| There are basically two types of headphones created | | | | loudness and pitch of the noise. The circuitry then |
| to reduce background noise. Passive noise cancelling | | | | creates an exact replica of the noise and throws it 180 |
| headphones and active noise canceling headphones. | | | | degrees out-of-phase. This, for all intents and purposes, |
| The passive type muffles extraneous sounds while | | | | eliminates the sound. |
| the active ones electronically decrease external noise. | | | | The headphone speaker then plays this "non-sound" |
| Passive | | | | along with whatever it is that you are listening to. This |
| Passive noise cancelling headsets use what is known | | | | artificial noise is the exact opposite of the extraneous |
| as circum-aural sound dampening design. They are | | | | noise that makes it past the ear cushions. They then |
| shaped like a cup, which surrounds the ear. The rim of | | | | cancel each other out due to the 180-degree phase |
| this cup is made of a high-density foam and sound | | | | reversal. As a result the external noise is reduced |
| wave dampening material. This creates a seal that | | | | significantly, allowing you to enjoy your audio with a |
| blocks up to 20 dB of noise. | | | | dramatic decrease in background noise. |
| Active | | | | These types of headphones are ideal for airplanes or |
| The active noise cancellation headphones produce an | | | | any place where there is a lot of external noise. On |
| additional 20dB of noise reduction than the passive | | | | airplanes, for example, this type of noise reduction |
| type. It employs the same technology (circum-aural | | | | while using headphones will dramatically reduce fatigue. |
| sound dampening design) as the passive headphones | | | | Another difference between the two is that the active |
| but also incorporates phase cancellation. This is the | | | | type requires a power source, usually a battery. |
| key feature of active noise cancelling headphones. A | | | | Noise cancelling headphones tend to be larger and |
| microphone is placed inside the headphone that picks | | | | heavier that regular headsets or earphones. They can, |
| up external noise that the aural cushions of the | | | | however, be more comfortable when worn for long |
| passive headphones are unable to block out. The | | | | periods of time due to the large cushions that impose |
| phase cancelling technology is able to analyze the | | | | less pressure on the ears. |
| intensity and frequency of the pitch, also known as the | | | | |