I started learning piano not so long ago and there is something that's confusing me a lot: when I play some notes at the same time (chords or two notes) sometimes I hear a second higher vibrating sound besides the notes I play. It depends on which notes, for example I can hear it very clearly when I play G#3 and C4 in my digital piano. I've been researching and I suppose this might come from the overtones or maybe from the acoustic beats that they might produce.
I'm pretty sure this is not a problem with my keyboard since I hear this everywhere I play these two notes.
I uploaded a recording of these two notes being played together in some random website where I can clearly hear what I'm saying: https://on.soundcloud.com/rvJT6
So my question is: Is this normal? Does everyone hear this? I get very distracted by this while playing, could it be that they bother me more than to other people? When I play the Fm chord for example I hear this very loud
EDIT: I was just playing around with audacity and the same audio file that I shared and I found out that if I equalize it muting the 1000 Hz frequency I stop hearing the sound I mention, just and only that frequency (I suppose it's a range). If I make it louder I hear the thing louder of course and if I only play that frequency alone, then I still hear it.
So what I'm thinking is that this is a beat caused by the 4th harmonic of C4 (1046.502 Hz) and the 5th harmonic of G#3 (1038.262 Hz)