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Bahne, Adrian
Publications (9 of 9) Show all publications
Bahne, A. & Ahlén, A. (2016). Optimizing the similarity of loudspeaker: Room responses in multiple listening positions. IEEE Transactions on Audio, Speech, and Language Processing, 24(2), 340-353.
Open this publication in new window or tab >>Optimizing the similarity of loudspeaker: Room responses in multiple listening positions
2016 (English)In: IEEE Transactions on Audio, Speech, and Language Processing, ISSN 1558-7916, E-ISSN 1558-7924, Vol. 24, no 2, 340-353 p.Article in journal (Refereed) Published
Abstract [en]

A shortcoming of multichannel sound reproduction standards, such as stereo or 5.1 surround, is their incompatibility with multiple off-axis listening positions. Accurate reproduction of virtual sound sources can only be experienced in the sweet spot, which is located equidistant to the loudspeakers. We here present a novel methodology to compensate audio systems such that the channel similarity is optimized in several listening positions simultaneously. To that end we propose a novel MIMO personal audio filter design framework based on feed-forward control. By proper design choices, filters that successfully compensate for multiple offaxis positions and irregularities in the frequency sum responses are obtained. The design choices include allpass filters with appropriate phase shifts as target for each listening position in addition to a weighted similarity requirement. Evaluations based on measurements of two four-channel car audio systems show that the proposed method significantly improves timbral sound reproduction and phantom center reproduction in several listening positions simultaneously.

Keyword
Acoustic signal processing; audio systems; equalizers; loudspeakers; multiple sweet spots; psychoacoustics; virtual center
National Category
Engineering and Technology
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-267311 (URN)10.1109/TASLP.2015.2496156 (DOI)000367950900007 ()
Funder
Knut and Alice Wallenberg Foundation, KAW 2006.0152
Available from: 2015-11-20 Created: 2015-11-20 Last updated: 2017-12-01Bibliographically approved
Bahne, A. (2014). Multichannel Audio Signal Processing: Room Correction and Sound Perception. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis.
Open this publication in new window or tab >>Multichannel Audio Signal Processing: Room Correction and Sound Perception
2014 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

This thesis concerns and combines multichannel sound reproduction, digital room correction, audio signal processing, and human sound perception. It investigates perceived sound quality and new methods to improve timbral and spatial fidelity of loudspeaker-based multichannel sound reproduction in reverberant environments.

In the first part of the thesis, the perceived sound quality of regular optimized stereo sound systems is investigated by means of a listening experiment based on subjective comparison judgments. It is shown that average listeners' preferences are in favor of the optimized version of the systems.

The second part of the thesis takes on with three novel equalization schemes, which are based on insights from human perception. First, a general filter design framework based on multiple-input multiple-output (MIMO) feedforward control is introduced. The main objective is to provide means to jointly equalize a single loudspeaker by utilizing all available loudspeakers in a multichannel sound system.

Well-known drawbacks of standard multichannel sound reproduction are (a) that symmetrical system setups are generally assumed, and (b) that high fidelity sound reproduction is limited to a tight region in space, the so-called sweet spot. In order to ease drawback (a), the MIMO similarity framework incorporating a pairwise channel similarity requirement is introduced, which is based on a mathematical description of the perception of virtual sound sources created in multichannel sound reproduction. The aim is to obtain similar (symmetrical) room transfer functions in the listening area of a given listening environment. In order to ease drawbacks (a) and (b), the personal audio framework is introduced. It aims at producing filters which improve spatial and timbral sound reproduction in multiple listening positions simultaneously.

Evaluations based on simulations and measurements acquired in representative listening environments strongly indicate that the proposed methods successfully treat several causes which are known to impair sound quality and thus yield improved sound reproduction.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 204 p.
Series
Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-2516 ; 107
Keyword
Audio signal processing, multichannel sound reproduction, equalizers, human sound perception, room correction
National Category
Signal Processing Media Engineering
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-229480 (URN)978-91-554-9010-2 (ISBN)
Public defence
2014-10-03, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2014-09-12 Created: 2014-08-08 Last updated: 2015-01-22Bibliographically approved
Brännmark, L.-J., Bahne, A. & Ahlén, A. (2013). Compensation of Loudspeaker-Room Responses in a Robust MIMO Control Framework. IEEE Transactions on Audio, Speech, and Language Processing, 21(6), 1201-1216.
Open this publication in new window or tab >>Compensation of Loudspeaker-Room Responses in a Robust MIMO Control Framework
2013 (English)In: IEEE Transactions on Audio, Speech, and Language Processing, ISSN 1558-7916, E-ISSN 1558-7924, Vol. 21, no 6, 1201-1216 p.Article in journal (Refereed) Published
Abstract [en]

A new multichannel approach to robust broadband loudspeaker-room equalization is presented. Traditionally, the equalization (or room correction) problem has been treated primarily by single-channel methods, where loudspeaker input signals are prefiltered individually by separate scalar filters. Single-channel methods are generally able to improve the average spectral flatness of the acoustic transfer functions in a listening region, but they cannot reduce the variability of the transfer functions within the region. Most modern audio reproduction systems, however, contain two or more loudspeakers, and in this paper we aim at improving the equalization performance by using all available loudspeakers jointly. To this end we propose a polynomial based MIMO formulation of the equalization problem. The new approach, which is a generalization of an earlier single-channel approach by the authors, is found to reduce the average reproduction error and the transfer function variability over a region in space. Moreover, pre-ringing artifacts are avoided, and the reproduction error below 1000 Hz is significantly reduced with an amount that scales with the number of loudspeakers used.

Keyword
Acoustic signal processing, acoustic modeling, loudspeakers, MIMO, equalizers, sound fields, multichannel audio
National Category
Natural Sciences Engineering and Technology
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-198367 (URN)10.1109/TASL.2013.2245650 (DOI)000316198800008 ()
Available from: 2013-04-15 Created: 2013-04-15 Last updated: 2017-12-06Bibliographically approved
Bahne, A., Brännmark, L.-J. & Ahlén, A. (2013). Symmetric loudspeaker-room equalization utilizing a pairwise channel similarity criterion. IEEE Transactions on Signal Processing, 61(24), 6276-6290.
Open this publication in new window or tab >>Symmetric loudspeaker-room equalization utilizing a pairwise channel similarity criterion
2013 (English)In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 61, no 24, 6276-6290 p.Article in journal (Refereed) Published
Abstract [en]

Similarity of the room transfer functions (RTFs) of symmetric channel pairs is crucial for correct sound reproduction of, for example, stereophonic or 5.1 surround multichannel recordings. This physical and psychoacoustical insight yielded the filter design framework presented in this paper. The filter design framework introduced is based on MIMO feedforward control. It has the aim of pairwise equalization of two audio channels and incorporates two features. In the first place, each channel is individually equalized by minimizing the difference between a desired target response and the original RTF by means of support loudspeakers. The second and novel feature represents the similarity requirement and aims at minimizing the difference between the compensated RTFs of the two channels. In order to asses the proposed method a measure of RTF similarity is proposed. Tests with measurements of two different multichannel audio systems proved the method to be able to significantly improve the similarity of two RTFs.

National Category
Engineering and Technology
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-211854 (URN)10.1109/TSP.2013.2281787 (DOI)000327259500012 ()
Available from: 2013-12-02 Created: 2013-12-02 Last updated: 2017-12-06Bibliographically approved
Bahne, A., Brännmark, L.-J. & Ahlén, A. (2012). Improved loudspeaker-room equalization for stereo systems regarding channel similarity. In: Proceedings - International Conference on Audio, Language and Image Processing. Paper presented at 3rd IEEE/IET International Conference on Audio, Language and Image Processing, ICALIP, Shanghai, CHINA (pp. 254-259). .
Open this publication in new window or tab >>Improved loudspeaker-room equalization for stereo systems regarding channel similarity
2012 (English)In: Proceedings - International Conference on Audio, Language and Image Processing, 2012, 254-259 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, a new approach to robust singlechannel loudspeaker-room equalization for stereo systems based on psychoacoustic insights is presented. Traditionally, in single-channel equalization each channel is equalized individually according to a desired target. In case the target cannot be reached for at least one of the two channels, this approach results in different loudspeaker-room transfer functions of the two channels at the listening position. However, reproducing the intended sound image of stereo recordings requires equal acoustic transfer functions from the input to the two loudspeakers to the listening region. In this paper we aim not only at equalizing the individual channels according to a desired target, but also at explicitly requiring symmetry between the two channels of a stereo system. To this end we propose a two-channel similarity SIMO controller structure, which is an extension to an earlier approach by the authors. The new approach is evaluated based on measurements in a room and is found to reduce differences between the room transfer functions of the two channels in both frequency and time domain.

National Category
Signal Processing
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-181052 (URN)10.1109/ICALIP.2012.6376621 (DOI)978-146730171-8 (ISBN)
Conference
3rd IEEE/IET International Conference on Audio, Language and Image Processing, ICALIP, Shanghai, CHINA
Available from: 2012-09-17 Created: 2012-09-17 Last updated: 2013-02-26Bibliographically approved
Brännmark, L.-J., Bahne, A. & Ahlén, A. (2012). Improved loudspeaker-room equalization using multiple loudspeakers and MIMO feedforward control. In: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference. Paper presented at IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP, 25-30 March, 2012, Kyoto, Japan (pp. 237-240). .
Open this publication in new window or tab >>Improved loudspeaker-room equalization using multiple loudspeakers and MIMO feedforward control
2012 (English)In: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference, 2012, 237-240 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, a new multichannel approach to robust loudspeaker-room equalization is presented. Traditionally, the equalization (or room correction) problem has been treated mostly by single-channel methods, with loudspeaker signals being prefiltered individually by separate scalar filters. Single-channel methods can generally improve the average spectral flatness of the acoustic transfer functions in a listening region, but the variability of the transfer functions within the region cannot be affected. Most modern audio reproduction systems, however, contain two or more loudspeakers, and in this paper we aim at improving the equalization performance by using all available loudspeakers jointly. To this end we propose a general MIMO formulation of the problem, which is a multichannel generalization of an earlier single-channel approach by the authors. The new approach is found to reduce the average reproduction error and the spatial variability of the acoustic transfer functions. Moreover, pre-ringing artifacts are avoided, and the reproduction error below 1000 Hz is significantly reduced with an amount that scales with the number of loudspeakers used.

National Category
Signal Processing
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-181012 (URN)10.1109/ICASSP.2012.6287861 (DOI)000312381400059 ()978-1-4673-0044-5 (ISBN)
Conference
IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP, 25-30 March, 2012, Kyoto, Japan
Available from: 2012-09-14 Created: 2012-09-14 Last updated: 2013-02-18Bibliographically approved
Bahne, A. (2012). Perceived Sound Quality of Small Original and Optimized Loudspeaker Systems. Journal of The Audio Engineering Society, 60(1-2), 29-37.
Open this publication in new window or tab >>Perceived Sound Quality of Small Original and Optimized Loudspeaker Systems
2012 (English)In: Journal of The Audio Engineering Society, ISSN 0004-7554, Vol. 60, no 1-2, 29-37 p.Article in journal (Refereed) Published
Abstract [en]

The perceived sound quality of small loudspeaker systems with and without digital optimization was empirically evaluated in a listening experiment. Further, it was investigated how the presentation order in the performed paired comparisons influenced the results, as well as whether a self-evaluation was of potential use for variance reduction. The systems were optimized by means of FIR filters. The two versions of each loudspeaker system were rated in a paired comparison test for music stimuli. For the purpose of analysis a linear Gaussian model was applied, resulting in an interval scale revealing interesting information about certainty and discrimination ability of the listeners. The test investigated whether linear pre-compensation of small and inexpensive loudspeaker systems results in a significant improvement of the perceived audio quality in a typical listening situation. The results indicated a significant preference for the optimized version and a significant dependency on the presentation order was detected. The self-evaluation was found to be uncorrelated to the test results.

National Category
Signal Processing
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-173831 (URN)000302050900005 ()
Available from: 2012-05-09 Created: 2012-05-07 Last updated: 2017-12-07Bibliographically approved
Bahne, A. (2010). Perceived sound quality of small original and optimized loudspeaker systems. In: 3rd International Workshop on Perceptual Quality of Systems (PQS), Dresden, Tyskland: . Paper presented at 3rd International Workshop on Perceptual Quality of Systems (PQS), Dresden, Tyskland. .
Open this publication in new window or tab >>Perceived sound quality of small original and optimized loudspeaker systems
2010 (English)In: 3rd International Workshop on Perceptual Quality of Systems (PQS), Dresden, Tyskland, 2010Conference paper, Published paper (Refereed)
National Category
Signal Processing
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-133008 (URN)
Conference
3rd International Workshop on Perceptual Quality of Systems (PQS), Dresden, Tyskland
Available from: 2010-11-01 Created: 2010-11-01 Last updated: 2016-04-18Bibliographically approved
Johansson, M., Brännmark, L.-J., Bahne, A. & Sternad, M. (2009). Sound field control using a limited number of loudspeakers. In: 36th Audio Engineering Society International Conference 2009: Automotive Audio - Sound in Motion, Dearborn, Michigan: . Paper presented at 36th Audio Engineering Society International Conference 2009: Automotive Audio - Sound in Motion, Dearborn, Michigan. Red Hook, NY: Audio-Engineering Society.
Open this publication in new window or tab >>Sound field control using a limited number of loudspeakers
2009 (English)In: 36th Audio Engineering Society International Conference 2009: Automotive Audio - Sound in Motion, Dearborn, Michigan, Red Hook, NY: Audio-Engineering Society , 2009Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Red Hook, NY: Audio-Engineering Society, 2009
National Category
Signal Processing
Research subject
Electrical Engineering with specialization in Signal Processing
Identifiers
urn:nbn:se:uu:diva-111481 (URN)9781615673377 (ISBN)
Conference
36th Audio Engineering Society International Conference 2009: Automotive Audio - Sound in Motion, Dearborn, Michigan
Available from: 2009-12-15 Created: 2009-12-15 Last updated: 2016-04-14Bibliographically approved
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