David Clark Company

How Does Electronic Noise Cancellation Work?

ENC Waves Example
David Clark Company Electronic Noise Cancellation (ENC) ‘X-Series’ headsets feature the latest advances in active noise reduction technology. Our ENC headsets are specially designed for pilots of aircraft which generate noise at lower frequencies. Active reduction of unwanted noise is achieved by a process which amounts to cancellation of the noise by generating a signal identical in sound pressure level (SPL) but exactly reversed in phase to the offending noise ; the effect being a cancellation (see fig.1).

Electronic Noise Cancelling is accomplished in the following manner:

A miniature microphone is placed in the ear cup next to the earphone element and as near as possible to the entrance of the ear canal. This microphone senses the noise as it enters the ear. The signal developed by the sensing microphone represents noise which has penetrated the passive attenuation barrier, and is composed of predominantly low frequencies. This signal is fed to a circuit where it is inverted in phase, amplified, and then drives an earphone creating an anti-noise signal which cancels the intruding noise. This is a type of feedback control system (see fig.2).

ENC Diagram

An important feature of the product, exclusive to our design, is true "fail-safe" operation. By having dual earphone drivers, which are electronically independent, no interruption of communication can result from failure of the ENC system or its power source.

Our ENC Headset System is manufactured to the same high standards as our conventional headsets. Superior passive attenuation is combined with state of the art electronic noise cancellation in a product providing exceptional communication clarity.