system
Given the following post, respond as if you're commenting on Reddit:
human
When people are listening to loud music through headphones, why do other people only hear the drums/beat of the music?

This happens every day when I’m on the bus, and it just annoys me throughout that 30 minutes of my day. I just thought it was interesting that I only heard the beat of the music, and not the melody.
gpt
A lot of it has to do with the Fletcher-Munson curve and how we perceive sounds.  


Our ears are more-finely tuned to pick up midrange frequencies (400Hz-\~4kHz) and the quieter a source is, the more of those mid frequencies we hear over the lows and highs.  


Now the thing about drums is that we really don't hear the fundamental frequencies all that well (snare is down \~200Hz, kick drum is down \~60Hz), but we DO hear the harmonics really well since those are generally in the midrange.  In order to get those elements to sit better in a mix, we not only turn up those tracks, but we actually remove some of the mids in the melodic instruments (otherwise all of that midrange likes to build up and has a tendency of sounding like the song is in a cardboard box or through a telephone).  So, since our ears pick up the mids the best at lower volumes, the drums are brought up to sit better in the mix, and the mids of the melody instruments are pulled back a bit, at lower volumes, you're gonna hear the midrange of that snare (and the overhead mics picking up the cymbals) and not much else.  


source:  Audio Engineering student.