The headphone port is primarily used to connect headphones. The standard 1/4-inch (6.35mm) diameter headphone plug and jack is designed from the early telephone patch panels, and this terminal is generally a three-wire structure (divided into one for each left/right channel and a ground) for stereo signal output on AV equipment. Headphone plug and jack is also usually used for professional or broadcast equipment, this time is a two-wire structure (divided into signal and ground) for the transmission of mono signals; sometimes also use a three-wire structure (divided into positive, negative and shielding) to balance the transmission of mono signals. The 1/8-inch diameter (3.5mm) small headphone jacks are common on Walkmans, and are functionally the same as the standard headphone jacks, which are used on portable devices for stereo signal transmission.
1, moving coil type:
Dynamic headphones is the most common, the most common headphones, its driver unit is basically a small moving coil speaker, by the voice coil in the permanent magnetic field to drive the diaphragm vibration connected to it. Moving coil headphones are more efficient, most can be driven for the headphone output on the stereo, and reliable and durable.
2, coil-iron hybrid:
Coil headphones is a moving coil moving iron hybrid drive sound headphones, single moving coil + single moving iron, single moving coil + double moving iron structure, the advantages of the moving iron unit lies in the electro-acoustic conversion efficiency is high, the vibration of the body is light, so the sensitivity is high, the transient performance is good, so that the original moving coil is difficult to perform the music dynamics, instantaneous details stand out.
Low frequency and mid-frequency by the moving coil unit naturally rendering, play moving coil low-frequency extension and mid-frequency fullness, the transition of natural advantages. The moving iron unit's advantage and role is mainly to undertake and complement the moving coil high-frequency attenuation section, starting from the 6kHz crossover point, the moving iron unit is responsible for the high frequency, the high-frequency range will be extended to 30kHz. Expanded Information:
Precautions for Using Headphones:
Because headphones are closer to the inner ear tissues than ordinary external noise; users have to take the necessary protective measures. Studies have shown that pleasant music causes less hearing damage, but prolonged exposure to high decibel sounds, whether music or noise, can cause hearing damage. Sensory nerve hearing damage that can be triggered by noise occurs in the inner ear when high-energy sound waves soup up the fluid in the cochlea, overstimulating and causing cell death. Hearing damage occurs over time, and prolonged exposure to noise, albeit for short periods at a time, can cause hearing loss.
A survey published in the Journal of the American Medical Association in 1998 and experiments at Shanxi Medical University in China showed that prolonged exposure to high noise levels had a negative effect on hearing.
When using headphones on the street, in addition to turning up the volume and causing hearing damage, focusing on listening to music can easily make the user lose awareness of peripheral sounds, increasing the chances of danger, and children should not use them.
Baidu Encyclopedia - Headphones
Baidu Encyclopedia - Headphone Ports