A headset combines a headphone with a microphone. Headsets are made with either a single-earpiece (mono) or a double-earpiece (mono to both ears or stereo). Headsets provide the equivalent functionality of a telephone handset but with hands-free operation. They have many uses including in call centers and other telephone-intensive jobs and for anybody wishing to have both hands free during a telephone conversation.
Telephone headsets generally use 150-ohm loudspeakers with a narrower frequency range than those also used for entertainment. Stereo computer headsets, on the other hand, use 32-ohm speakers with a broader frequency range.
Mono, stereo, and surround
Headsets are available in single-earpiece and double-earpiece designs. Single-earpiece headsets are known as monaural headsets. Double-earpiece headsets may support stereo sound or use the same audio channel for both ear-pieces. Monaural headsets free up one ear, allowing interaction with others and awareness of surroundings. Telephone headsets are monaural, even for double-earpiece designs, because the telephone offers only single-channel input and output. For computer or other audio applications, where the sources offer two-channel output, stereo headsets are the norm; use of a headset instead of headphones allows use for communications (usually monaural) in addition to listening to stereo sources.
Virtual surround headsets feature ear cups that cover the entire ear. This type of headset uses only two discrete speakers, one on each ear cup, to create surround sound. Virtual surround headsets tend to have higher-end driver components which experts and consumers believe to be more durable, as well as have larger speakers that deliver more powerful and dynamic sound quality. Virtual surround headset achieves surround sound by using external or internal pre-amplifier or mix-amplifier modules, as well as several different algorithms, to convert stereo or surround sound signals into surround sound. The sound is divided and sectioned so as to deliver it in such a way that it creates an auditory landscape, thereby producing surround sound.
The microphone arm of headsets may carry an external microphone or be of the voice tube type. External microphone designs have the microphone housed in the front end of the microphone arm. Voicetube designs are also called internal microphone design, and have the microphone housed near the earpiece, with a tube carrying sound to the microphone.
Most external microphone designs are of either omnidirectional or noise-canceling type. Noise-canceling microphone headsets use a bi-directional microphone as elements. A bi-directional microphone's receptive field has two angles only. Its receptive field is limited to only the front and the direct opposite back of the microphone. This creates an "8" shape field, and this design is the best method for picking up sound only from close proximity of the user, while not picking up most surrounding noises.
Omni-directional microphones pick up the complete 360-degree field, which may include much extraneous noise.
Standard headsets with a headband worn over the head are known as over-the-head headsets. Headsets with headbands going over the back of the user's neck are known as backwear-headsets or behind-the-neck headsets. Headsets worn over the ear with a soft ear-hook are known as over-the-ear headsets or earloop headsets. Convertible headsets are designed so that users can change the wearing method by re-assembling various parts.