Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Subband Beamforming for Speech Enhancement in Hands-Free Communication
Responsible organisation
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Speech enhancement by means of microphone array signal processing has a major role in voice communication applications such as audio-conferencing, hands-free telephony, voice recognition and hearing aids. In these communication scenarios, the speaker is positioned at a remote distance from the microphones, which causes problems of environment noise and interfering sound corrupting the received speech. Additionally, reverberations of the voice from walls or ceilings, also impairs the received speech signal. In the case of a duplex communication, the acoustic feedback constitutes another disturbance for the talker who hears his or her voice echoed. Successful speech enhancement solutions should achieve speech dereverberation, efficient noise and interference reduction, and for mobile environments, they should also provide an adaptation capacity to speaker motion. Microphone arrays spatially sample the sound pressure field. When combined with spatio-temporal filtering techniques known as {\em beamforming}, they can extract the sound source information from signals, of which only a mixture is observed. This is based on the inherent ability of sensor arrays to exploit the spatial correlation of multiple received signals. A subband beamforming structure can be used in order to improve the performance of the time-domain filters and reduce their computational complexity. Each of the received signals is decomposed into a set of narrow-band signals and the filtering operations of the beamformer are performed for each frequency band separately. The output of the subband beamformers are then used to reconstruct a full-band output signal. In this thesis an adaptive subband RLS beamforming approach is investigated and evaluated in real hands-free acoustical environments. The proposed methodology is defined such to perform background noise and acoustic coupling reduction, while producing an undistorted filtered version of the signal originating from a desired location. The beamformer recursively minimizes a Least Squares error based on the continuously received data. This adaptive structure allows for a tracking of the noise characteristics, such to accomplish its attenuation in an efficient manner. A soft constraint built from calibration data in low noise conditions guarantee the integrity of the desired signal without the need of any speech detection. Additionally, a new spatial filter bank design method for beamforming applications, which includes the constraint of signal passage at one position and closing in other undesired positions, is suggested. Furthermore, to allow for source mobility tracking, a soft constrained beamforming approach with built-in speaker localization, is proposed. The source of interest is modelled as a cluster of point sources and source motion is accommodated by revising the point source cluster. Real speech signals are used in the simulations and results show accurate speaker movement tractability with maintained noise and interference suppression of about 10-15 dB, when using a four-microphone array.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Institute of Technology , 2004. , p. 135
Series
Blekinge Institute of Technology Licentiate Dissertation Series, ISSN 1650-2140 ; 13
Keywords [en]
Beamforming, Speech enhancement, Subband filtering
National Category
Signal Processing
Identifiers
URN: urn:nbn:se:bth-00267Local ID: oai:bth.se:forskinfo1B3E05CFDDC3D6ACC1256FB80053AEA1ISBN: 91-7295-053-6 (print)OAI: oai:DiVA.org:bth-00267DiVA, id: diva2:838313
Available from: 2012-09-18 Created: 2005-03-02 Last updated: 2015-06-30Bibliographically approved

Open Access in DiVA

fulltext(722 kB)1047 downloads
File information
File name FULLTEXT01.pdfFile size 722 kBChecksum SHA-512
8c6777ff61830a763c5ad8f10fe4758dee2abc5cecac100c4783f736924c4f532edd3480b5e30c5b54cf58f3665bbcc33a46d326e19fc63cae54cbe55e0b68b2
Type fulltextMimetype application/pdf

Signal Processing

Search outside of DiVA

GoogleGoogle Scholar
Total: 1047 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 210 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf