Prior to the mid-1990s, all hearing aids were analogue. What that means is that hearing aids had a microphone, amplifier and a receiver just like the old rotary dial telephones every house used to have. Today hearing aids are digital. Microphones still receive the sound just as they always have but before they get to the amplifier, they go through digital conversion then manipulation. It is in this place before the amplifier, that the hearing aid filters the noise, the speech and the input signal for loudness levels and determines what needs to come out through the amplifier in order help you hear speech clearly in every listening situation. Digital hearing aids have gone from processing these sounds from milli-seconds to nano-seconds – this means it is a 1,000 times faster today than just a few years ago.
Today, digital hearing aid technology has the ability to hear and filter multiple noises simultaneously, adjust them independently, look at the speech, clarify the speech from multiple directions and put it through the amplifier at your optimal hearing levels to give you the clarity of understanding without lifting a finger. This all gets done at rates above 10 million sounds per second.
While you can still buy analogue hearing aids starting at $280 per aid, why would you?