Hearing experiments

Introduction to deafness

Deafness - either total or partial - is a significant health issue today. A major source of this problem is due to loud sound. The likelihood of going deaf due to loud sound is increasing because of occupational and recreational sources of loud sound.

Now you may think deafness isn't that problematic. One of the major problems with deafness is social isolation. You stop attending parties or going out because understanding people, especially in even moderately noisy environments, becomes a problem. Something you have to strain at. And that's demanding – it makes you tired even after only a few minutes. There are also all the other problems – you mishear what the service attendant says you owe, and find you've underpaid – oh the embarrassment of it. Or even worse, when you think someone said something rather different from what they actually did and you respond in an inappropriate way...

Let me remind you of the statement of Helen Keller, who was both deaf and blind:

"Blindness separates people from things; deafness separates people from people."

So look after your hearing – it can only get worse from birth.

Loud sounds damage our hearing sensitivity

Exposure to loud noise also reduces our hearing sensitivity, again especially at higher frequencies. It does so in the same way as ageing does – by affecting the hair cells or the nerve fibres of the cochlea. So the general pattern of hearing loss due to loud sound is very similar to that of ageing – hearing loss is greatest at higher frequencies.

The effects of loud sounds depends both on the loudness of the sound and the duration for which you are exposed to it. In this simulation you will see these two effects in measurements of hearing levels, in males, as a function of their work environment (which works as an index for noise levels) and then as a function of duration of exposure to loud noise at work.

Again this is data collected from a large population of males in the 1980s, and things certainly haven't got any better since then – only worse because of much more recreational exposure to loud noise. In fact, in most developed countries, work places are now tightly regulated by noise abatement regulations (though you'll still see people not wearing hearing protectors!), and it's exposure to noise in recreational settings (night clubs, concerts, use of loud volumes in in-the-ear speakers) that is a major cause of hearing loss.

Effect of loud sounds on hearing sensitivity

Click on the items in the legend to view them on the graph.

Effect of loud sounds on hearing