Hey tom you might be interested to know that the muscles in your ears harden up when you talk so you don't hear yourself (they act as a damper to the leverage mechanism in your ear)  this leads to your understanding of the sound of your own voice being different to when you hear a recording - mostly you hear yourself through vibrations in your jawbone. So not only does speaking drown out the noise but it also just makes your hearing worse- and dampers are especially effective at high frequencies.