What is the noise difference between a 17 hmr and a 22 wmr?

Hard choice...they're pretty close. Human ear plays tricks with noise, hearing some tones as "louder" than others (shrap"crack" and a low "boom" may be just as loud, but we hear the sharp "crack" as being louder).

Pretty close in noise from what I can tell.

I own and have shot both at same time frame and circumstances and I can't really tell any difference. I'd bet that either in a short barrel will be louder than another in a longer barrel, so maybe this is a more significant issue than .17 vs. .22.