Important Advances for People with Hearing Loss Around the World

Hearing aids don't work in noise has been the most commonly heard complaint about hearing aids since electronic aids were introduced at the start of this century. Now, at the end of the century, hearing aids are providing significant help in noisy places such as restaurants and meetings, and there is promise of even more benefits in the near future.

The digital revolution created major breakthroughs in hearing aid technology, leading to the introduction of digital hearing aids. Newspaper, radio and television news accounts generated tremendous interest in these hearing aids, which use miniaturized microprocessors to digitize and process incoming acoustic signals.
Another, equally important advance has received less media attention, perhaps because it is not as familiar as the concept of digital. However, advances in microphone technology, especially when coupled with the capabilities of digital processing, are already providing impressive results for people with hearing loss.

Directional Microphones

Directional microphones have been available for years. Most commonly, dual microphones have been used to achieve directional amplification. The benefits of directional amplification can be expressed as an improvement in the signal-to-noise ratio (the higher the s/n ratio, the better the resulting hearing in noise) or as an actual word recognition score in a given noisy condition.

Audiologic research has consistently demonstrated the benefits of directional amplification. In recent years, however, there has been more interest in miniaturization and directional microphones have not been commonly used.

Recent developments have led to the introduction of matched dual microphones and multi-microphone arrays. Laboratory studies have measured improved signal-to-noise ratios in the 4 to 8 dB range, significantly better than the 2 to 4 dB improvement for earlier directional microphones. Clinical measurements have yeilded scores for word recognition in noise that are 10 to 20% better than with conventional omnidirectional microphones. Not surprisingly, studies have not indicated any multi-microphone advantage in quiet situations.

Multi-microphone technology is already providing important benefits for hearing aid users, but these instruments are not suitable for everyone. In addition to added expense, many hearing aid users may not want to use a directional switch (although this can be eliminated), or may want the smallest instrument possible. Still, a number of researchers believe this technology holds the greatest promise for improved hearing and that in the near future many people with hearing loss will be able to hear as well in noise as their friends with normal hearing.
If you have any questions about directional microphones please call or e-mail and we'll do our best to help you.