Analog or Digital – What’s the Difference?

Electronic hearing aids have been with us for over 50 years. The basic design principle is still in use today – take a sound and make it louder so it can be more easily heard. Traditional hearing aids use analog circuitry – that is, the sound signal is processed entirely in the analog domain, which is how humans normally perceive sound. Technological Innovation in Hearing Aids Recently, a new type of hearing aid has appeared on the market – the digital hearing aid. These devices allow sound to be processed in various ways. The processing can help to improve the clarity of desired sounds while eliminating background noise or other unwanted sound. To get a better idea of the advantages or disadvantages of each type of hearing aid, let’s look a bit at how they have evolved over the years. The earliest transistor hearing aids were simple amplifiers. They made everything louder. In quiet environments, this helped a person with hearing loss to better comprehend speech or television or radio. In noisy environments, however, the hearing aid was often a disadvantage – the amplified background noise would simply be too distracting.

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The next step in hearing aid technological evolution was to make them adjustable. The audiologist would measure the patients hearing loss and send the specifications to a laboratory which would build a customized hearing aid. The device could be individually tailored for specific hearing problems using frequency analysis and filters. This way, the entire spectrum of sound is not amplified, but just the particular frequencies that the patient needs.

Programmable Hearing Aids

Adjustable hearing aids were a significant improvement, but the ability to adjust hearing aids didn't address the problem of hearing needs in different noise environments. The programmable hearing aid was thus designed to be user adjustable for different situations. The device could be adjusted by a remote control, allowing the patient to apply different filters and settings according to need.

Programmable devices were a step forward, but there were still limitations in the number of different settings available to the user.

Digital Hearing Aids

Digital hearing aids first came on the market in the late 1980’s. Their use of digital signal processing (DSP) allowed a much more flexible approach to adjusting frequency amplification. Unfortunately, the earliest digital models were quite bulky and had a short battery life, so they were relatively unsuccessful on the market.

By the late 1990’s, the technology had improved to the point where digital hearing aids were a practical alternative. Their high cost was offset by the improved signal processing offered over analog devices.

The advantages of digital hearing aids lie solely in their ability to process sound. The audiologist has many options available to tailor the device to the patients needs. Individual frequency bands can be amplified or reduced, and the shape of the frequency band can also be set.

Digital Hearing Aid Components

Digital hearing aids have five components: the microphone, the analog to digital converter, the processing unit, the digital to analog converter and the receiver. Sound is picked up by the microphone and then converted into digital information. The processing unit changes the sound according to what kind of hearing loss the patient experiences. After the processing, the sound is converted back to analog and fed into the receiver so the user can hear the sound.

The processing unit is what gives digital hearing aids an edge over their analog counterparts. Digital Signal Processing allows certain parts of the sounds – bands of frequencies – to be amplified, while at the same time reducing unwanted frequencies. Digital hearing aids can amplify and filter sound with much more precision than analog technology. Thus, vocal frequencies can be focused on while removing distracting background ambient noise.

Digital Hearing Aid Features

Feedback, that high pitched squealing noise that often occurs when adjusting the volume of an analog hearing aid, can be eliminated with digital units. The digital hearing aid monitors for feedback, and prevents it by applying a suppression mechanism.

Digital hearing aids also frequently come with directional microphones, which allows the wearer to focus on sounds in front of them, while eliminating sounds coming from behind them. This can be especially beneficial to counteract the “cocktail party effect” frequently encountered in crowded situations where the hearing aid wearer is trying to speak with the person in front of them, but they are surrounded by noise.

Digital hearing aids often have the ability to switch settings for different situations. This allows the wearer to select an optimal amplification function depending on whether the environment is noisy or quiet, or whether you are listening to music or talking to someone.

Digital hearing aids are more expensive than analog, but as the technology continues to improve and manufacturing procedures become more commonplace, the price will surely decrease. We are seeing greater miniaturization in the computer field, and this will spill over into providing smaller and more effective hearing aids in the future.

Of course, good hearing aids are only part of the solution. Skilled. professional programming and fitting, like that provided by the audiologists at the Hearing Device Center of the California Ear Institute, acoustical modifications and Assistive Listening Devices are also necessary to creating the optimal listening environment for any individual with hearing impairment.

Quality hearing aids programmed by skilled professionals, like the audiologists at the Hearing Device Center of the California Ear Institute and Assistive Listening Devices are necessary to creating the optimal listening environment for any individual with hearing impairment. Click here to make an appointment to improve your hearing today !

For more information about hearing aids, visit these manufacturer’s web sites:

Starkey Laboratories
Widex
Phonak
Unitron Hearing
Beltone
Siemens
GN ReSound