Frequency response: Frequency-response specifications in full-size loudspeakers are generally pretty useless in predicting sound quality, but headphone frequency-response numbers are even worse. Manufacturers have routinely exaggerated frequency-response figures to the point that they're irrelevant. Even the flimsiest, cheap headphones routinely boast extremely low bass-response performance --15Hz or 20Hz -- but almost always sound lightweight and bright. Generally, bass buffs will be happier sticking with larger 'phones.
A planar magnetic driver consists of a relatively large membrane that contains an embedded wire pattern. This membrane is suspended between two sets of permanent, oppositely aligned, magnets. A current passed through the wires embedded in the membrane produces a magnetic field that reacts with the field of the permanent magnets to induce movement in the membrane, which produces sound.
Of the tested codecs we met, aptX and aptX HD fared the best out of all our candidates. While that may seem strange to say, on the whole their results were right where they needed to be in order to stand in for a wire for commuters, and listeners over 40. You’d really only run into issues at high volumes (90+dB), so while aptX isn’t quite able to keep up with CD quality, aptX HD is able to get extremely close to the mark with a little processing creativeness. Both codecs fall short in the highest frequencies a human could potentially hear, but the vast majority of people can’t hear sounds over 18kHz anyway.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.