To fully 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 amplify and process sounds. Analog technology appeared first, and consequently 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 purchased in the US are digital, although analog hearing aids are still sold because they are often less expensive, and because some people prefer them.
The way that analog hearing aids operate is that they take sound waves from the microphone in the form of electricity and then amplify the waves, delivering louder versions of the sound waves to the speakers in your ears “as is.” On the other hand, digital hearing aids take the very same sound waves from the microphone, however before amplifying them they turn them into the binary code of ones and zeros that all digital devices use. This digital data can then be altered in numerous complex ways by the microchip within the hearing aid, before being converted back into ordinary analog signals and delivered to the speakers.
Remember that analog and digital hearing aids have the same function – they take sounds and boost them so you can hear them better. Both analog and digital hearing aids can be programmable, which means that they contain microchips which can be modified to adjust sound quality to match the individual user, and to develop various configurations for different environments. For example, there can be distinct settings for low-noise rooms like libraries, for busy restaurants, and for outdoor spaces like stadiums.
But beyond programmability, the digital hearing aids generally offer more controls to the wearer, and have additional features because of their capacity to manipulate the sounds in digital form. They have multiple memories in which to save more environment-specific settings than analog hearing aids. Other capabilities of digital hearing aids include the ability to automatically reduce background noise and remove feedback or whistling, or the ability to prefer the sound of voices over other sounds.
Cost-wise, most analog hearing aids are still 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.