How Sensitive Are Our Ears to Noise At Work?
Posted in General on May 05, 2015
Your ears are amazing. That might sound like something that ranks fairly highly on a list of terrible pick-up lines, but people are often unaware of the incredible feats that their ears perform on a daily basis. In fact, your ears are more sensitive than the sound level meters we use to measure noise exposure in the workplace noise exposure in the workplace.
The fact that human hearing is so under-rated might stem from the frequent unfavourable comparisons it receives; we all know that a dog's hearing is much more sensitive than a human's for example (but did you know cats have better hearing than dogs?). Contrary to this perception, human hearing is actually incredibly sensitive and sophisticated.
Our dynamic range (the difference between the quietest and loudest sounds we can perceive) of 0 db – 130 dB may not sound like much, but because the decibel scale is logarithmic, our dynamic range actually covers a truly staggering 12 orders of magnitude. That's the difference between detecting vibrations at less than a billionth of an atmospheric pressure and the sound of a jet taking off. In fact, if our ears were any more sensitive we would be able to hear the motion of particles. Our ability to detect pitch is equally impressive; a human with perfect hearing can detect sounds in a frequency range of 20 Hz to 20,000 Hz. All this is accomplished by the basilar membrane, a part of our ears less than 2mm across.
That's not the only clever trick the human ear can perform. Our ears contain the smallest bones in our bodies, the hammer, anvil and stirrup. These bones work like a lever system, mechanically amplifying the energy of sounds we hear so our organ of hearing, the cochlea, can better decode them. That's pretty impressive, but our ears also modify the frequency content of sound we hear. Our ear canal is just the right size to resonate perfectly with frequencies between 2-4 kHz, the frequencies that are most important for understanding human speech. As if that wasn't enough, our brains are constantly analysing cues in the sound we hear about distance and direction to help us navigate the world around us. We do all of this without thinking about it, it comes to us as naturally as breathing.
In short, trust your ears, they're better than you think. If you think noise at work seems excessive, odds are that it probably is. Don't pretend you can't hear what your ears are telling you, get a second opinion from an acoustic consultant and their sound level meter.