How Much Do High Frequencies Matter In Practice? 2019-02-02 17:10:44 Lossy codecs such as Lame and FhG AAC cut high frequency content (>15-17 KHz) when encoding at moderate bitrates. I'm 34 and can easily hear pure, near-full-scale tones at 17 KHz and normal listening volumes, so I had always assumed that this filtering was a major source of any audible artifacts at these bitrates. I decided to test this hypothesis.To my surprise, I could not ABX the original FLAC of a song with lots of cymbals and distorted guitars against either a FLAC filtered at 15.6 KHz or a 128 kbps FhG AAC, which cuts at about this frequency. I therefore tried to create an even more-sensitive test to determine whether I might plausibly be able to hear the difference if I listened carefully enough for the right artifacts.I took the original FLAC and highpass filtered it at 15.6 KHz to hear only the sounds that would normally be filtered out, without masking from lower frequencies. At normal listening volumes, it sounds like complete silence to me. I don't think I'd be able to easily ABX it from complete silence without listening at volumes that would be unpleasantly loud on normal music. My conclusion is that on most real world music at real world listening volumes, a 15.6 KHz lowpass filter is very unlikely to be audible because high-frequency content in real music is both much lower amplitude and much broader spectrum than pure tones.I've attached short samples of the original song ("Westbound Sign" by Green Day) and the highpass filtered version for your entertainment.