The first method of noise reduction is the use of directional microphones. These were available prior to the advent of the digital technology, but digital technology allows us to do more with directional technology. Some hearing aids are able to automatically identify and prioritize sounds coming from the front. This does not eliminate noise from behind, but it does minimize it and emphasize what you are focusing on.
Digital Noise Reduction
The computer in the hearing aid analyzes the kind of sound coming into the hearing aids. The hearing aid looks at frequency, modulation and amplitude of the incoming signal to determine if the sound is speech or noise. When noise is suspected in given frequency range the volume for that frequency band can be reduced.
This is the opposite of the concept discussed under Digital Noise Reduction. The computer in the hearing aid increases volume for a given frequency band when speech is present.
The role of the audiologist in fitting hearing aids has become more critical as the devices have become more sophisticated. Computer driven hearing aids will do what they are programmed to do. it is important that the person programming your hearing aids has a good knowledge of your hearing and environments so that you can hear as well as possible.