Headphones: An Overview
HEADPHONES are a pair of small loudspeakers that are designed to be held in place close to a user's ears. They are also known as ear speakers, earphones or, colloquially, cans. The alternate in-ear versions are known as ear buds or earphones. In the context of telecommunication, a headset is a combination of headphone and microphone. Headphones either have wires for connection to a signal source such as an audio amplifier, radio, CD player, portable media player, mobile phone, electronic musical instrument, or have a wireless receiver, which is used to pick up signal without using a cable.
HISTORY
Headphones originated from the earpiece, and were the only way to listen to electrical audio signals before amplifiers were developed. The first truly successful set was developed in 1910 by Nathaniel Baldwin, who made them by hand in his kitchen and sold them to theUnited States Navy.
Some very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature.
The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire; impedance of 1000 to 2000 ohms was common, which suited both crystal sets and triode receivers. In early powered radios, the headphone was part of the vacuum tube's plate circuit and had dangerous voltages on it. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely grounded. The use of bare electrical connections
HISTORY
Headphones originated from the earpiece, and were the only way to listen to electrical audio signals before amplifiers were developed. The first truly successful set was developed in 1910 by Nathaniel Baldwin, who made them by hand in his kitchen and sold them to theUnited States Navy.
Some very sensitive headphones such as those manufactured by Brandes around 1919 were commonly used for early radio work. These early headphones used moving iron drivers, either single ended or balanced armature.
The requirement for high sensitivity meant no damping was used, thus the sound quality was crude. They also had very poor comfort compared to modern types, usually having no padding and too often having excessive clamping force to the head. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had to be more sensitive and were made with more turns of finer wire; impedance of 1000 to 2000 ohms was common, which suited both crystal sets and triode receivers. In early powered radios, the headphone was part of the vacuum tube's plate circuit and had dangerous voltages on it. It was normally connected directly to the positive high voltage battery terminal, and the other battery terminal was securely grounded. The use of bare electrical connections