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Paper #558, Session SS28D. STEREOPHONIC PERSONAL AUDIO REPRODUCTION USING PLANARITY CONTROL OPTIMIZATION. 15 th July 2014. Philip Coleman, Philip J. B. Jackson, Marek Olik [email protected] Centre for Vision, Speech and Signal Processing, - PowerPoint PPT Presentation
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STEREOPHONIC PERSONAL AUDIO REPRODUCTION USING PLANARITY CONTROL OPTIMIZATION
Philip Coleman, Philip J. B. Jackson, Marek [email protected]
Centre for Vision, Speech and Signal Processing,
University of Surrey, Guildford, Surrey, GU2 7XH, UK
Jan Abildgaard PedersenBang & Olufsen A/S
(now with Dynaudio A/S, Sverigesvej 15, 8660 Skanderborg, DK)
15th July 2014
Paper #558, Session SS28D
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planarity control optimization
Introduction
• Personal sound is an active research topic
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planarity control optimization
Introduction
• Two main approaches to sound zones [1]
- Energy cancellation- Least-squares error minimization
• Previous reported results limited to mono• Likely requirement for stereo from consumers• We investigate stereophonic personal audio
[1] P. Coleman, P. J. B. Jackson, M. Olik, M. Møller, M. Olsen, and J. Pedersen, “Acoustic contrast, planarity and robustness of sound zone methods using a circular loudspeaker array,” J. Acoust. Soc. Am. 135(4), p.1929-1940, 2014.
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planarity control optimization
Background
• Create two virtual loudspeakers and quiet zone
• Require control of energy directionTarget listener gets stereo image
Listener in quiet zone undisturbed
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planarity control optimization
Background
Zone AZone B
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planarity control optimization
Cost functions
• Planarity control (PC) [2]
constraint on source weights
dark zone energy
bright zone energy projected in to angular domain [3]
[2] P. Coleman, P. J. B. Jackson, M. Olik, and J. Pedersen, “Optimizing the planarity of sound zones,” in Proc. 52nd AES Int. Conf., Guildford, UK, 2-4 Sept. 2013.[3] Chang, J. H., Choi, J. W., & Kim, Y. H. (2010). A plane wave generation method by wave number domain point focusing. J. Acoust. Soc. Am., 128, 2758.
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planarity control optimization
Cost functions
• Planarity control (PC)
- Steering matrix [4]
- Pass-rangemicrophones
angles
[4] P. J. B. Jackson, F. Jacobsen, P. Coleman and J. Pedersen, “Sound field planarity characterized by superdirective beamforming”, in Proc. 21st ICA, Montreal, 2-7 June 2013.
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planarity control optimization
Cost functions
• Pressure matching (PM; plane-wave target) [5]
pressure in the dark zone + bright zone reproduction error
[5] M. Poletti, “An investigation of 2-d multizone surround sound systems”, in Proc.125th AES Conv., San Francisco, CA, 2-5 October 2008.
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planarity control optimization
Reproduction setup
• 60 channel circular circular array
• Two 25 × 35 cm zones• Calculate weights for each frequency (A/B;L/R)• Independent performance measurement set
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Evaluation
• Acoustic contrast
• RMSE of energy direction
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planarity control optimization
Results
• Measured acoustic contrast (both channels)
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Results
• Accuracy of energy placement
Left channel Right channel
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planarity control optimization
Results
• Some higher frequencies have higher RMSE- Some energy at target location
Measured
PC left channel 2350 Hz
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planarity control optimization
Results
• Some higher frequencies have higher RMSE- Some energy at target location- Failure for some grating patterns
PC RightPM LeftPC Left
120
SP
L (d
B)
0
Free-field simulations, 2350 Hz
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How does it sound?
• Hear for yourself!
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Results
• Results summary
- PC gives best contrast- PM gives best accuracy of energy direction- Differing behavior above array aliasing limit
250-2000 Hz 100-7000 Hz
PC PM PC PM
RMSE left (deg) 4.2 2.8 40 4.1
RMSE right (deg) 4.5 3.6 6.3 5.2
Combined contrast (dB) 26 20 15.7 12.1
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Summary
• Previous personal audio work in mono• Extension to stereo investigated• Implemented PC and PM on 60 channel circle• PC gave up to 30dB contrast • PC 6 dB greater contrast than PM
(freq. ave., 250-2000 Hz)• PM placement 1.2 degrees more accurate
(channel & freq. ave., 250-2000 Hz)• Further work should investigate perception
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Numerical optimization of loudspeaker configuration for sound zone reproduction
Paper #219, Session SS06A
Interested in personal audio?
Stereophonic personal audio reproduction using planarity control optimization
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planarity control optimization
Acknowledgements
www.linkedin.com/in/philipcolemanaudio
Thanks to Alice Duque who made RIR measurements
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