Does it ring a bell?

This article is written in collaboration with the Week of Sound.

Most of people have experienced a high pitched noise after being exposed to loud sounds such as a music concert, heavy traffic or a stadium atmosphere. It usually subsides after a while, and is a naturally occurring phenomenon. Yet, some people hear such sounds even unprovoked, and they can range from barely audible to distracting. If this rings any bells, it might be high time to see a doctor!

Tinnitus affects 10-15% of people around the world, and becomes more prevalent with increased age. One in every three people over the age of 55 is affected by it, with their conditions ranging from mild to severe.
It is most often perceived as a ringing sound without any external source. It can be perceived in one or both ears, or more central in the head. Other than ringing, it can take the form of buzzing, whining, hissing, tinging, clicking, roaring, ticking, beeping or a myriad of other sounds, including a pure steady tone.

Rather than a disease, it is a symptom that results from various underlying causes, including hearing damage, noise-induced or age-related hearing loss, ear infections, tumors of the auditory nerves of the inner ear, migraines, head injuries, accumulated earwax and other.

Acute tinnitus

The most prevalent form of tinnitus is the acute version, which starts as a reaction to an outside event. Most commonly experienced example is the ringing in ears after attending a loud music concert, being exposed to loud traffic or fireworks. This happens because sound waves travel through the ear canal to the middle and inner ear, where hair cells in part of the cochlea help transform those sound waves into electrical signals that then travel to the brain's auditory cortex via the auditory nerve. When hair cells are damaged, the circuits in the brain don't receive the signals they're expecting. This stimulates abnormal activity in the neurons, which results in the illusion of sound. Other examples of acute tinnitus include accumulation of earwax which interferes with sound pathways, infections and certain ototoxic medications, where tinnitus subsides upon removal of the underlying problem, or shortly thereafter. One definition of tinnitus, as compared to normal ear noise experience, is noise lasting five minutes at least twice a week. It can be present constantly or intermittently, with some people not being aware of it all the time, but only for example during the night when there is less environmental noise to mask it.

Picture 1: illustration of ear and auditory pathways to the brain. Hair cells in the cochlea help transform the audio waves into electric signals which travels via the auditory nerve to the brain. Disruption of this pathway may lead to acute tinnitus, whereas damaging the pathway may lead to a chronic version.

Chronic tinnitus

If the sounds persist for six months or more, we are talking about chronic tinnitus. The causes are similar to acute tinnitus, but more severe. It usually involves damage to the inner ear, or more directly to the hair cells of the cochlea. Untreated tinnitus often worsens with age and damage accumulation, and can become so prominent that it affects everyday activities, levels of concentration, sleep, and others. While there is no cure for tinnitus, it can be lessened by understanding and treating the underlying problem.

Objective tinnitus

Tinnitus is subjective in vast majority of cases, meaning, it is a sound only the affected person can perceive. But a minority of cases experience objective tinnitus, where it can be detected by other people and is sometimes caused by muscle twitches, jaw clicking, dislocation of small bones around the ear area, or even altered blood flow, called pulsatile tinnitus. This type of tinnitus results from increased blood turbulence near the inner ear such as from atherosclerosis or venous hum. Rarely, pulsatile tinnitus may be a symptom of potentially life-threatening conditions such as carotid artery aneurysm or carotid artery dissection. Pulsatile tinnitus may also indicate vasculitis, or more specifically, giant cell arteritis and should be accounted for when diagnosing.

Treatment

There is currently no cure for tinnitus, although patient aren't left to their own devices. No single approach works for everyone, and some combining of treatments might be necessary to find the best approach.

Cognitive behavioral therapy focuses on making the sound less bothersome and noticeable, if not more silent. This can significantly improve the quality of life in patients with severe conditions.

Tinnitus Retraining Therapy aims to habituate the auditory system to the tinnitus signals, making them less noticeable or bothersome. Their assumption is that tinnitus results from abnormal neuron activity caused by a disruption or damage in the auditory pathway. It uses sound therapy to generate low-level noise and environmental sounds that match the pitch, volume and quality of patient's tinnitus, shadowing it.

Masking the tinnitus signal is another way to lessen the persistent pestering of tinnitus sounds, especially during sleeping hours. Wearable or tabletop sound generators are used for this purpose. They can produce sounds ranging from soft hush, to random tones, soft music, sounds of rain, waterfalls or waves, leaves rustling or similar.

Having a persistent sound bothering every minute of your life can become annoying, agitating or even distracting in a dangerous sense. Tinnitus might not be life-threatening per se, but neglection and misinformation can lead to unnecessary complications and decreased quality of life, stress, and in the worst cases depression and sleep disorders. While no medication have been approved for its treatment yet, there are promising alternatives currently being investigated, such as Repetitive Transcranial Magnetic Stimulations, Deep Brain Stimulations, and stimulation of the inner ear, with emphasis on the cochlea.

References:

1. Han BI, Lee HW, Kim TY, Lim JS, Shin KS (March 2009). "Tinnitus: characteristics, causes, mechanisms, and treatments". Journal of Clinical Neurology. 5 (1): 11–19. doi:10.3988/jcn.2009.5.1.11. PMC 2686891.

2. Langguth, B; Kreuzer, PM; Kleinjung, T; De Ridder, D (September 2013). "Tinnitus: causes and clinical management". The Lancet Neurology. 12 (9): 920–30. doi:10.1016/S1474-4422(13)70160-1. PMID 23948178. S2CID 13402806.

3. Levine, RA; Oron, Y (2015). "Tinnitus". The Human Auditory System – Fundamental Organization and Clinical Disorders. Handbook of Clinical Neurology. 129. pp. 409–31. doi:10.1016/B978-0-444-62630-1.00023-8. ISBN 9780444626301. PMID 25726282.

4. https://www.mayoclinic.org/diseases-conditions/tinnitus/symptoms-causes/syc-20350156

5. https://www.health.harvard.edu/diseases-and-conditions/tinnitus-ringing-in-the-ears-and-what-to-do-about-it

6. https://www.nidcd.nih.gov/health/tinnitus

7. https://www.ata.org/understanding-facts