A hearing aid is a sophisticated electronic device that can receive and amplify incoming sounds for people with hearing impairment to enhance their speech understanding in daily life. The basic components of a hearing include a microphone, amplifier and receiver. The speech signals are captured by the microphone, which converts the signal into the electrical signals then send them to the amplifier. The amplifier amplifies the electrical signals then transmits them to the user’s ear through the receiver.
Modern digital hearing aids have more function than amplification of sounds only. Most modern hearing aids offer multichannel technology. A channel is a filter that covers the range of frequencies analyzed, processed and reproduced by the hearing aid. Since the hearing thresholds at different frequencies of hearing aid user may be different, hearing aids with more channels can give accurate amplification at discrete frequency for the user, and thus result in better sound quality. More advanced technology, such as noise reduction, directionality and feedback control, is usually correlated to the number of channels.
Modern hearing aids also adopt wide dynamic range compression to ensure the audibility of soft and medium input, while limits the output of loud sounds to ensure listening comfortability.