Noise-Induced Damage to the Ear Is More Dangerous Than Assumed

Working or living in noisy environments is considered a normal part of our daily lives. Every day people on busy roads and often get stuck in traffic jams with blaring horns all around them. Many work environments are considered dangerously noisy – the modern office is sometimes no different from a busy market. Noise is not limited to industrial or outdoor sites only. Exposure to hazardous levels of sound can occur in the privacy of one’s bedroom too. Consider the common music player or a TV set that is capable of producing media at a high volume. All of these factors may lead to noise-induced damage to hearing.

In many cases, overexposure to intense sound causes temporary hearing loss. For example, have you had the chance to visit a musical concert and be seated very close to the gigantic loudspeakers? If so, you would remember that you weren’t able to hear things properly after walking out of the concert, and there was a ringing in your ears. Luckily, after a few hours of rest, you were able to hear normally again and apparently, the temporary hearing loss was reversed.

Dangerous Long-Term Effects of Noise-Induced Hearing Loss

It was always previously assumed that if threshold sensitivity is recovered after an episode of noise exposure, then the temporary hearing loss is completely reversed and no other damage is done to the ears. In most post-exposure tests, threshold sensitivity is considered the most important factor in ensuring the reversal of damage to the delicate mechano-sensory and neural structures of the inner ear.  It was believed that no other persistent or delayed consequences for auditory functioning remained.

However, a research published in The Journal of Neuroscience proves with the help of cochlear functional assays and confocal imaging of the inner ear in mice that acoustic overexposure may have long-term damaging effects and degeneration in the ear. It shows that while temporary hearing loss leaves cochlear sensory cells intact, it can cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve, leading to serious long-term effects.

This research provides a ground-breaking basis to question the earlier techniques used to measure noise-induced damage. The researchers believe that noise-induced damage to the ear has progressive consequences that are substantially more prevalent than are publicized by conventional threshold testing. They believe that even though temporary hearing loss may seem to be reversible, the primary neurodegeneration caused by overexposure to noise will prove to be harmful later on in life. It will add to difficulty people have in hearing in noisy environments, such as a meeting or a shopping center.

It may also contribute to tinnitus, a condition accompanying hearing loss that is characterized by a ringing in the ears. The research claims that it could also lead to hyperacusis and other perceptual irregularities commonly associated with inner ear damage. Therefore, it can be safely said that noise-induced hearing loss is more dangerous than previously thought.