Impedance: Generally speaking, the lower the headphones' electrical impedance (aka resistance), the easier it is to get higher volume. But here again, the low impedance is no guarantee of high volume capability; other factors can still limit loudness potential. Since many MP3 players have feeble power output -- the iPod is a notable exception -- smart shoppers should check the loudness before purchasing any pair of headphones. To be sure, listen with your player.
Whether you wear headphones for your daily commute, regular workouts, or just for jamming out at home, you need a good pair that’s comfortable and can make everything sound great. Headphone tech has evolved significantly, too, so some pairs can do a lot more than just play sound. It’s not tough to find a pair that can connect to your smartphone wirelessly, or one that can keep outside commotion out.
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.