Analog hearing aids use a continuously varying electrical signal to produce sound. Digital hearing aids change the electrical impulses into binary code (zeroes and ones), and these numbers are analyzed by a microprocessor within the hearing aid. Using a set of algorithms, the microprocessors process the impulses, and transmit the energy to the speaker.
Analog hearing aids offer fewer options than digital, and must be adjusted by an audiologist in the office, though there are manual volume controls on some models. Analog hearing aids are the least flexible, but often the least expensive hearing aids available.