"which they do not perceive" is key here. I suspect that HN readers tend to an above-average degree of sensory sensitivity that causes them to notice things mos

"which they do not perceive" is key here. I suspect that HN readers tend to an above-average degree of sensory sensitivity that causes them to notice things most people don't. Add to that even a little training/experience in audio and the noises that drive you crazy are likely completely inaudible to others.