Well I just made a reply but it I somehow got logged out and that post is gone :/
70db is still pretty loud, you can find compressors around 40db. (Search garage journal for dental compressor, you will find more than you want to know about quiet.) The quieter the compressor the more the price, you might just want to deal with the sound. You can buy or make silencers, and or relocate the compressor to and enclosed space to spare your ears. A shed or garage attic will do well, just add a remote drain and power switch. Keep in mind more efficient compressors will be on less, and you will have to listen to them less. Oiled compressors also tend to be rebuild-able while oil less are disposable most of the time.
If you don't need a lot of air and want to save money, you might look into using a fridge compressor. Listen to your fridge for an idea of how loud they are.