We got some ear defenders for use when operating the chain saw, here modelled by Mrs B's koala bear.
They came with a leaflet outlining their performance. I was interested that it is broken down by frequency. The table uses the word "attenuation". This means the reduction in the amplitude of a wave. Decibels is a logarithmic scale. The way it works is that if you ADD 10dB, you MULTIPLY the power output by 10. Logarithmic scales are non-linear so if you remove 3dB, you halve the power output. Now this doesn't necessarily mean that you have the perceived volume because of the way in which ears work. I have read that to halve perceived volume, you need to lose 10dB. I know from experiments that I have conducted that 4000 Hz is the most sensitive frequency for my ear. Notice that the attenuation is greatest at this end of the spectrum. Bearing in mind what I've read, I think that at that end of the spectrum, the volume might be 10% of normal. I need to think of a way to test it (and then actually try it!)
