The technology that enables connectivity of the device, e.g. wired or wireless.

Bluetooth is a low-power radio technology developed to replace the cables and wires currently used to link or connect electronic devices such as personal computers, printers, and a wide variety of handheld devices including mobile phones. Because it uses radio-wave connectivity, a Bluetooth-enabled device has a constant, established connection to whatever browser it uses. This saves the user the trouble of logging on to check for emails or news updates, for example.

Ear coupling describes the way in which headphones or earphones stay attached to, or inside, the ear. There are three common types of ear coupling: circumaural, supra-aural and intra-aural. Circumaural headphones enclose your ears with large pads that suppress external noise. Supra-aural headphones are typically more lightweight and sit on top of the ears with small pads. Intra-aural headphones come in two basic designs and neither style sits on the head itself. The first are ear buds, which sit just outside of the ear canal, on top of your ear lobes. The second type is actually inserted directly into the ear canal and offers some external noise suppression.

The range of frequencies (low to high sounds) that the headphones can produce.

The effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance.