On-ear Headphones

Whether you take your music seriously or simply want to shut out the world when you need some peace and quiet, "noise-cancelling" headphones have become a popular product.
As the category name suggests, "noise-cancelling" headphones are designed to cancel out noise around you -- such as engine roar on an airplane when you're trying to catch some shuteye or a television murmur in another room of your home that's interrupting your classical music enjoyment.
These clever products look like regular headphones that go over or inside your ears, but can greatly reduce environmental noise up to a few metres around you.
Today I received a tweet (@marc_saltzman) from a Moneyville reader who asked me to explain the difference between "active" and "passive" noise-cancelling. It seems this reader was confused about the differences between the two as the weekly flyers from electronics retailers referenced both of them in the headphone section.
Active "noise-cancelling" headphones work by introducing inverse sound waves that negate incoming sounds, therefore dramatically reducing the amount of outside noise experienced by the listener. This is achieved by a tiny microphone that "hears" the noise and a processor that generates a sound wave with the opposite polarity to cancel it out, so to speak. Most of these headphones can block out more than 90 percent of all outside noise.
Active noise-cancellation requires battery power, however. Sometimes a rechargeable battery is included with the headphones, while in other instances you must buy an AA or AAA battery.
Most active headphones are the over-the-ear variety, but there are exceptions (such as this Sony pair worn in the photo).