Feedforward active noise reduction for aircraft headsets

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dc.contributor.advisorLourens, J. G.
dc.contributor.authorSmith, Corne J.
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.en_ZA
dc.date.accessioned2012-08-27T11:33:05Z
dc.date.available2012-08-27T11:33:05Z
dc.date.issued2003-12
dc.descriptionThesis (MScEng)--University of Stellenbosch, 2003.en_ZA
dc.description.abstractENGLISH ABSTRACT: Active noise reduction (ANR) is a method of cancelling acoustic noise in a defined enclosure. Two methods exist to implement ANR, they are the analog feedback method and the digital feedforward method. Commercial ANR systems employing feedback methods have been around since the 1980's. Feedforward methods have however only become practically implemental with the age of fast real time digital signal processing. In current systems, feedback ANR is used to attenuate broadband noise whilst feedforward methods are used to attenuate narrow band or tonal noise [2]. This thesis investigates feedforward ANR to cancel broadband acoustic noise in aircraft headsets. Different adaptive filters, optimal configuration of adaptive filters and practical limitations to broadband attenuation for headsets are addressed. Results from this thesis show that at least 10dS noise energy attenuation is attainable over a bandwidth of 2.5kHz. A number of areas for further research are also identified.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Aktiewe geraas beheer (AGS) is 'n metode om akoestiese geraas te kanselleer in 'n gedefinieerde omgewing. Twee metodes bestaan om AGS te implementeer. Hulle is die analoog terugvoer en digitale vorentoevoer metode. Kommersiële AGS wat die terugvoer metode gebruik is al in gebruik van die 1980's. Vorentoevoer metodes is egter eers sedert vinnige intydse digitale sein prosessering moontlik. In huidige stelsels word terugvoer AGS gebruik vir die attenuasie van wyeband geraas terwyl vorentoevoer metodes gebruik word om nouband of enkel toon geraas te kanselleer [2]. Die tesis ondersoek vorentoevoer AGS om wyeband akoestiese geraas te kanselleer in vliegtuig kopstukke. Verskillende aanpasbare filters, optimale opstelling van aanpasbare filters en praktiese beperkings tot wyeband attenuasie vir kopstukke word ondersoek. Resultate van die tesis wys dat ten minste 10dS geraas energie attenuasie behaal kan word oor 'n bandwydte van 2.5kHz. 'n Aantal areas vir verder navorsing is ook geïdentifiseer.af_ZA
dc.format.extent1 v. (various foliations) : ill.
dc.identifier.urihttp://hdl.handle.net/10019.1/49761
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectNoise controlen_ZA
dc.subjectElectronic circuits -- Noiseen_ZA
dc.subjectDissertations -- Electronic engineeringen_ZA
dc.subjectTheses -- Electronic engineeringen_ZA
dc.titleFeedforward active noise reduction for aircraft headsetsen_ZA
dc.typeThesisen_ZA
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