Bose Corporation

Other

Marcel Joho

Ricardo Federico Carreras

Daniel M Gauger, Jr

Benjamin Douglass Burge

Steven H Isabelle

Daniel M Gauger

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.

Dynamically configurable ANR filter block topology

Frequency-dependent ANR reference sound compression

Apparatus and method for implementing a convertible filter in differing ones of its delay and weighting elements are powered through different power conductors, thereby enabling the convertible filter to be dynamically configured to be operable as different types of digital filter through selective provision of power to differing ones of the power conductors.

Convertible filter

In a personal ANR device having a pair of earpieces, each having a feedforward microphone and an ANR circuit associated therewith, each ANR circuit provides digital data representing environmental noise sounds detected by each ANR circuit's associated feedforward microphone. Such digital data may represent the environmental noise sounds as detected with little or not modification, or such digital data may be modified to some degree within each ANR circuit, perhaps to limit the range of frequencies that such digital data represents, before being provided to the other ANR circuit.

Binaural feedforward-based ANR

An ANR circuit, possibly of a personal ANR device, monitors a sound level of environmental sounds detected by a microphone external to an earpiece in which the ANR circuit is providing feedback-based ANR, and increases or decreases the degree of feedback-based ANR provided in response to the external microphone detecting a higher or lower sound level, respectively. Increasing and decreasing the degree of feedback-based ANR provided may be carried out by changing a variable loop gain of the ANR circuit and/or a range of frequencies of environmental sounds attenuated by the feedback-based ANR.

Feedback-based ANR adjustment responsive to environmental noise levels

An ANR circuit, possibly of a personal ANR device, incorporates an signal processing topology to support the provision of feedback-based ANR, feedforward-based ANR and pass-through audio in which the topology incorporates a branch in which feedback anti-noise sounds are generated from feedback reference sounds received from a feedback microphone, a branch in which feedforward anti-noise sounds are generated from feedforward reference sounds, and a branch in which modified pass-through audio sounds are generated from pass-through audio sounds received from an audio source, wherein these three branches are combined to combine the generated sounds of each branch into a single output by which an acoustic driver, possibly of the personal ANR device, is driven.

ANR signal processing topology

An ANR circuit, possibly of a personal ANR device, reduces the degree of feedforward-based ANR that it provides in response to receiving an indication of the operation of a manually-operable control. The reduction of degree of feedforward-based ANR may be effected by turning off or otherwise deactivating the provision of feedforward-based ANR, reducing a range of frequencies of environmental noise sounds attenuated by the feedforward-based ANR to provide less attenuation of sounds detected by a feedforward microphone that are in a range of frequencies deemed to be those of human speech, and/or creating a notch in the range of frequencies of environmental noise sounds attenuated by the feedforward-based ANR to provide less attenuation of sounds detected by the feedforward microphone that are in a range of frequencies deemed to be those of human speech.

Feedforward-based ANR talk-through

At initialization of an ANR circuit (i.e., at so-called boot time), attempts are made to alternately obtain ANR settings from an external storage device by operating the ANR circuit as a master of a bus and from an external processing device by operating the ANR circuit as a slave of the bus. Such alternating attempts may be repeated until the ANR settings are loaded.

ANR settings boot loading

An ANR circuit, possibly of a personal ANR device and possibly within an ADC of the ANR circuit, feedback reference data, feedforward reference data and/or pass-through audio data is provided to a secondary downsampling (and/or decimating) filter and/or is provided to a calculating block (e.g., RMS or absolute calculation block) to derive side-chain data to be output by the ANR circuit to a processing device coupled to the ANR circuit to employ the side-chain data in an analysis related to the provision of feedback-based ANR, feedforward-based ANR and/or pass-through audio by the ANR circuit.

ANR analysis side-chain data support

In an ANR circuit, possibly of a personal ANR device, each of a feedback ANR pathway in which feedback anti-noise sounds are generated from feedback reference sounds, a feedforward ANR pathway in which feedforward anti-noise sounds are generated from feedforward reference sounds, and a pass-through audio pathway in which modified pass-through audio sounds are generated from received pass-through audio sounds incorporate at least a block of filters to perform those functions; and may each incorporate one or more VGAs and/or summing nodes. For each of these pathways, ANR settings for selections of quantities and types of filters for each filter block, bit sizes of coefficients and/or coefficient values of each of the filters, along with still other ANR settings, are dynamically configurable wherein dynamic configuration is performed in synchronization with the transfer of one or more pieces of digital data along one or more of the pathways, at least within one or more of the filter blocks.

In an ANR circuit, possibly of a personal ANR device, each of a feedback ANR pathway in which feedback anti-noise sounds are generated from feedback reference sounds, a feedforward ANR pathway in which feedforward anti-noise sounds are generated from feedforward reference sounds, and a pass-through audio pathway in which modified pass-through audio sounds are generated from received pass-through audio sounds incorporate at least a block of filters to perform those functions; and may each incorporate one or more VGAs and/or summing nodes. For each of these pathways, ANR settings for interconnections of each of the pathways, coefficients of each of the filters, gain settings of any VGA, along with still other ANR settings, are dynamically configurable wherein dynamic configuration is performed in synchronization with the transfer of one or more pieces of digital data along one or more of the pathways.

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Framingham, MA, United States of America

Marcel Joho