NIOSH has a ‘buy quiet’ campaign that promotes buying of quiet tools. Here is the link:

http://www.cdc.gov/niosh/topics/buyquiet/default.html

A great document they have (from New York) is a listing of tools AND the sound levels when in use.  In other words, if you purchase tools that produce less noise, your employees (or yourself, for that matter) is protected.  Here is that document:

Click link below for document:

Guide to Quiet tools – NIOSH New York