Amplifiers take the resulting signal and make it louder. The receiver converts the signal back into the acoustical form of the signal that the ear can hear. There are several choices which can be ordered from manufacturers for specific hearing losses. The goal is to provide some degree of amplification of the in-coming signal, as accurately as possible. Amplifier Options Amplifiers maintain the frequency response of the microphone.
All amplifiers generate some form of distortion.
A good amplifier produces a large, completely accurate, undistorted copy of the input signal from the microphone. The Class A amplifier is the amplifier first introduced in hearing aids. Therefore it is the least expensive and best understood amplifier. The Class A amplifier has low harmonic distortion at low input levels, but tends to have very high levels of distortion as the input levels rise. This amplifier is always on , that means the amplifier has current drain regardless of whether the individual is listening to something or sitting in a quiet room.