Dynamically Configurable ANR Filter Block Topology

摘要

An active noise reduction (ANR) circuit includes a digital feed-forward ANR pathway coupled to a feed-forward microphone, to detect environmental sounds in an environment external to a casing, and to a first acoustic driver to output sounds within the casing. The digital feed-forward ANR pathway applies a plurality of filters using a first set of coefficients to convert signals from the feed-forward microphone to feed-forward anti-noise sounds to reduce environmental sounds within the casing. In response to a stimulus, the digital feed-forward ANR pathway applies the plurality of filters using a second set of coefficients, which reduce the degree of feed-forward ANR to enable human speech sounds in the environment external to the casing to be conveyed from the feed-forward microphone to the acoustic driver with less reduction than provided by the first plurality of filters.

主权项

1. An apparatus for providing active noise reduction (ANR), the apparatus comprising:
a first ADC, a second ADC, a DAC; and a dynamically configurable digital signal processor (DSP) configured to: incorporate the first ADC, a first plurality of digital filters of a quantity and type specified by a first set of ANR settings, and the DAC into a first pathway; incorporate the second ADC, a second plurality of digital filters of a quantity and type specified by the first set of ANR settings, and the DAC into a second pathway; configure interconnections among the elements of the first and second pathways so that digital data from the first and second pathways are combined before flowing to the DAC; operate each of the digital filters using filter coefficients specified by the first set of ANR settings; transfer digital data through at least a portion of at least one of the first and second pathways at a data transfer rate specified by the first ANR settings; operate the first and second pathways to provide ANR; and change a parameter specified by the first set of ANR settings to a parameter specified by a second set of ANR settings in synchronization with a transfer of digital data along at least a portion of at least one of the first and second pathways.