Noise Cancelling versus Noise Reduction - The Difference When It Comes to Headphones

Noise-cancelling headphones use tiny microphones that identify
the noise or sounds outside the headphones and then work to
cancel out the sounds. Noise-reduction headphones (also known as
noise-isolation headphones) reduce sound by being a barrier
through which sounds cannot pass. What does all this mean? And
how do these two differ?

Wikipedia (www.wikipedia.org) states, "noise cancelling is a
method for preventing unwanted sound. Sound consists of
vibrations in the air, which can be represented as a wave. If a
speaker emits a sound whose wave has the same amplitude and the
exact opposite polarity to the original sound, the waves cancel
out and the result is no sound at all."

While this seems rather technical here is a more simple
explanation: sound waves are created by the noise cancelling
headphones to counter and eliminate the unwanted sound waves
outside of the headphones or speakers. A digital signal
processor determines what sound wave is needed to cancel the
outside sound wave and it produces that sound and amplifies it
through the headphones.

This method differs from noise-reduction headphones which are
designed to reduce the noise you hear by physically blocking the
sound from reaching your eardrum. This is the same passive,
unpowered method that is used by insulation or sound-absorbing
ceiling tiles in your home.

Noise canceling headphones tend to work best for constant sounds
like lawn mowers and appliances but they allow in intermittent
sounds, such as conversation or a ringing phone, so you are not
totally isolated. They are also known to be more comfortable
than noise-reduction headphones since they are lighter weight
and generally smaller in size than noise-reduction headphones.

Some of advantages of noise cancelling methods compared to
noise-reduction methods are: *	They can be more effective at low
frequencies *	They can be less bulky *	They can be selective in
that they can block noise (e.g. from an engine) but not useful
sounds (e.g. voices).

Some of disadvantages of noise cancelling methods compared to
noise-reduction methods are: *	They consume power, usually
supplied by batteries that must be replaced. If the batteries
die the noise cancellation stops working; and if you are using
the headphones to listen to music, in many models, the music
stops as well. *	They may introduce additional noise, usually in
the form of high-frequency hiss. Noise cancellation headphones
attempt to block sound by sampling the outside sound and then
producing an equal but opposite sound - sometimes the
approximation of sound can be difficult.

Whatever method of noise reduction you choose, it can help
prevent hearing loss. By using headphones when listening to
music, you can hear the music at much lower volumes because you
are not trying to drown out background sounds. And those around
you won't have to listen to your music; it can be contained in
the headphones.