How Do Infrared Headphones Work?by Isaiah David
Sound comes out of the stereo system through audio cables and into an infrared transmitter. The transmitter turns the sound into a series of pulses. The pulses work like bits in a computer, digitally capturing the sound information. These pulses are then sent to an infrared LED (a light emitting diode.)
The LED is a device which produces light at a particular wavelength. The infrared LED produces long wavelength infrared light. It can not be seen with the naked eye, but works much like visible light. It can reflect off of mirrors, for example, and can be blocked by any objects in the way. Because of this, infrared headphones can only be used when they are within a line of sight of the transmitter.
The headphones pick up the light with a receiver and turn it back into sound. The Receiver has an infrared CDS cell, which produces a pulse of electricity every time infrared light lands on it. The cell is designed to pick up the particular frequency of light produced by the transmitter, so it is not disturbed or thrown off by other light. A small computer inside of the receiver takes these pulses of electricity and turns them into an audio signal. This audio signal is then amplified and sent to the headphones themselves, which play the sound.