The impedance of earphones is the abbreviation of their AC impedance, which refers to the blocking effect on AC power in circuits with resistors, inductors, and capacitors. The unit of impedance is ohm (Ω). In general, the smaller the impedance, the easier it is for the earphone to sound and drive.
The impedance of a headset is short for its AC impedance, and its size is the sum of the coil DC resistance and the coil inductance: Z=(R2+02L2) 1/2. The impedance of both civil and professional earphones is generally below 100 Ω, while some professional earphones have impedance above 200 Ω. This is to reduce the load of a power amplifier when it pushes multiple earphones. Headphones with high driving impedance require more power.
