Sealing the ear canal blocks background noise before it reaches the ear

Evidence

Passive noise cancellation can be achieved with in-ear earphones that seal well in the ear canal. The principle here is to block the ear canal to reduce the level of acoustic background noise that enters the ear canal using the same technique used for in-ear ear defenders. Usually there are a number (two or three) of soft rubber flanges that form a seal with the border of the ear canal to attenuate the level of acoustic background noise that can enter the ear. The wanted sound is played via the earphones, which are mounted in the body of the earphones, and the level of the wanted sound can be reduced as with active noise cancelation. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2566

Categorization

• DEFINE: Explains passive noise cancellation and its sealing principle.