The lowest frequency at which the device produces audio. The lower the low-frequency response, the stronger and juicier the bass.
2.Has sound isolation / passive noise reduction
vs No (51% don't have it)
The device sits tightly in place, creating an acoustic seal which reduces background noise and prevents your music from leaking out.
3.Has an in-line control panel
vs No (56% don't have it)
There is a control panel on the cable, so you can easily operate the device without having to interact with it.
4.A lot more microphone(s)
vs 1 (the average)
vs 8 (best: Parrot Zik Sport)
More microphones result in better sound quality and enable the device to filter out background noise.
5.Has an in-ear form
vs No (67% don't have it)
The in-ear device is ultracompact and lightweight, with little or no interference with earrings, spectacles, hats, or hairstyles. It is inserted in the ear canal itself and blocks out a lot of environmental noise. It has stronger bass tones and is unlikely to fall out of the ear.