Noise is the most common hazardous factor in industrial processes. For HSE specialists, this is a well-known fact. Any production facility and most processes are often filled with noise levels that exceed limits, even if only slightly. The maximum permissible level is 80 dB. Anything above this level, with constant exposure, can eventually lead to an occupational disease: sensorineural hearing loss.
Unfortunately, we often lack the necessary information to consciously protect our hearing from damage, sometimes exacerbating the issue in our daily lives. Many of us now use headphones, listening to loud music almost constantly. According to medical professionals, in the last century, this occupational disease was typically found only in older employees who had worked in noisy environments for many years. Today, the disease has become significantly 'younger' and is increasingly occurring in young people.
How does this disease develop?
Sounds are acoustic vibrations transmitted through the air. These vibrations, or sound waves, are captured by our outer ear. They cause the eardrum to vibrate. The latter sets in motion a chain of auditory ossicles connected to our inner ear. The inner ear's vestibule is a snail-shaped cavity filled with fluid. Mechanical vibrations of the fluid are converted into electrical impulses by tiny, sensitive hair cells. These impulses are transmitted to the brain via the auditory nerve. The brain receives them and forms sound images. So, what is an auditory injury? If the sound level exceeds permissible limits, the fluid pressure on the tiny hair cells increases sharply, leading to their damage. And damaged hair cells never recover. Therefore, if no measures are taken to protect your hearing, this negative process will progress, and hearing will gradually decline. Once total deafness occurs, no medications or surgeries can help. Even hearing aids are powerless. Sensorineural hearing loss is permanent.
What exactly is the three decibel rule? Sound pressure, which occurs when a sound wave passes through a medium, is calculated in decibels. This takes into account sound intensity — the energy carried by a sound wave through a medium per unit of time. The subjective characteristic of sound – loudness depends on sound intensity.
When sound intensity (loudness) doubles, it corresponds to a 3 dB increase on a logarithmic scale. For example: if we have a machine with a maximum permissible noise level of 80 dB and we place an identical machine with the same noise level next to it, the noise level at that workstation does not become 160 dB (which would be a lethal noise level), but 83 dB on the logarithmic scale. To put it even more simply, every 3 dB increase leads to a doubling of sound intensity or acoustic power. That is the three decibel rule. Can you imagine? A seemingly small increase in decibels leads to a massive change in sound intensity.
Here are the basic rules when working with decibels:
With this information, we can make a conscious decision to protect our hearing as carefully as we protect our eyes, for example. This means using hearing protection where technical measures cannot reduce noise levels. And, of course, not accelerating the onset of hearing loss in our daily lives. Every day, we should make the right choice in favor of preserving our health and quality of life.
During HSE training, I tell my colleagues about the three decibel rule, and you know, once they process this information, they start to view noise as a hazard differently. This is a simple path to conscious safety. Forewarned is forearmed.