Sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound. It thus indicates how loud the headphones are for a given electrical drive level. It can be measured in decibels of sound pressure level per milliwatt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V).[12] Unfortunately, both definitions are widely used, often interchangeably. As the output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's law:
Headphones may be used with stationary CD and DVD players, home theater, personal computers, or portable devices (e.g., digital audio player/MP3 player, mobile phone). Cordless headphones are not connected to their source by a cable. Instead, they receive a radio or infrared signal encoded using a radio or infrared transmission link, such as FM, Bluetooth or Wi-Fi. These are powered receiver systems, of which the headphone is only a component. Cordless headphones are used with events such as a Silent disco or Silent Gig.
A headset is a headphone combined with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. Among applications for headsets, besides telephone use, are aviation, theatre or television studio intercom systems, and console or PC gaming. Headsets are made with either a single-earpiece (mono) or a double-earpiece (mono to both ears or stereo). The microphone arm of headsets is either an external microphone type where the microphone is held in front of the user's mouth, or a voicetube type where the microphone is housed in the earpiece and speech reaches it by means of a hollow tube.
Headphones can prevent other people from hearing the sound, either for privacy or to prevent disturbing others, as in listening in a public library. They can also provide a level of sound fidelity greater than loudspeakers of similar cost. Part of their ability to do so comes from the lack of any need to perform room correction treatments with headphones. High-quality headphones can have an extremely flat low-frequency response down to 20 Hz within 3 dB. While a loudspeaker must use a relatively large (often 15" or 18") speaker driver to reproduce low frequencies, headphones can accurately reproduce bass and sub-bass frequencies with speaker drivers only 40-50 millimeters wide (or much smaller, as is the case with in-ear monitor headphones). Headphones' impressive low-frequency performance is possible because they are so much closer to the ear that they only need to move relatively small volumes of air.
The tech-speak description for this type of headphone is "circumaural," which includes any headphones with earcups that fully enclose your ears. Because of their size and their acoustic isolation, full-size headphones are often considered to be better-suited to home use rather than as a portable option, but the recent popularity of full-size, noise-canceling Beats headphones are challenging the rule.

Portability can mean many things, such as appearance in public, having a secure fit so the headphone doesn’t shift off of your ears, amount of isolation from ambient noise (including active noise canceling), whether the headphone can be worn around the neck when not listening or it requires a carry case, and when extra amplification is required, whether a suitable amp can be found that’s OK to carry along with the portable music player.
Open back usually results in more natural sound, but they leak sound in and out. This means you probably can’t use them in a library or a plane flight since the sound of your music will leak out and disturb the people around you. You also can’t use them on loud public places since noise from the outside will disturb your music. Therefore, even though open back would give you more natural reproduction, for these reasons their use is limited to mostly at home or in the office (if you have your own space that is).
The Elite Active 65t come with three sets of silicone tips and feature an ergonomic design that guarantees a good seal, which is a big reason we prefer them to other true wireless models. With outstanding comfort and excellent passive noise isolation, you get the most out of every note, and you can also lower the volume for less ear strain. Overall sound quality is solid, and sound comes through clear and balanced, with a punchy bass response and a surprisingly dynamic treble range.

Although modern headphones have been particularly widely sold and used for listening to stereo recordings since the release of the Walkman, there is subjective debate regarding the nature of their reproduction of stereo sound. Stereo recordings represent the position of horizontal depth cues (stereo separation) via volume and phase differences of the sound in question between the two channels. When the sounds from two speakers mix, they create the phase difference the brain uses to locate direction. Through most headphones, because the right and left channels do not combine in this manner, the illusion of the phantom center can be perceived as lost. Hard panned sounds are also heard only in one ear rather than from one side.
Telephone headsets connect to a fixed-line telephone system. A telephone headset functions by replacing the handset of a telephone. Headsets for standard corded telephones are fitted with a standard 4P4C commonly called an RJ-9 connector. Headsets are also available with 2.5 mm jack sockets for many DECT phones and other applications. Cordless bluetooth headsets are available, and often used with mobile telephones. Headsets are widely used for telephone-intensive jobs, in particular by call centre workers. They are also used by anyone wishing to hold telephone conversations with both hands free.
Sealed models are ideal for private listening, where you don't want the sound to be heard by other people. Open headphones -- such as foam earpad models and many sports designs -- are acoustically transparent and allow outside sound to be heard by the headphone wearer, and a good deal of the headphones' sound will be audible to anyone near the listener.
Wired headphones are attached to an audio source by a cable. The most common connectors are 6.35 mm (¼″) and 3.5 mm phone connectors. The larger 6.35 mm connector is more common on fixed location home or professional equipment. The 3.5 mm connector remains the most widely used connector for portable application today. Adapters are available for converting between 6.35 mm and 3.5 mm devices.
I’ve never enjoyed the audio quality of Bluetooth headphones, but that’s just me. The sound is better than it ever has been, and it’ll get you 90% of the way there—but not everybody is willing to make that tradeoff. Since USB-C headphones have largely ceded their market advantages over Bluetooth, we have to examine the consumer audio technology’s performance in a world where the headphone jack is disappearing.
The fit isn’t always an easy thing to be sure of when you can’t try before buying, since some ear pads will not have a satisfactory fit to some ears. Power requirements aren’t a simple matter of looking at the impedance, since efficiency or sensitivity doesn’t always track directly with impedance. Another issue indirectly related to power requirements are whether the headphone has the option for ‘balanced’ use or some other connection that isn’t a 3.5 mm or 6.35 mm jack and plug.

Released in 2017, the Bose SoundWear Companion is a different kind of wireless headset. It doesn’t have any earcups or earbuds, but instead it sits around your neck adn has speakers that shoot sound up towards your ear — it’s essentially a portable speaker that sits around your neck. It’s water-resistant, so you can technically work out while wearing it, but it’s really designed for the person who works at home. It’s comfortable enough to wear for lengthy periods of time, but it also has excellent built-in microphones and works great as a speakerphone.
Hearing risk from headphones' use also applies to workers who must wear electronic or communication headsets as part of their daily job (i.e., pilots, call center and dispatch operators, sound engineers, firefighters, etc.) and hearing damage depends on the exposure time. The National Institute for Occupational Safety and Health (NIOSH) recommends sound exposure not exceed 85 dB(A) over 8 hour work day as a time-weighted average.[35] NIOSH uses the 3-dB exchange rate often referred to as "time-intensity tradeoff" which means if sound exposure level is increased by 3 decibels, the duration of exposure should be cut in half. NIOSH published several documents targeted at protecting the hearing of workers who must wear communication headsets such as call center operators,[36] firefighters,[37] and musicians and sound engineers.[38]
Wired headphones are attached to an audio source by a cable. The most common connectors are 6.35 mm (¼″) and 3.5 mm phone connectors. The larger 6.35 mm connector is more common on fixed location home or professional equipment. The 3.5 mm connector remains the most widely used connector for portable application today. Adapters are available for converting between 6.35 mm and 3.5 mm devices.