In March 2009, the FDA issued guidance describing how hearing aids and personal sound amplifying devices differ.
This guidance defines a hearing aid as a sound-amplifying device intended to compensate for impaired hearing.

PSAPs are not intended to make up for impaired hearing. Instead, they are intended for non-hearing-impaired consumers to amplify sounds in the environment for a number of reasons, such as for recreational activities.

The FDA recommends: "If you suspect hearing loss, get your hearing evaluated by a health care professional,"

Read more from the FDA here