Have you ever found yourself turning your music up really loud because even though you’re wearing headphones, the ambient noise around you keeps drowning out your tunes? It’s especially annoying when you’re in an environment such as a plane or a train because there is no escape from the volume of the engines or the people around you. Even though you have your ears completely covered and some noise is reduced, the ambient noise still permeates. That’s where noise-cancelling headphones can help you still enjoy your music even in these difficult and noisy environments. Noise-cancelling headphones are made as either active or passive.

Passive noise-cancelling headphones are specially constructed with layers of high-density foam or other sound-absorbing material which can make them heavier than normal headphones. The benefit of the extra weight is the reduction of noise by about 15 to 20 decibels (dB) which is great for significantly reducing ambient noise in regular situations. Although this is an excellent reduction, considering that a jet engine produces about 80dB of noise inside the plane, there will still be some serious permeation issues in extremely noisy situations.

Active noise-cancelling headphones can do all of the above, but they have an extra feature which actively erases lower-frequency soundwaves. To achieve this, they are designed to create their own soundwaves which reproduce the incoming ambient noise and express them 180 degrees out of phase with the incoming waves. The two alternate waves (see diagram) one comes from the headphones, the other is the ambient noise externally are essentially the same amplitude and frequency, however their peaks and troughs are arranged so that the peaks of one wave will line up with the troughs of the other wave. Essentially this means that the two waves cancel each other out. This means that you are able to hear more of the real sound you want. A good set of active noise-cancelling headphones can reduce noise by about 80dB, which can give the listener a much cleaner sound.

Available at Selby:

Sennheiser PXC150 Travel Headphones
The Sennheiser PXC150 are closed supra-aural mini headphones with “NoiseGard” active noise compensation.

Features:
- Dynamic stereo mini headphones
- Ideal for mobile audio sources such as MP3 players or portable CD players
- Includes convenient draw string pouch
- Ideal for storing: the ear cups can be turned through 90°
- Soft ring ear pads ensure excellent passive attenuation of ambient noise
- Switchable “NoiseGard” active noise compensation ideal for use on planes

- In-line “NoiseGard” box (for 2 AAA batteries), can be rotated through 360°
- Transparent and lifelike audio reproduction due to Sennheiser "Duofol" diaphragms with spiral embossing
- Computer-optimised neodymium magnets for extremely low distortion
- Bass tube for crisp, powerful bass
- Included adaptors: 1/4" (6.3mm) stereo jack and 3.5mm double mono jack
- Lightweight (only 65 g without cable)  

House of Marley Trenchtown Rock Iron Ear Headphones

With ultra-soft leather ear cups and sound isolating technology, these premium noise-canceling headphones remove unwanted outside noise.
Over-ear design for exceptional comfort even during long listening sessions. 12Hz - 23kHz frequency response adds clear sound reproduction. And a 40-millimeter dynamic moving coil speaker drive for sound reinforcement.

Ultimate Comfort
Lightweight padded headset made from recyclable aluminum and soft leather.

Gold Plated Connector
Right-angled, 3.5-millimeter gold-plated connector designed to fit with a variety of device cases and create a high-quality connection for sound.

Fabric Covered Cord
52" fabric cord helps reduce tangles and is specially engineered to cut down on static so you get that clear sound.

1 Button Mic
The headphone’s cable features an inline ‘1 Buttom Mic’ microphone to take calls on the go or check with Siri on your pace. Simply click the button to change the tune.The gold-plated 3.5mm headphone plug provides compatibility with a variety of MP3 players, CD players, laptops and other devices.*

Also included is a travel bag for convenient storage and transportation.

Earth-Friendly Materials
Designed and built with FSC certified sapele and beech wood and recyclable aluminum.
Recyclable aluminum ring that’s high quality, adds to durability and keeps materials out of the waste stream. Packaging is also made from pulp, recycled plastics and recycled paper, and less of them, to cut down on what goes in the waste stream.