Patent ID: 8315405
Filing Date: 2012-11-20
Classification: G10K,G10L,H03G,H04R

Abstract:
1. An active noise reducing (ANR) circuit comprising: a first Variable Gain Amplifier (VGA) to compress a feedforward reference sound represented by a signal output by a feedforward microphone detecting an external noise sound in an environment external to a casing as the feedforward reference sound; a second VGA to compress a feedback reference sound represented by a signal output by a feedback microphone detecting a cavity noise sound within a cavity defined by the casing as the feedback reference sound; at least one filter to generate a feedforward anti-noise sound from the feedforward reference sound; at least another filter to generate a feedback anti-noise sound from the feedback reference sound; and a compression controller coupled to the first and second VGAs to operate the first and second VGAs to coordinate compression of the feedforward and feedback reference sounds in response to the acoustic energy of the external noise sound reaching a first threshold; wherein the compression controller is structured to operate the first VGA to compress the feedforward reference sound to an increasingly greater degree than the compression controller operates the second VGA to compress the feedback reference sound as the acoustic energy of the external noise sound rises further above the first threshold.