Cordless headphones incorporate one of many technologies to avoid the conventional wire that tethers the headset to the audio source. All cordless headphones use a transmitter and built-in headphone receiver to send and receive audio signals across space wirelessly. The three technologies in use are radio frequency (RF) waves, infrared (IR) light waves, and Bluetooth® technology. Let’s take a look at these in turn.
RF cordless headphones can receive a signal from the headphone’s paired transmitter up to about 300-feet (~100 meters) away in a 360-degree arc. The transmitter must be connected to the audio-out ports of the source, commonly a television or home entertainment center. Radio waves can pass around objects and through walls and ceilings. This makes these headphones convenient for using in the home or office.
Another favorable quality of RF cordless headphones is that the signal remains strong outdoors. For those with patios, pools or barbecues, imagine sitting in the sun, floating on an inflatable raft, or cooking up your favorite meal while listening to music or a television program.
One drawback of RF technology is that it can pick up interference from other radio waves in or near the same frequency band. Cordless phones, wireless networks and even the electric fields radiating from home entertainment equipment or appliances might cause background static or buzzing. RF transmitters are made in various frequency bands, including 900 megahertz and 2.4 gigahertz. You might want to pick a model that uses a different band from your cordless phone. Note too that RF waves can be picked up by eavesdroppers.
Infrared (IR) cordless headphones use a different technology. Rather than broadcasting radio waves, the IR transmitter uses light-emitting diodes (LEDs) to shoot a beam of infrared light, similar to how a remote control works. These headphones must have a clear line of sight to the transmitter, unobstructed by furniture or people passing between the transmitter and receiver. The range of effectiveness is generally up to 30-feet (~10 meters) for basic models. These are ideally intended to use within a single room at fairly close range.
Occupying a different area of the electromagnetic spectrum than radio waves, the advantage of IR cordless headphones is that they do not pick up interference from radio waves, appliances or equipment. And while RF transmitters combine a stereo signal to send, relying on the receiver in the headphones to separate the signal back into stereo, IR models transmit a stereo signal from the base, resulting in claims of a better overall sound experience through cleaner separation of the channels.
Since walls block light waves, the IR signal doesn’t leave the room, making IR cordless headphones a good choice for compartmentalized listening. If you have RF headphones in the living room, you might opt to get the kids IR headphones for their bedrooms. They can each listen to their own music without the signals interfering with each other or with your RF headphones. IR is also a good choice for any setting that requires privacy, such as a doctor’s office, courtroom or boardroom Additionally, infrared won’t interfere with nearby equipment, making it safe to use in places like hospitals or aboard airplanes.
Bluetooth® cordless headphones are yet another technology. These headphones are made for use with mobile personal electronics. Some applications include hands-free cell phone use, MP3 players, and personal digital assistants (PDAs). Bluetooth® technology creates a Personal Area Network (PAN), pairing devices together for interoperation. The connected or networked devices use radio waves to communicate, but with a less robust radio than RF headphones. This saves power, paramount to battery-run personal devices. It also results in a shorter effective range, however, comparing roughly to that of infrared without the obstruction restrictions. Bluetooth® signals can interfere with other radio wave devices, however, including RF headphones.