The processing power of digital hearing aids allows much greater flexibility than analog devices. Digital hearing aids are “smarter” than analog, in that the microprocessors are able to interpret the incoming sound waves with greater accuracy.
Instead of applying the same amplification process to all incoming sound, digital hearing aids are able to selectively amplify some noises, while ignoring or even quieting others. By interpreting the consistency of the intensity of each individual sound, a digital processor can select those sounds that need to be amplified. Digital sound processing also produces a crisper, clearer sound than analog does, in much the same way that a compact disc sounds better than an audio cassette.
Digital hearing aids are also capable of managing feedback – the whistling noise caused by the microphones picking up the output from the speakers. As digital aids are capable of distinguishing different sounds, the frequency range in which the feedback is occurring can be slightly muted, reducing the whistling while still amplifying necessary speech sounds.
Directional microphones are employed in some analog and digital hearing aids. Unlike omnidirectional microphones which pick up sound in all directions, directional microphones only pick up the sound coming from the front, and reduce the sound coming from the rear (usually background noise). As digital hearing aids have exponentially more processing power, they are able to adapt to the input from the directional microphones more efficiently, making the directional microphone that much more effective.