When trying to fully understand the difference between analog and digital hearing aids, you need to first appreciate the history of analog vs digital, and the different ways that they amplify and process sounds. Analog hearing aids appeared first, and were the standard in the majority of hearing aids for a long time. Subsequently, with the introduction of digital signal processing (DSP) technology, digital hearing aids also began to appear. Most (up to 90%) hearing aids purchased in the United States at this point are digital, although you can still find analog hearing aids because some people have a preference for them, and they are often cheaper.
Analog hearing aids handle inbound sounds by taking the electrical sound waves as they leave a microphone and amplifying them "as is" before sending them to the speakers in your ears. Digital hearing aids take the sound waves from the microphone and convert them to digital binary code, the "bits and bytes" and "zeros and ones" that all digital devices understand. This digital information can then be manipulated in many complex ways by the micro-chip within the hearing aid, prior to being converted back into ordinary analog signals and sent to the speakers.
Analog and digital hearing aids carry out the same work – they take sounds and boost them to allow you to hear better. Both analog and digital hearing aids can be programmable, meaning that they contain microchips which can be modified to adjust sound quality to suit the individual user, and to create various settings for different listening environments. The programmable hearing aids can, for instance, have one particular setting for use in quiet rooms, another for listening in noisy restaurants, and still another setting for listening in large stadiums.
Digital hearing aids, due to their capacity to manipulate the sounds in digital form, generally offer more features and flexibility, and are commonly user-configurable. For example, digital hearing aids may offer numerous channels and memories, permitting them to store more location-specific profiles. They can also employ advanced rules to identify and reduce background noise, to remove feedback and whistling, or to selectively prefer the sound of human voices and "follow" them using directional microphones.
Cost-wise, most analog hearing aids are still less expensive than digital hearing aids, but some reduced-feature digital hearing aids are now in a similar general price range. There is commonly a perceivable difference in sound quality, but the question of whether analog or digital is "better" is entirely up to the individual, and the ways that they are used .