How does our hearing deteriorate?
Noise can cause permanent damage to the auditory system and is the most common occupational injury and disabling factor for hearing. In daily life, noise comes from many sources, such as transportation noise, industrial noise, noise from public events, and noise from military environments.
How does noise damage our hearing? And how does noise deafness occur?
Free radicals
Free radicals should be no stranger to everyone, especially women who love beauty. Free radicals can be called the "root of all evil" because they are our aging face's culprit.
Free radicals are a by-product of cellular activity, like a messy kitchen after a feast. Free radicals attack and destroy normal cells, a significant cause of human disease and accelerated aging.
If there are more free radicals in the skin cells, the skin will become dry and inelastic, and wrinkles and age spots will appear; if there are more free radicals in the blood vessels, atherosclerosis, hypertension, and cerebral hemorrhage will occur; if there are more free radicals in the organs, tumors and cancers will come out. Likewise, more free radicals in the cochlea can cause damage to the ear.
Studies have found that both reactive oxygen radicals and reactive nitrogen radicals in the cochlea increase after noise exposure. The rate at which these radicals are generated far exceeds the ability of the antioxidant enzyme system to remove them.
Simultaneously, noise stimulation also causes hypoxia and ischemia in the inner ear and a decrease in the activity of antioxidant enzymes and free radical scavengers, which in turn leads to an excessive accumulation of free radicals and damage to inner ear hair cells.
What damage can our hair cells suffer?
Studies have shown that noise exposure causes damage to the nucleus of cochlear hair cells and ssDNA production, which is an early manifestation of cell death.
Besides, mutations in mitochondrial DNA (mtDNA) can also be caused. When the accumulation of mutant mtDNA in the cell reaches a certain level, and the capacity generated by oxidative phosphorylation falls below the threshold for maintaining normal cellular function, the degeneration of tissues and organs begins.
Yes, that's right. This means that our "precious" "non-renewable" cochlear hair cells are dying one by one under the stimulation of noise.
When the number of dead hair cells reaches a certain level, we develop hearing loss. We can never hear sound in a particular frequency band.
Who kills the cochlear hair cells?
Interestingly, it is not the noise that kills our cochlear hair cells, but rather our cochlear hair cells that can't stand the noise and choose to "kill themselves."
There are two main types of cell death: a programmed death called apoptosis and a non-programmed death called necrosis.
Apoptosis occurs when cells actively activate their pre-set cellular self-destruction mechanisms under various damaging stimulus conditions and does not cause an inflammatory response in the surrounding tissues. In contrast, cell necrosis is a passive death process that occurs due to pathological reasons. Also, it tends to cause inflammatory reactions in the surrounding tissues, etc.
For the sake of understanding and differentiation, we can also consider apoptosis as a cellular "suicide" action and cell necrosis as "other killing."
Numerous experiments have confirmed that the primary mode of noise-induced hair cell death is apoptosis.
In other words, without our knowledge, our cochlear hair cells may have become unbearable and have quietly activated their self-destruct mechanism to destroy themselves.
So, many irreversible hearing losses occur more suddenly than one might think.
How can we protect our hearing in a noisy environment?
1. reduce contact time with noise, and be sure to isolate yourself from noise when resting.
2. People who work in a noisy environment for a long time should have regular hearing examinations to detect and treat the problem in time.
3. Those who have sensorineural deafness and noise sensitivity should avoid working in robust noise environments.
4. Actively take measures or control the sound source. You can adopt ear sound insulation for the noise that cannot be controlled, wear earplugs, earmuffs, soundproof caps, and other soundproof equipment.
5. Avoid prolonged use of "Walkman" and turn down the volume. High volume audio can cause fatigue and damage to the auditory organs, leading to hearing loss and even deafness.
6. If you find that you have difficulty hearing, please seek medical attention.