A hearing aid is a wearable sound-amplifying “medical device” that is intended to compensate for impaired hearing. Hearing Aids can be programmed and custom fitted to the specific hearing loss of an individual based on their hearing test and must be dispensed by a licensed hearing instrument specialist or a certified audiologist.
In contrast, a personal sound amplifier is a wearable “electronic product” that is not intended to compensate for impaired hearing even though the internal components are virtually identical to a hearing aid. Amplifiers do not need to be dispensed by a licensed specialist.
This is a distinction made by the FDA’s desire to regulate one but not the other.
Medical devices must be FDA approved and annually registered.
An hearing aid amplifier also known as a PSAP does not require FDA approval HOWEVER I am not aware of any manufacturer of sound amplifiers that have not had their product FDA approved. This includes Amazon’s best selling personal sound amplifier, the Otofonix Elite, which is FDA Registered in the United States.