Q13Q Traditional methods of protectin... [FREE SOLUTION]

Chapter 12: Q13Q (page 328)

Traditional methods of protecting the hearing of people who work in areas with very high noise levels have consisted mainly of efforts to block or reduce noise levels. With a relatively new technology, headphones are worn that do not block the ambient noise. Instead, a device is used which detects the noise, inverts it electronically, then feeds it to the headphones in addition to the ambient noise. How could adding more noise reduce the sound levels reaching the ears?

Short Answer

Expert verified

The opposite wave and the original wave are in destructive interference. The person with headphones receives a net signal of the opposite wave and original wave, and the net signal has very low intensity.

Step by step solution

Meaning of destructive interference

Destructive interference is considered a kind of interference in which the resulting wave's amplitude is smaller, and this kind of interference results in the development of the nodes. The nodes are the regions of zero displacements of the medium.

Explaination for how could adding more noise reduce the sound levels reaching the ears

Active noise suppression is based on the idea of destructive interference. If the ear is presented with a sound and, at the same time, an inverted copy of the sound produced by headphones, the two sound waves will cancel one another out, so very little will be heard. This technology works best on repetitive noises, like machinery noise, where the pattern is predictable. The anti-noise generator needs no calculator and generates an inverted sound in real-time but can do so based on what it heard a few cycles earlier.