Digital Signal Processing (DSP)
Digital signal processing (DSP) hearing aids convert sounds entering the microphone into ‘digitized’ codes. To do so, digital hearing aids must analyse the incoming sound at regular intervals. The more frequently the hearing aid does this per second, the more accurate the digitized codes will be. The number of times a digital hearing aid analyses sounds per second is called the ‘sampling rate’.
The digital hearing aids then break-up the digitized codes into ‘bits’. Without this process two very similar, but not identical, sounds will have the same digitized code and therefore be perceived as the same sound. The greater the number of bits the digitized code can be broken up into, the more precisely the hearing aid can distinguish between sounds of similar nature.
Once sounds have been converted into digitized codes and broken into bits, they are separated into different frequency channels. This allows the digital hearing aid to then be precisely fine-tuned at each frequency channel according to your individual hearing loss and listening needs. Other digital signal processing (i.e. noise reduction, compression, directionality) also occurs at this stage Afterwards, the digitized codes are recombined and brought back together as one.
The final stage is for the digital hearing aid to convert the digitized codes back into sounds to it can heard by the hearing aid wearer. It is the receiver (loudspeaker) that carries out this task.