First of all, have you checked that your machines are well oiled? My sister's was much, much quieter when I got her to oil it. Second, instead of buying a new machine, consider getting a 'white noise' generator for your husband. Until I moved my sewing room downstairs, I sewed in the room next to my parents since I had to be upstairs during the day to look after my Dad. My mom is a very light sleeper and the machine never bothered her once I got her a nature sounds generator. Here's a
cheap one.
This is the one I bought, but I don't recommend it because a lot of people apparently are unable to figure out how to use it (I bought it for parents 8 years ago).