Asymmetric hearing losses are caused by asymmetric exposures.

Evidence Based Science:
A. The limit of asymmetric hearing losses from impulsive exposures is 5-10 dB in the lower frequencies, and about 20-25 dB in the high frequencies [e.g. recreational gunfire].

B. For continuous exposures, one should not expect any asymmetry at all, even though the offending noise originates from one side of the individual [even if directly beside one ear]

C. If asymmetries exceed these values, a medical referral is indicated.

Myth: All loud leisure noise is dangerous noise.

Evidence Based Science: Fact. All loud leisure noise is dangerous noise.

9 years after Clark’s essay, in 2009, evidence-based scientists proved that unprotected exposure to loud noise during work or leisure time causes HHL hidden hearing loss or cochlear synaptology. There are no symptoms at first. After the loud exposure, connections between the inner ear hearing hair cells and hearing nerve start to break and die off. Hearing nerve fibres rip and fray. It’s progressive.

The first symptom is hearing system distortion. Music and words won’t sound as clear. It gets hard to understand people when there’s background noise going on. Even though your hearing might still test as normal. If you notice temporary muffled hearing, tinnitus or hyperacusis that happens after loud leisure noise, progressive HHL is left behind. Distortion for music and speech. Eventually there’s enough damage that permanent sensorineural NIHL Noise-Induced HL shows up. There’s no treatment. Just hearing aids. If you don’t get hearing aids, unaided HL causes dementia. This is the latest science on HHL:

Guo, D. & Kujawa, S.G. (2018, March 1). What’s hidden in hidden hearing loss? ENT & Audiology News. Retrieved from https://www.entandaudiologynews.com/features/audiology-features/post/what-s-hidden-in-hidden-hearing-loss

CDC is absolutely right on everything else, especially the urgent need for global prevention efforts. A recent article in The Guardian – International Edition shares ample evidence there is too much damaging noise hurting the hearing, mental and physical health of the general public of all ages from newborns to seniors. Something has to be done. The cost of noise control and prevention will be far less than the billions needed to keep our healthcare systems afloat if the noise damage cases keep happening.

Photo Credit Chad Kirchoff at Unsplash

Jan’s Book Portfolio

Jan L. Mayes MSc writes horror fiction and non-fiction, and is an international Eric Hoffer Award winning author, blogger and audiologist specializing in ghosts, noise, tinnitus-hyperacusis, hearing health education and plotting murders. Her writing has been featured at Tinnitus Today, Communique, silencity.com and The Horror News Daily.