From American Suppressor Association:

The American Suppressor Association (ASA) is pleased to announce the introduction of the Hearing Protection Act (HPA) by Rep. Matt Salmon (AZ-05). This historic piece of legislation will remove suppressors from the purview of the National Firearms Act (NFA), replacing the antiquated federal transfer process with an instantaneous NICS background check. The HPA also includes a provision to refund the $200 transfer tax to applicants who purchase a suppressor after October 22, 2015.