One of the best ways to improve speech intelligibility for a hearing aid user in noisy environments is to use a directional microphone system in the hearing aid.
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A conventional hearing aid microphone (omnidirectional) is equally sensitive to all incoming sounds, regardless of the direction of the sounds. No sounds are reduced in relation to others. Directional microphones are optimised to be less sensitive to sounds from a specific direction, often in such a way that they are more sensitive to sounds from the front than from behind.
Directional microphone systems can be designed in many different ways. A common feature is the use of several microphone inlets and subsequent signal processing to allow the system to distinguish among sounds from different directions. In that way, it is possible to emphasise sounds from the front over those from behind.
A directional microphone system can consist of either one microphone with several inlets or of two electronically coupled microphones. There are advantages of both systems.
Directional microphone systems with a single microphone have proven their worth for many years but are restricted in functionality because they most often only reduce sounds from one specific direction.
Directional microphone systems with two microphones have a wider choice in signal processing but are technically more challenging. Mastering these technical challenges has made it possible to design, for example, an adaptive directional system that automatically assesses which direction noise comes from and reduces it.
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Hearing aid components
