Digital Hearing Aids

Hearing Loss does not have to mean isolation.  With the wide variety of styles and today’s highly advanced hearing aids, you can compensate for many hearing difficulties.  Until recently, hearing aids were limited to amplifiers with volume and tone controls.  This meant that when conventional hearing aid users turned the volume up to hear soft sounds, loud sounds would be made uncomfortably loud. So, while these devices were effective in a quiet room, they were not comfortable to listen to in more complex listening situations.  Frequently users of analog hearing aids were adjusting the volume up and down to control loud and soft sounds.  Often times, hearing aids ended up in pockets, or worse, drawers as users grew frustrated with their limitations.

Researchers and engineers have known for over 20 years that digital signal processing would offer unique solutions to those with hearing loss.  The challenge was to engineer such a system that could run on a small hearing aid battery and was tiny enough to fit into a hearing instrument. Digital signal processing (DSP) is the same technology that is used in CD recording, processing and playback.  It changes sound into numbers that a computer can manipulate mathematically and then transforms the numbers back into an acoustic signal that the human ear can hear.

These digital recipes are called algorithms. It is the mathematical recipes that distinguish one digital hearing aid from the other. By using numbers to manipulate sound, digital hearing instruments can do things that conventional and programmable hearing instruments cannot do. Digital hearing aids can divide the sounds into many components based on frequency, time, or intensity information and apply different algorithms to manipulate the sound for a given individual. This results in a more precise tuning of the sound shape for the hearing impaired user.  Digital hearing aids automatically perform feedback suppression, speech enhancement, noise reduction, and pattern recognition. Digital hearing aids can also monitor the battery voltage resulting in less drain and increased battery life.

The best part of this technology is that all these adjustments happen automatically for the user.  So, as complicated as this all sounds, the user doesn’t even have to worry about the technical part.  In fact, from an ease of use point of view, digital hearing aids are easy to use… just put them in your ear and go.

Digital technology is more stable over time.  There are fewer components to go wrong and fewer components that are susceptible to moisture and aging changes.  This means that the sound you experience on the first day you receive the hearing aid stays consistent until the program is changed. 

Most major companies are offering digital hearing aid technology in their product lines.  The first digital hearing aid, however, was introduced by Madison‘s own Nicolet Instrument Corp. in 1989.  For a variety of reasons, the Nicolet project folded in 1991 and it wasn’t until the spring of 1996 that Oticon and Widex introduced digital hearing aids in behind-the-ear and in-the-ear styles.  In April 1997, Widex announced the first to introduce the Senso Completely-In-the-Canal (CIC) instrument.  In 1998 it introduced the world’s first 100% digital hearing aid for severe to profound losses. Many hearing aids are combining digital processing with the use of directional microphones to improve hearing in difficult listening environments.

User satisfaction is also high. An independent study by Hall and Sandlin (1997), found that experienced hearing aid users preferred digital hearing aids over analog hearing aids. They were more satisfied with the performance when hearing in noisy environments and listening to music. In a separate study at Cleveland Clinic, users showed a significant preference for digital over conventional or programmable instruments.