A hearing aid is an electronic device that amplifies and processes sound, and which is worn to compensate for a hearing loss. Hearing aids come in different shapes and sizes. However, they all work in a similar way by delivering amplified sound to the ear.
All conventional hearing aids have a microphone to pick up sound and convert it to an electrical signal. This signal is then processed by a series of electrical components in an analogue hearing aid, or by a tiny ‘computer’ in a digital hearing aid. Most hearing aids are now digital. Once processed, the signals are finally passed to a receiver (earphone), or to a small vibrator that is worn against the bones behind your ear. This converts the electrical signal back to sound - ideally at a level that you can hear and clearly understand.
A typical, modern "Behind the ear" style hearing aid with ear fitting (Image © RNID)