Digital high frequency phase compensation
DC
First Claim
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1. A method of implementing a high-frequency phase compensation transform in a signal processing pathway of a circuit providing active noise reduction (ANR) circuit in a first range of frequencies in a personal ANR device, the method comprising:
- programming a digital filter having at least one tap with at least one coefficient to cause the digital filter to employ the at least one tap to introduce at least one zero to introduce a positive phase in the pathway in at least the first range of frequencies; and
selecting the at least one coefficient to cause the addition of a gain that increases with frequency within a second range of audible frequencies outside of the first range of frequencies and that flattens in a range of frequencies above the second range of audible frequencies.
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Abstract
In an ANR circuit of a personal ANR device, a digital filter is structured to introduce one or more zeros to add gain to introduce positive phase in the provision of feedback-based ANR, wherein the gain follows a frequency-dependent “ski-slope” gain curve with little gain added at lower audible frequencies, with increasing gain that increases with frequency added at higher audible frequencies, and with the increasing gain flattening at frequencies above audible frequencies.
74 Citations
16 Claims
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1. A method of implementing a high-frequency phase compensation transform in a signal processing pathway of a circuit providing active noise reduction (ANR) circuit in a first range of frequencies in a personal ANR device, the method comprising:
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programming a digital filter having at least one tap with at least one coefficient to cause the digital filter to employ the at least one tap to introduce at least one zero to introduce a positive phase in the pathway in at least the first range of frequencies; and selecting the at least one coefficient to cause the addition of a gain that increases with frequency within a second range of audible frequencies outside of the first range of frequencies and that flattens in a range of frequencies above the second range of audible frequencies. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An active noise reduction (ANR) circuit structured to provide at least one of feedforward-based ANR and feedback-based ANR in a first range of frequencies, the ANR circuit comprising:
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at least a first digital filter positioned along a pathway defined in the ANR circuit and configured with at least a first coefficient to implement a first transform to generate digital data representing an anti-noise sound; at least a second digital filter positioned along the pathway and configured with at least a second coefficient to introduce at least one zero to implement a high-frequency phase compensation transform to introduce a positive phase in the pathway in at least the first range of frequencies, wherein; introducing the at least one zero adds gain increasing with frequency at least partly within a second range of audible frequencies outside of the first range of frequencies; and the gain flattens in a range of frequencies above the second range of audible frequencies. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A personal active noise reduction (ANR) device to provide at least one of feedforward-based ANR and feedback-based ANR to an ear of a user in a
first range of frequencies, the personal ANR device comprising: -
a casing defining a cavity to be acoustically coupled to an ear canal of an ear of the user at a time when the casing is in position adjacent the ear; an acoustic driver disposed within the casing to acoustically output anti-noise sounds into the cavity as part of the provision of the at least one of the feedforward-based ANR and the feedback-based ANR; an ANR circuit coupled to the acoustic driver to generate the anti-noise sounds from noise reference sounds to drive the acoustic driver with an analog signal to cause the acoustic driver to acoustically output the anti-noise sounds; at least one digital filter incorporated into the ANR circuit; and at least one tap incorporated into the digital filter and configured with at least one coefficient to introduce at least one zero to implement a high-frequency phase compensation transform to introduce a positive phase in the generation of the anti-noise sounds in at least the first range of frequencies, wherein; introducing the at least one zero adds gain increasing with frequency at least partly within a second range of audible frequencies outside of the first range of frequencies; and the gain flattens in a range of frequencies above the second range of audible frequencies. - View Dependent Claims (14, 15, 16)
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Specification
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Litigation Data
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Current AssigneeBose Corporation
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Original AssigneeBose Corporation
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InventorsCarreras, Ricardo F., Gauger, Daniel M. Jr., Isabelle, Steven H.
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Primary Examiner(s)Mei, Xu
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Assistant Examiner(s)TON, DAVID L
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Application NumberUS12/750,309Publication NumberTime in Patent Office1,008 DaysField of Search381/71.6, 381/71.11, 381/71.1, 381/71.14, 381/72, 381/73.1, 381/74, 381/97US Class Current381/71.6CPC Class CodesG10K 11/17823 Reference signals, e.g. amb...G10K 11/1783 handling or detecting of no...G10K 11/17833 by using a self-diagnostic ...G10K 11/17854 the filter being an adaptiv...G10K 11/17855 for improving speed or powe...G10K 11/17881 the reference signal being ...G10K 2210/3028 Filtering, e.g. Kalman filt...G10K 2210/3044 Phase shift, e.g. complex e...G10K 2210/3051 Sampling, e.g. variable rat...
