Requirements for music player/headphones and speaker?

[Vetoed]

I just bought a pair of earphones. The package claims that it has a frequency response (or whatever it's called) of 20Hz - 20kHz, which should have fit the bill. But I did the audio test, and I kept hearing barely audible pulsing sounds after 15 seconds in. Is it just me, or is the manufacturer lying.......It's annoying how it's so hard to find the right earphones that are reasonably cheap so that I can use them for Hybrid subs.

It only cost me 15USD btw.