Regulated devices have very specific definitions like is represented as O, or does x or z and a and b, or x and b. Things like that. The definition typically hinges on very specific parameters and ALSO what it is called. That way no one can sell an inert plug as a “hearing aid”, and no one can sell a hearing aids as “conversation enhancing devices “ to evade certification requirements if they meet the bar feature-wise to be a hearing aid.