Jake woke up on Thanksgiving morning and noticed a ringing in his ears. He was in middle school. What he did not know at the time was that the ringing would not go away. Through high school, college, and now working as an engineer, the ringing never stopped. Jake was unwittingly joining an estimated 40 to 50 million Americans with tinnitus. Jake’s tinnitus is of the annoyance variety; nothing he would choose but a condition he can live with and manage. For others, a constant ringing, buzzing, or clicking can be debilitating.
Tinnitus refers to an auditory perception that is not produced by an external sound. By definition, tinnitus is the sensation of hearing a “hissing, roaring, or ringing” in the ears and can range from high pitch to low pitch, consist of multiple tones, or sound like noise (having no tonal quality at all). The noise is usually constant, but can also be perceived as pulsed or intermittent noise. Tinnitus may begin suddenly or develop gradually. Sensorineural hearing loss is a common cause of tinnitus. Other known causes include middle ear obstructions, head and neck trauma, temporomandibular joint disorder, sinus pressure, barometric trauma (diving/flying), traumatic brain injury, ototoxic drugs, ototoxic chemicals, hypothyroidism, hyperthyroidism, anemia, Lyme disease, fibromyalgia, Ménière’s disease, high blood pressure, depression, anxiety, and stress.
My interest in tinnitus is its connection to occupationally-induced hearing loss. Experts disagree on the relationship between tinnitus and hearing loss:
“Although tinnitus is often associated with hearing loss, it does not cause the loss, nor does a hearing loss cause tinnitus.”(WebMD, Understanding Tinnitus – the Basics)
“Sensorineural hearing loss is a common cause of tinnitus. Some researchers believe that subjective tinnitus cannot exist without some prior loss of hearing.” (American Tinnitus Association (ATA))
“One of the preventable causes of tinnitus is excessive noise exposure.” (American Academy of Otolaryngology – Head and Neck Surgery, AAO-HNS)
“In some instances of noise exposure, tinnitus can be noticed even before hearing loss develops, so it should be considered a warning sign and an indication of the need for hearing protection in noisy environments.” (AAO-HNS)
Questions arise from the above contradictory statements from WebMD, ATA, and AAO-HNS.If you have tinnitus does that mean you also have hearing loss? If employees report tinnitus, can we assume they are heading towards hearing loss? Is tinnitus an early warning sign that could be used to prompt hearing conservation interventions?
The answer to these questions is “perhaps”. Not a satisfying answer, but medically, tinnitus is considered a symptom, not a disease. Just as headaches are symptoms for thousands of unrelated medical problems. Tinnitus is a symptom of underlying conditions. The sensorineural system that converts acoustical energy to electrical signals that are interpreted by our brains is for some unknown reason turned on in the absence of the physical input we call sound waves.
The wide variety of causes of tinnitus as well as the incomplete understanding of its complex physiological mechanisms make it too difficult to make the blanket statement that tinnitus is always a sign of impending hearing loss.
If we could definitively link tinnitus with hearing loss it might be easier for us to prevent further hearing damage. We need to keep in mind that hearing loss is irreversible – so the earlier we know about some level of hearing loss, the more effectively it can be addressed. However, hearing loss doesn’t typically occur with physical symptoms or warning signs. The social warnings (“Turn down that TV”) indicate that an individual has already lost some hearing function. The annual audiogram keeps score of what an individual has already lost.
Among the known causes of tinnitus, two have relevance to the workplace and are in our control: (1) noise, and (2) ototoxic chemicals. While I hesitatingly say that noise and ototoxic chemicals “cause” tinnitus, I can say with certainty that both noise and ototoxic chemicals1 may cause hearing loss. It might be useful to view tinnitus as a precursor for hearing loss; however, we do better by focusing on the cause of hearing loss rather than the symptoms. Sensorineural hearing loss is caused by exposure to noise. The good news is that we know how to evaluate and control noise exposures. Unfortunately, the evidence, both anecdotal and factual, suggests that as a whole we don’t do a good job preventing occupationally induced hearing loss. OSHA reports 125,000 workers with permanent hearing loss since 20042. NIOSH reports hearing loss accounted for 14% of occupational illness in 2007 3.
A section from chapter one of the AIHA Noise Manual “Brief Historical Overview and Perspective” 4 characterizes hearing conservation as unsuccessful. The authors cite a 1987 article which noted the lack of progress preventing hearing loss despite our know-how. The authors then make the comment that not much had improved between 1987 and the publishing of the fifth edition in 2000. Can we claim any success in the following fifteen years? How does your hearing conservation program stack up? Chances are if you’re just providing hearing protection and audiometric testing, your program is not as effective as it could be.
Jake’s tinnitus may or may not go away. He didn’t choose to get it and there is nothing he can do to get rid of it. What he can do is protect his hearing. We can hope he works for employers that value his health and well-being to include his hearing in the future.
4 The Noise Manual, Fifth Edition, 2000, American Industrial Hygiene Association, www.aiha.org.