The filter bands they're talking about are Bark bands (https://en.wikipedia.org/wiki/Bark_scale https://en.wikipedia.org/wiki/Bark_scale) and are actually repre

The filter bands they're talking about are Bark bands (https://en.wikipedia.org/wiki/Bark_scale https://en.wikipedia.org/wiki/Bark_scale) and are actually representative of the way the ear perceives loudness. In a traditional hearing aid, you might have a compressor for each of these Bark bands to counteract the effects of loudness recruitment (http://www.sens.com/helps/helps_d03.htm http://www.sens.com/helps/helps_d03.htm).