Wednesday, August 02, 2006
Telecoils (T-coils) allow different sound sources to be directly connected to the hearing aid, improving sound quality and allowing the hearing aid wearer to easily perceive the signal of interest in almost any environment, and regardless of background noise. They can be used with telephones (phone hearing impaired), FM systems, induction loop systems and public address systems.
T-coils are comprised of a metal core (or rod) around which ultra-fine wire is coiled. T-coils are also called induction coils because when the coil is placed in an electromagnetic (EM) field, an alternating electrical current is induced in the wire (Ross, 2002b; Ross, 2004). The T-coil detects EM energy and transduces (or converts) argosy hearing it to electrical energy (phone hearing impaired ). T-coils can also be used to pick up magnetic signals, just as a microphone picks up an acoustic signal; argosy hearing the T-coil then sends the signal to the hearing aid circuit or processor for amplification.
DAI-direct audio input allows the hearing aid to be connected to an external audio source like a CD player or an assistive listening device (ALD). This is preferred by many users, as opposed to using a T-coil with a standard set of headphones, as there is less interference (usually heard as a buzzing noise so as hearing aids prices).