Removing background vocals

[tempestuousfury]

I apologize if this is an easy question/ answered elsewhere, but the sticky did not really seem to answer this.

At any rate, I have attached the ~30 second song as an attachment. The issue is simply that the first 5 seconds has a background "aaah" (sorry, not musically inclined), that I wanted to remove. I tried the FFT filter and the inversion trick (karaoke or what have you), and of course neither worked. I'm sure it's a rather easy solution, but it required a post from me.

Thanks for any help provided.

[kozikowski]

The vocal, instruments and backup chorus are all heavily processed and echoed -- and they're all permanent parts of the show.

Koz