Good points HB3. I don't have a sound meter or a chronograph.
I'm not sure that I can always tell by listening. Subtle differences in sound are hard to detect, especially if you are losing some of your hearing. I haven't checked into sound meters, but I would think they would be a good tool for this.
I work mine to what I can detect as a low noise spot, and consider that as a starting point. Then it might take me a month of adjusting and tweaking to get to what I will finally settle on as the best spot.