ACTIVE NOISE CONTROL METHOD & APPARATUS UTILIZING CHANNEL DIFFERENCE OF NOISE TRANSMISSION PIPE

摘要

The pipe (1) has a pipe (2) whose length can be variable and a pipe (3) of a fixed length. The frequency difference between the variable pipe (2) and the fixed pipe (3) is produced for half or half plus harmonies of the wave length to be reduced a controller (4) when the noises of two pipes are united into one. The noise of the outlet part of the pipe (1) is sent to the controller by a mike (7).