Very high pitch noise while broadcasting

[scratchermatch]

Whenever I broadcast, I will get the song just fine, but I also get a very high pitch sound in the background that really hurts my ears.
I can mitigate the problem by broadcasting at really low frequencies, but it's still there, faintly audible, and killing my ears.

Am I missing something stupid? How could I get rid of the noise?
I sped each of my audio clips up to x2 speed so that they played normally, which I hear increases the pitch, but even the slow one had the high pitch noise in the background.

[profiluefter]

I have the same problem but only after already playing something a few times. After a reboot it works again. The issue also exists in PiFmAdv and if one doesn't work anymore the other does not work too.
I'm using the shell at the moment but when I used the program a few months ago it worked flawlessly on the desktop terminal of the pi desktop.

[evertverduin]

This relates to my problem as well! The pitch you hear is the undersampled 19khz pilot ( outputing at 9.5 khz ).