[48ford]

A place I worked at installed a 6" steam jet to produce vacuumed. We received noise complaints from folks 2 miles away. Our plant engineer had us build a muffler for it.
The muffler was nothing more than a section of 12" pipe with a roll of chicken wire fencing inside it. The center of the muffler was totally open because he wanted no back pressure to hurt the effienceny of the steam jet. The muffler was very quiet and after 6 years of operation it was still working. I think you could do the same with a side pipe. If the tips were tacked in place you could experiment to get the sound level you want very easily and inexpensive to try.