2007 July/August, Volume 55 Number 7/8

CONTENTS

PAPERS

Modeling of Loudspeaker Systems Using High-Resolution Data
Stefan Feistel and Wolfgang Ahnert   571
High-resolution data is needed to model the behavior of configurable loudspeaker systems or combinations of such systems. This is especially true when digital signal processing is used to compensate for physical deficiencies. It is essential that complex data of high spatial and spectral resolutions be utilized. To describe the mechanical, electronic, and acoustic characteristics of complex loudspeaker systems adequately, a new data format is proposed. In order to validate the proposed methodology, comparisons between measured and calculated performance are made with loudspeakers of different types, including multiway loudspeakers, clusters, and line-array systems. Good agreement is found between balloon data and simulated directivity patterns. An introduction into the mathematical framework is given.

Robust Two-Dimensional Surround Sound Reproduction for Nonuniform Loudspeaker Layouts
Mark Poletti   598
A panning function for positioning a sound source in surround sound configurations with a nonuniform layout presents special problems. Although theoretical solutions exist, they produce large interference effects for positions at a distance from the array center. In contrast, a least-square method produces a robust panning function with a more consistent directionality. A penalty function for those loudspeakers that are far from the intended virtual source angle improves performance. In general, robustness trades against accuracy.

Thresholds of Detection for Changes to the Q Factor of Low-Frequency Modes in Listening Environments
M. R. Avis, B. M. Fazenda, and W. J. Davies   611
Because relatively high-Q resonance modes are one of the main problems in sound reproduction in rooms, it is useful to know the threshold for detecting changes in the Q of such modes. Empirical tests show that below a Q of 16 a further reduction is not perceptible. Low-Q modes correspond to a dead room. This conclusion results from tests that use music rather than pure tones or noise. Also the evaluation uses multiple modes rather than a single mode in isolation, which is a more realistic approximation in a real room configuration.

Multiple Exponential Sweep Method for Fast Measurement of Head-Related Transfer Functions
Piotr Majdak, Peter Balazs, and Bernhard Laback   623
Head-related transfer functions (HRTF) are essential for simulating virtual environments from free-field audio, but they take a large amount of time to achieve. A new method significantly reduces the acquisition time. The method optimizes multiple overlapping exponential sweeps to acquire the collection of impulse responses without degrading the signal-to-noise ratio. A demonstration example of an HRTF set with 1550 positions is measured four times faster than the conventional approach. The method can also be used for extracting the spatial characteristics of microphones and other devices with spatially dependent responses.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   638
Coarse-groove calibration disc; surface scattering uniformity; digital audio measurements; digital input/output interfacing; audio file exchange and transfer; audio connectors

FEATURES

122nd Convention Report, Vienna   642
     Exhibitors   659
123rd Convention Preview, New York   662
     Exhibit Previews   664
Analysis, Synthesis, Voice   695
Education News   702

DEPARTMENTS

AES Awards   665
News of the Sections   704
Upcoming Meetings   706
Sound Track   707
Membership Information   708
Advertiser Internet Directory   709
In Memoriam   711
Sections Contacts Directory   712
AES Conventions and Conferences   720

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2007 July/August, Volume 55 Number 7/8

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