This Standard is intended to specify the jack and plug wiring for proper polarization and channel reproduction. It is also intended to specify phones marking for left and right when they are marked. This Standard covers only headphones using a 3-contact plug similar to Figure 1. It does not apply as such to amplifier, tuner and other equipment using the jack, but these equipments must be wired correspondingly if phones are to reproduce left and right channel, with proper polarization, at corresponding left and right ear.