Infrared (IR) headphones can be used for listening to music or television cordlessly. The headphones utilize a transmitter that connects with audio cables to the audio source, such as a home entertainment center. The transmitter utilizes light-emitting diodes (LEDs) to direct a focused beam of pulsating, invisible light towards a receiver built into the headphone set. The pulsations act as on/off signals that are translated digitally by the receiver into audible sound waves. Most infrared headphones have an effective range of about 30 feet (~10 meters) or less, and require a clear line of sight between transmitter and receiver.
Infrared light waves are longer than visible light waves but shorter than radio waves. The longest light waves visible to the human eye are at the red end of the light spectrum. The Latin word, infra means “below” making infrared literally mean “below red.” Within the infrared spectrum there are many frequency bands utilized for different purposes from thermal imaging technologies to night-vision glasses. The section of the IR spectrum set aside for wireless communications is utilized by infrared headphones.
Most everyone has had the experience of pointing a remote control at a component trying to get the component to respond. Obstacles in the way will block infrared light waves, and the beam of light produced cuts a somewhat narrow swath from sender to receiver. In other words, you have to point the remote at the device to get it to work.
Infrared headphones have similar restrictions, though technologies for diffusing the light beam have improved to create a wider swath so that someone need not be directly in front of the transmitter to get a good signal. Some models also incorporate a tri-directional receiver in the headset so that the connection between the transmitter and headphones is not broken when the wearer turns his or her head away, inadvertently pointing the receiver away from the transmitter.
Infrared headphones compete with cordless radio frequency (RF) headphones for the home entertainment market. Radio waves broadcast outward in all directions from an RF transmitter and can pass through walls and around objects, lacking the restrictions of infrared headphones. However, RF models can pick up static and buzzing from other devices while infrared is not affected by radio waves. Another advantage of infrared headphones is that a stereo signal is sent from the transmitter to the receiver, providing an arguably better quality of sound that RF headphones that combine both channels at the transmitter, then demodulate them at the receiver.
Since the light waves of infrared headphones do not pass through walls, listening is private. This makes them superior to RF headphones if you have children with their own bedrooms who would like the option of listening to music, television or even a computer cordlessly. RF headphones have a range of a few hundred feet (~100 meters) and signals would overlap and interfere with each other. Using infrared headphones in each bedroom, the occupants can listen to what they like without bothering each other (or RF headphones in the living room).
Infrared is also preferable in professional settings that require privacy, such as a classroom, convention room, boardroom or courtroom. Another advantage of infrared headphones is that they won’t interfere with nearby sensitive electronic equipment, making them ideal for hospitals and control rooms. They are a poor choice for outdoor use, however, as sunlight weakens infrared waves.
If you’ll be using your infrared headphones with the home entertainment center, look for a model that incorporates Dolby® technologies to decode surround sound movies. It’s also a good idea to read online customer reviews from people who have purchased infrared headphones to see which models sound like they deliver the best performance for the money. More expensive models don’t always translate to better audio quality. Finally, if you are an audiophile you might find that the advantage of being wireless comes with acoustic caveats, although research can reduce the compromise.