A cellular telephone for reducing background noise comprising a housing having a receiver portion and a speaker portion; the receiver portion having a voice port and a noise port; a microphone isolator located within the receiver portion; at least one noise canceling microphone having a front end and...http://www.google.de/patents/US6108415?utm_source=gb-gplus-sharePatent US6108415 - Noise cancelling acoustical improvement to a communications device
