When trying to understand the difference between analog and digital hearing aids, you need to first understand the history of analog vs digital, and the alternative ways that they process and amplify sounds. Historically, analog technology appeared first, and as a result the majority of hearing aids were analog until digital signal processing (DSP) was invented, after which digital hearing aids appeared. At this point, the majority (90%) of the hearing aids sold in the United States are digital, although analog hearing aids are still offered because they’re often less expensive, and because some people prefer them.
The way that analog hearing aids work is that they take sound waves from the microphone in the form of electricity and then amplify them, sending louder versions of the sound waves to the speakers in your ears “as is.” In contrast, digital hearing aids take the very same sound waves from the microphone, however before amplifying them they turn the sound waves into the binary code of ones and zeros that all digital devices understand. After the sound has been digitized, the micro-chip inside the hearing aid can manipulate the data in sophisticated ways before transforming it back to analog sound and passing it on to the ears.
Both analog and digital hearing aids perform the same work – they take sounds and amplify them to allow you to hear better. Both types of hearing aids can be programmed by the dispensers of the hearing aids to create the sound quality that each user desires, and to create settings appropriate for different listening environments. The programmable hearing aids can, for example, have one particular setting for use in quiet rooms, another for listening in loud restaurants, and still another setting for listening in large stadiums.
But beyond programmability, the digital hearing aids often offer more controls to the wearer, and offer additional features because of their capacity to manipulate the sounds in digital form. They have an array of memories in which to save more location-specific settings than analog hearing aids. They can also use advanced rules to identify and reduce background noise, to eliminate feedback and whistling, or to selectively detect the sound of human voices and “follow” them using directional microphones.
In terms of price, analog hearing aids are in most cases less expensive, although some digital hearing aids are nearing the cost of analog devices by removing the more state-of-the-art features. 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 to hearing sounds.