When I fitted mine there were a couple of EBA retrofit guides floating around and I remember reading that if you get the pins wrong or something or other with the jumper plug you won't get sound.

Some sites say you need to remove the wheel sensor pins 7 (yellow with green tracer) and 8 (white with green tracer) from the ULF plug and run a separate voice jumper plug. I established that this was for US spec cars which already have BMW® assist voice recognition fitted to them them as standard. Therefore I didn't have to do this and I would suggest that you only have to do this if you have a US spec car. In my case the pins weren't in the ULF plug to remove and the voice jumper plug wasn't required. If the plug was required you'd have no audio output and if you didn't remove the pins your speedo and odometer wouldn't work.

See if page 18 helps you here http://www.wardphotography.com/e46toronto/BTBMWInstall.pdf