1.has passive noise reduction
The device sits tightly in place, creating an acoustic seal which reduces background noise and prevents your music from leaking out.
The highest frequency at which device produces audio. The higher the high-frequency response, the clearer and crispier the treble.
The lowest frequency at which the device produces audio. The lower the low-frequency response, the stronger and juicier the bass.
Impedance is the device’s electrical resistance to the current being pushed through it. The lower the impedance, the easier it is to get higher volume and requires less power.
The driver unit is the component that produces sound in the device. Bigger drivers are more powerful and can produce better bass.
Devices with a higher sound pressure level are generally louder when supplied with any given audio source.