0_Wizard
Headphones are important sometimes.  They allow me to listen to an audio source without anyone nearby hearing.
Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear.
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Headphones
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Headphones
Headphones (or head-phones in the early days of telephony and radio) are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earspeakers, earphones or, colloquially, cans. Circumaural and supra-aural headphones use a band over the top of the head to hold the speakers in place. The other type, known as earbuds or earpieces consist of individual units that plug into the user's ear canal.
Hearing aid
A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers such as PSAPs or other plain sound reinforcing systems cannot be sold as "hearing aids". Early devices, such as ear trumpets or ear horns, were passive amplification cones designed to gather sound energy and direct it into the ear canal. Modern devices are computerised electroacoustic systems that transform environmental sound to make it audible, according to audiometrical and cognitive rules.
Headphone amplifier
A headphone amplifier is a low-powered audio amplifier designed particularly to drive headphones worn on or in the ears, instead of loudspeakers in speaker enclosures. Most commonly, headphone amplifiers are found embedded in electronic devices that have a headphone jack, such as integrated amplifiers, portable music players (e.g., iPods), and televisions. However, standalone units are used, especially in audiophile markets and in professional audio applications, such as music studios. Headphone amplifiers are available in consumer-grade models used by hi-fi enthusiasts and audiophiles and professional audio models, which are used in recording studios.
Bose headphones
Bose Corporation produces headphones for consumer, aviation and military use. The models range includes in-ear headphones, mobile headsets, supra-aural headphones, Circumaural headphones and military/aviation headsets. The company was the first to release active noise cancelling headphones as a consumer product. Bose's consumer range of active noise-cancelling headphones are called "QuietComfort". For industrial noise-cancelling applications, Bose produces the A20 Aviation Headset, Space Shuttle Headset and Combat Vehicle Crewman Headset. According to Bose, the company started noise-cancellation involvement after Dr. Amar Bose went on a 1978 flight to Europe, and "was trying out new set of airline-supplied headphones and found that he couldn't really enjoy the sound with the roar of engines in the background".
Binaural recording
Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments. This effect is often created using a technique known as "dummy head recording", wherein a mannequin head is outfitted with a microphone in each ear. Binaural recording is intended for replay using headphones and will not translate properly over stereo speakers. This idea of a three dimensional or "internal" form of sound has also translated into useful advancement of technology in many things such as stethoscopes creating "in-head" acoustics and IMAX movies being able to create a three dimensional acoustic experience.
Disc jockey
A disc jockey (DJ) is a person who plays existing recorded music for a live audience. Most common types of DJs include radio DJ, club DJ who performs at a nightclub or Music festival and turntablist who uses record players, usually turntable, to manipulate sounds on the phonograph record. Originally, the "disc" in "disc jockey" referred to gramophone records, but now "DJ" is used as an all-encompassing term to describe someone who mixes recorded music from any source, including vinyl records, cassettes, CDs, or digital audio files stored on USB stick or laptop. DJs typically perform for a live audience in a nightclub or dance club or a TV, radio broadcast audience, or in the 2010s, an online radio audience.
Whole House Audio
Whole House Audio (distributed audio) systems are audio systems that allow for playback and often control of music throughout an entire home or building. Numerous commercial systems provide this function, or a system can be custom built or homemade. Whole house audio systems can be classified as: single source-single zone, single source-multiple zone or multiple source-multiple zone. These systems distribute the same audio source everywhere—individual rooms must listen to the same audio source. This is the simplest type of system that can be installed. If designed properly, no special equipment is required other than one amplifier and a desired audio source.