Noise canceling headphones reduce ambient noise so the wearer can either enjoy a greater degree of quiet for relaxation, or listen to music at lower volumes than would otherwise be necessary. By removing competing noises from the acoustic envelope, noise canceling headphones create a more pleasurable listening experience.

High frequencies in the immediate environment can be blocked to a great degree by using dense materials in the construction of the earcups. This is referred to as passive noise canceling (PNC) and is especially effective in models with larger ear cups. The drawback is that PNC does not lend itself to lightweight headphones or to in-ear earbuds that sit in the open end of the ear canal. In-canal earbuds, however, slide snugly into the ear and more effectively block high frequency noise.

To block lower frequencies, noise canceling headphones employ on-board electronics that continually sample ambient noise and generate inverse sound waves through the ear cup to exactly cancel the ambient fingerprint. To accomplish this, a small microphone built into the ear cup feeds surrounding noise to the electronics, which generates an opposite wave form, sending it through the earcups. This is referred to as active noise canceling (ANC) and requires power via a rechargeable battery.

The most effective noise canceling headphones employ both ANC to cancel high frequencies and PNC to cancel low frequencies. Examples of the latter might be the hum of a refrigerator motor, A/C unit, subway, or airline’s engines. In the latter case, it was on an airliner that Amar Bose, founder of Bose Corporation, first conceived of noise canceling headphones, as the plane’s engines drowned out the airline headphones. His ingenious idea was soon followed by others, and today there is no shortage of models to choose from.

As with any other technology, ANC and PNC have their limitations. PNC works best on reducing background noises that are consistent, rather than the constantly changing noises of nearby chatter or the cacophony of general hustle and bustle. Also, if you find in-canal earbuds uncomfortable and prefer lightweight earcups, effective noise canceling headphones might be a bit pricey. Generally, it’s cheaper and easier to build a bulkier, heavier cup.

All things considered, noise canceling headphones are a lifesaver in the right situations. Whether you’d like to block the drone of the neighbor’s gardening equipment to take a well deserved nap, or listen to your favorite soft music on that extended coast-to-coast flight, noise canceling headphones could be the answer you’ve been searching for. Before purchasing consider reading customer reviews from online retailers to get the scoop on which models represent the best value.