And the smoking gun -

''A first area of improvement is in the microphone input. Specifically, there are now provided a primary microphone 50 and a noise canceling microphone 52. In other words, the noise canceling microphone 52 is able to provide a signal which is useful in canceling noise received by the primary microphone 50, using techniques which are well known to those skilled in the art. It is important to realize that this function is desirable when recording a voice as opposed to the situation when music is being recorded. Accuracy in recording music is a very distinct process from accurately recording a voice. For example, it is not as important that a voice being played back sound as close as possible to the actual voice which was recorded. What is important is that the voice be distinct and distinguishable from distracting or interfering noise in the background. Consequently, accuracy in reproducing the recorded voice is advantageously sacrificed for clarity.''

hmmmm

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