An apparatus for noise cancellation of ambient noise impinging upon the front surface of a pressure differential microphone on the end of a boom. The apparatus utilizes curved reflectors to cause ambient noise which impinges on the front surface of the microphone to also impinge on the back surface of...http://www.google.de/patents/US6009184?utm_source=gb-gplus-sharePatent US6009184 - Noise control device for a boom mounted noise-canceling microphone
