The earphone sensitivity points to the sound pressure level that the earphone can emit when the earphone inputs 1 milliwatt of power (the unit of sound pressure is decibels, the greater the sound pressure, the greater the volume), so generally the higher the sensitivity and the lower the impedance, the easier the earphone is Sound, the easier it is to drive.
Generally speaking, the sensitivity of the earphone is actually the sensitivity level of the earphone. It is the sound pressure level generated by the earphone coupled to the artificial ear (dummy head) when the electric power of 1mW is applied to the earphone. The power of 1mW is the frequency The standard impedance of the earphone at 1000 Hz is calculated based on it. The unit of sensitivity is dB/mW, and another uncommon one is dB/Vrms, which is the sound pressure level generated when a voltage of 1Vrms is applied to the earphone. High sensitivity means that the power required to reach a certain sound pressure level is small. Nowadays, the sensitivity of moving coil earphones is generally above 90dB/mW. If you choose earphones for walkmans, the sensitivity should be around 100dB/mW or higher. .