Motorcycling is noisy business (wind, not exhaust), so I need to wear earplugs under the helmet.
I have a Bluetooth based comms system in the helmet. When I crank it up maximum volume, it is almost loud enough, at least at low speeds.
I can buy reusable earplugs with speakers in them, but I can only find wired ones.
The space available is limited. The device can not protrude from the ear, as it would interfere with the helmet. The outer ear cavity could be used, though.
I am thinking it might be possible to make a reusable earplug with the speaker in the ear canal and a coil (or other energy receiver) in the outer ear, and then replace the speakers in the helmet with another coil or other transducer. Is it as simple as a coil on each side?
The distance is small, and the amount of power required is also small.
Ideas?