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Hybrid feedforward-feedback active noise reduction for hearing protection and communication
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10.1121/1.2259790
/content/asa/journal/jasa/120/4/10.1121/1.2259790
http://aip.metastore.ingenta.com/content/asa/journal/jasa/120/4/10.1121/1.2259790

Figures

Image of FIG. 1.
FIG. 1.

Hybrid feedforward-feedback ANR topology.

Image of FIG. 2.
FIG. 2.

Open loop transfer function from an internally generated signal, through the cancellation speaker, to the error microphone. (a) Circumaural earcup on flat plate; (b) ANR earplug in flat plate, human ear, and two insertion depths in HEAD Acoustics manikin.

Image of FIG. 3.
FIG. 3.

Active attenuation performance of the ANR systems for circumaural earcup and (a) pure-tone noise, (b) F-16 cockpit noise, and (c) Huey helicopter noise.

Image of FIG. 4.
FIG. 4.

Comparison of the frequency response function of identified models with transfer function estimate from identification data.

Image of FIG. 5.
FIG. 5.

Comparison of identified cancellation path model frequency responses for two different deep insertions and one shallow insertion of the ANR earplug in the LFATC.

Image of FIG. 6.
FIG. 6.

ANR performance measured using the B&K microphones (solid) and the ANR microphones (dashed) for sum-of-tones in the LFATC evaluation.

Image of FIG. 7.
FIG. 7.

ANR performance with no communications signal present (solid) and with a communications signal present (dashed) for sum-of-tones in the LFATC evaluation.

Image of FIG. 8.
FIG. 8.

Total attenuation of sum-of-tones for hybrid ANR as measured by transmission loss between the B&K microphones in the LFATC.

Image of FIG. 9.
FIG. 9.

Sound level measured at unoccluded manikin ear and unmodified CEP occluded manikin ear for (a) sum of tones noise , (b) UH-60 cockpit noise.

Image of FIG. 10.
FIG. 10.

Sound level at unoccluded manikin ear and after hybrid ANR for ANR-modified CEP and (a) sum-of-tones , and (b) UH-60 cockpit noise. Performance is measured at both the manikin microphone and ANR microphones. Passive levels are provided for sum-of-tones.

Image of FIG. 11.
FIG. 11.

Total attenuation at error microphone with no communication signal present, and with a communication signal present. Total attenuation also reported at manikin ear microphone. (a) Sum-of-tones , (b) UH-60 cockpit noise.

Image of FIG. 12.
FIG. 12.

Ratio of maximum stable gain of the hybrid system and of the feedforward system alone when the feedback gain is set to provide a gain margin.

Tables

Generic image for table
TABLE I.

Overall C-weighted passive, active, and total noise reduction performance for feedback, feedforward, and hybrid ANR in earcup testing within a low frequency acoustic test cell.

Generic image for table
TABLE II.

Overall C-weighted total attenuation of sum-of-tones and UH-60 cockpit noise in the band, both at source levels.

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/content/asa/journal/jasa/120/4/10.1121/1.2259790
2006-10-01
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Hybrid feedforward-feedback active noise reduction for hearing protection and communication
http://aip.metastore.ingenta.com/content/asa/journal/jasa/120/4/10.1121/1.2259790
10.1121/1.2259790
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