Audio Headphones

Audio headphones are small speakers worn over the ears to isolate sounds for the listener. They use three basic technologies: standard, wireless, and infrared. Standard audio headphones, headsets and ear buds use wires to receive an electrical signal from a transmitter. As the current through an electromagnet varies with the signal, the headphone diaphragm vibrates in response. Wireless headphones are cordless, battery-powered audio headphones which receive radio frequency (RF) signals, typically at 900 MHz. Listeners can travel anywhere within a specified range and still receive audio outputs. Infrared headphones use infrared (IR) light to carry data from a transmitter to a receiver. The transmitted signal is converted to an electrical impulse which drives the speakers in the headset. Unlike wireless headphones, however, IR headsets require listeners to remain within a transmitter’s line of site.

Noise cancelling headphones and noise reduction headphones are specialized audio headphones which use active noise control (ANC) technology to reduce unwanted ambient sounds and other acoustic noise. Noise-cancelling headphones consist of a microphone placed near the ear and electronic circuitry which generates a sound wave with the opposite polarity of the sound wave which arrives at the microphone. Most noise-reducing headphones are battery-powered devices which are bulkier than standard audio headphones. Because of the shorter wavelengths of high-frequency sounds, these audio headphones are less effective at higher frequencies. They vary in terms of cost and quality, and may pick up stray electromagnetic signals from mobile telephones.

Selecting audio headphones requires an analysis of performance specifications and product features. As a rule, audio headphones with higher impedances require more electrical energy to drive the headset speakers. Weight and portability are also important considerations. Earbuds, in-ear headphones and headphones with clip-on earpieces are designed for active personnel. Sealed headphones are suitable for listening in noisy environments which require sonic isolation. Open headphones provide superior sound quality because they are less likely to produce unwanted resonance. Audio headphones such as Apple in-ear headphones, iPod headphones, Bluetooth? headphones and computer headphones are consumer-oriented products. Apple and iPod are registered trademarks of Apple Computer, Inc. Bluetooth is a registered trademark of Bluetooth Special Interest Group (SIG), a trade association.

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Part Numbers for Audio Headphones