This is precisely why no one uses the raw waveform. Speech recognizers and phoneticians alike use something which looks more like this: http://commons.wikimedia.org/wiki/File:Spectrogram_-iua-.png Speech recognition uses a couple more fancy transforms, plus the derivatives, but you get the idea.

And the claim that it can't be right because computers are discrete is just ludicruous. Neuron firing patterns are just as discrete as bits in a computer; and at the higher level, it doesn't matter much if you're looking at (continuous) firing rates or (continuous) floating-point numbers.