Harry:
This problem can be one problem such as the origination point has low audio quality or the programs are being sent over two satellite hops and the 2nd uplink station maybe causing the low audio.
This can also be several little problems like your receive antenna being mis-aimed or not optimized for the desired satellite carrier, local interference such as trees to your receive antenna, or your IRD, or something else between your IRD and TV set.
I suggest start by ensuring your antenna system and equipment is workly correctly. Verify that your antenna is aimed correctly and optimized for best Eb/No (C/No) and/or Signal Strength. One of the better ways to do this is use a spectrum analyzer and peek the signal on the desired carrier. Try substituting another IRD and/or TV set in the current setup to see if that improves things.
That would some of the basics. I not sure if you have any technical experience so I am not going to go into more specifics for you may not understand it. Let me know if you or if someone else you know has experience in this field and I can provide more if the above does not resolve the situation.