Hearing aids are distinguished by their technology or circuitry. In the early days, hearing aid technology involved vacuum tubes and large heavy batteries. Today, there are microchips, computerization, and digitized sound processing, used in hearing aid design.
- Conventional analog hearing aids are designed with a particular frequency response based on your audiogram. The audiologist tells the manufacturer what settings to install. Although there are some adjustments, the aid essentially amplifies all sounds (speech and noise) in the same way. This technology is the least expensive and it can be appropriate for many different types of hearing loss.
- Analog programmable hearing aids have a microchip which allows the aid to have settings programmed for different listening environments such as quiet conversation in your home, noisy situations like a restaurant, or large areas like a theater. The audiologist uses a computer to program the hearing aid for different listening situations depending on your individual hearing loss profile, speech understanding, and range of tolerance for louder sounds.
Some aids can store several programs. As your listening environment changes, you can change the hearing aid settings by pushing a button on the hearing aid or by using a remote control to switch channels. The aid can be reprogrammed by the audiologist if your hearing or hearing needs change. These aids are more expensive than conventional analog hearing aids, but generally have a longer life span and may provide better hearing for you in different listening situations.
- Digital programmable hearing aids have all the features of analog programmable aids but use "digitized sound processing" to convert sound waves into digital signals. A computer chip in the aid analyzes the signals of your environment to determine if the sound is noise or speech and then makes modifications to provide a clear, amplified distortion-free signal. Digital hearing aids are usually self-adjusting. The digital processing allows for more flexibility in programming the aid so that the sound it transmits matches your specific pattern of hearing loss. This digital technology is the most expensive, but it allows for improvement in programmability, greater precision in fitting, management of loudness discomfort, control of acoustic feedback (whistling sounds), and noise reduction.