When trying to understand the difference between analog and digital hearing aids, it is important to first understand the history of analog versus digital, and the alternative ways that they amplify and process sounds. Historically, analog technology appeared first, and consequently the majority of hearing aids were analog until digital signal processing (DSP) was invented, at which point digital hearing aids appeared. Most (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 often less expensive.
Analog hearing aids handle inbound sounds by taking the electrical sound waves as they emerge from a microphone and amplifying them “as is” before sending them to the speakers in your ears. On the other hand, digital hearing aids take the very same sound waves from the microphone, but before amplifying them they turn them into the binary code of ones and zeros that all digital devices use. After the sound is digitized, the micro-chip within the hearing aid can process and manipulate the information in sophisticated ways before transforming it back to analog sound and passing it on to your ears.
Both analog and digital hearing aids perform the same function – they take sounds and amplify them to enable 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 environments. For example, there can be distinct settings for quiet rooms like libraries, for noisy restaurants, and for large areas like sports stadiums.
Digital hearing aids, because of their ability to manipulate the sounds in digital form, generally offer more features and flexibility, and are often 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 human voices over other sounds.
In terms of price, analog hearing aids are generally less expensive, although some digital hearing aids are approaching the price of analog devices by removing the more sophisticated features. Hearing aid wearers do detect a difference in the sound quality produced by analog versus digital hearing aids, but that is largely a matter of personal preference, not really a matter of whether analog or digital is “better.”