An assistive listening device is a technical tool to assist people with hearing loss, with or without a hearing aid. It brings the speaker’s voice directly to the ear filtering distant and surrounding noise. An assistive listening device is also known as an alerting device(alarm clock, baby crier, door knocker etc.). An Assistive listening device (ALD) is used to improve hearing ability for people in a variety of situations. A common usage is to aid people who are hard of hearing (HOH). by amplification and better sound to noise ratio (SNR). The ALD may be used to help HOH people hear televisions and other audio devices and also to help people hear speech through public address (PA) systems such as in synagogue or at a lecture.The assistive listening device usually uses a microphone to capture an audio source near to its origin and broadcast it wirelessly over an FM (Frequency Modulation) transmission, IR (Infra Red) transmission, IL (Induction Loop) transmission, or other transmission method. The person who is listening may use an FM/IR/IL Receiver to tune into the signal and listen at his/her preferred volume. This receiver can be headphones for example. Within them they can also choose the volume which suites them best.
