Digital hearing aids

Digital hearing aids are instruments that use digital technology to process sound signals.

What is digital signal processing?

In many hearing aids, signal processing is digitalised.

The central part of a digital hearing aid is the digital signal processor. The pro-cessor can be compared with a kind of calculator or computer.

As the processor is in itself a computer, it can be programmed with scientific mod-els for sound and hearing. This widens the range of possibilities in digital hearing aids compared to analog hearing aids and gives greater freedom and audiological challenges. At the same time, it prepares the way for several different types of digital hearing aids.

How does digital signal processing work?

Hearing aids comprise three main components:

A microphone, which picks up sounds from the surroundings

A signal processor, which amplifies and processes the sound signals

A receiver (loudspeaker), which reproduces the processed sound signals

The microphone delivers the incoming analog signal to an analog-to-digital con-verter (ADC). This converts the signal to a series of numeric values, which can then be processed by the digital signal processor.

After processing, the numeric values are converted back into an analog signal by a digital-to-analog converter (DAC).

Digital signal processing gives the following possibilities:

Adjustment of details of the sound without destroying the general patterns of the sound.

Damping of noise.

Enhanced speech intelligibility.

Automatic amplification – eliminating the need for a manual volume control (VC) in many cases and eliminating problems with feedback whistling.

Elimination of audible internal hearing aid noise