To understand the difference between analog and digital hearing aids, you need to first understand the history of analog vs digital, and the different ways that they process and amplify sounds. Historically, analog technology emerged first, and consequently most hearing aids were analog until digital signal processing (DSP) was invented, after which digital hearing aids appeared. The majority of (roughly 90%) hearing aids sold in the US at this point are digital, although you can still find analog hearing aids because some people have a preference for them, and they are typically less expensive.
The way that analog hearing aids work is that they take sound waves from the microphone in the form of electricity and then amplify the waves, sending louder versions of the sound waves to the speakers in your ears “as is.” In contrast, digital hearing aids utilize the very same sound waves from the microphone, but before amplifying them they turn the sound waves into the binary code of “bits and bytes” that all digital devices use. Once the sound has been digitized, the micro-chip inside the hearing aid can manipulate the information in sophisticated ways before transforming it back to analog sound and delivering it to the ears.
It is important to remember that analog and digital hearing aids have the same function – they take sounds and boost them so that you can hear them better. Both analog and digital hearing aids can be programmable, meaning that they contain microchips that can be modified to adjust sound quality to match the individual user, and to develop various configurations for different listening environments. For example, there can be different settings for low-noise rooms like libraries, for busy restaurants, and for large areas such as sports stadiums.
Digital hearing aids, because of their ability to manipulate the sounds in digital form, generally offer more features and flexibility, and are commonly user-configurable. They have multiple memories in which to store more environment-specific configurations than analog hearing aids. Other features of digital hearing aids include the ability to automatically minimize background noise and remove feedback or whistling, or the ability to prefer the sound of voices over other sounds.
Price-wise, most analog hearing aids continue to be less expensive than digital hearing aids, but some reduced-feature digital hearing aids fall into the same general price range. There is commonly a perceivable difference in sound quality, but the question of whether analog or digital is “better” is up to the individual, and the ways that they are used to hearing sounds.