Analogue circuits enable adjustment of the appliance’s frequency response through potentiometers (trimmers) which the hearing-aid specialist sets with a small screwdriver. This type of circuit is characterized by considerable sturdiness and by the possibility of obtaining very high outputs, and therefore able to improve even very serious hearing problems. On the other hand the presence of mechanical components (trimmers) makes the hearing-aid sensitive to variations in temperature and humidity. This type of appliance is not very flexible, with limited programming possibilities and often a low quality of sound.
| Programmable hearing-aids |
Programmable circuits are characterized by absence of the analogue “trimmers”. In these appliances, adjustments are memorized in the electronic circuits through connection to a computer. The exceptionally small size of the circuit also enables a much higher number of parameters to be memorized, for an adjustment precision unattainable with analogue hearing-aids. Programmable appliances can also store various adjustments which, simply by pressing a button on the hearing-aid, enable the user to obtain the best results in the various surrounding conditions.
Digital hearing-aids are the most evolved from a technological standpoint because they process the signal like real computers. The input sounds are digitalized and subsequently processed by the appliance’s circuit in order to improve the hearing loss. In addition to this processing, digital appliances are able to recognize noise, and lower the amplification to enable the hypoacusis patient to better understand speech in noisy places. The particularly small size and the technical characteristics of these circuits make digital hearing-aids the state-of-the-art in hearing improvement.
