[pantelisk]

it might be your speakers. Speakers are't neutral, they are optimized for a specific frequency response. Which means that the loudness might be "dropping significantly" rather than you not being able to listen to a specific frequency. Use pro headphones to properly test your hearing :)

(that's also why expensive studio monitors cost so much - the "this song sounds good on any type of speakers, from in ear-headphones, to cheap car radio speakers, to pro headphones to on cheap television", master once listen/play everywhere, used to be a big problem in the audio world. (it might still be, but I left that world -- consider the cheap car radio speakers as the Internet Explorer 6 of the audio world and you get the idea!)