Volume 57 Number 1/2 2009 January/February
CONTENTS

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Editor's Note, paper review process (PDF-110KB)         John Vanderkooy    3

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PAPERS
Hierarchical Bandwidth Limitation of Surround Sound—Part II: Optimization of Bandwidth Allocation Strategy (PDF-259KB) (HI-RES PDF-800KB)  
Yu Jiao, Sławomir Zielinski, and Francis Rumsey    5
A technique for band limiting a multichannel surround sound, previously described, requires an optimization strategy based on subjective testing. In this technique, the 5 channels are transformed into a hierarchical domain where each transformed signal is assigned some percentage of the available bandwidth. Two cases with total bandwidth of 40 and 60 kHz were tested using a wide range of audio samples, and the resulting audio quality on a 100-point scale was rated at 87 and 93, respectively. This technique was superior to traditional bandwidth-limiting algorithms.  

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Concept, Design, and Implementation of a General Dynamic Parametric Equalizer (PDF-416KB) (HI-RES PDF-1.4MB)  
Duane K. Wise    16
While parametric equalization and dynamic processing have been around since the early twentieth century, and while they are both a mainstay of audio engineers, they are seldom combined into a single operation. A digital system is described in which dynamic processing is designed to operate with the building blocks of a parametric equalizer. This provides to the user time-varying amplitude control in selected frequency bands. Audio mastering and audio reinforcement would benefit from the integration of equalization and dynamics as a single tool.  

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Sound Texture Synthesis Using an Overlap–Add/Granular Synthesis Approach (PDF-284KB) (HI-RES PDF-938KB)  
Martin Fröjd and Andrew Horner    29
Creating an arbitrary length audio background sound, called sound texture, from a small original source is a form of sound synthesis. For example, in video games it may be desirable to continue the aural impression of blowing wind or background traffic for as long as the player remains in a scene that requires that background. Using a block segmented overlap and add algorithm with crossfades, the resulting sound preserves the subjective characteristics of the original yet without being perceived as repetitive. The original source is partitioned into blocks, which are then randomly sequenced. Block length of 2 seconds is optimum.  

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ENGINEERING REPORTS
Design and Performance of a Sigma–Delta Digital Loudspeaker Array Prototype (PDF-388KB) (HI-RES PDF-2.7MB)  
Nicolas-Alexander Tatlas, Fotios Kontomichos, and John Mourjopoulos    38
While experimental prototypes of digital loudspeaker arrays usually use a PCM format, preliminary results show that sigma–delta technology is also a viable alternative. In the test configuration, an FPGA is connected to 32 autonomous true-digital amplifiers driving a corresponding number of miniature moving-coil loudspeakers organized in an array. The sigma–delta approach produces comparable results but with lower harmonic distortion, especially off axis and at mid-frequencies.  

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STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News (PDF-2.0MB)    46
Shielding of cables; angular measurement of polar radiation; forensic audio; loudspeaker modeling and measurement; audio connectors  
 
FEATURES
Novel Transducers (PDF-2.1MB) (HI-RES PDF-12.8MB)   Francis Rumsey    50

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14th Regional Convention, Tokyo, Call for Papers (PDF-71KB)    78
127th Convention, New York, Call for Papers (PDF-76KB)    79
 
DEPARTMENTS
News of the Sections (PDF-1.9MB)    56
AES Awards (PDF-213KB)    66
Sound Track (PDF-119KB)    68
New Products and Developments (PDF-67KB)    70
Available Literature (PDF-89KB)    71
Upcoming Meetings (PDF-43KB)    72
Membership Information (PDF-361KB)    73
Advertiser Internet Directory (PDF-173KB)    77
Sections Contacts Directory (PDF-161KB)    80
AES Conventions and Conferences (PDF-564KB)    88
 
EXTRAS
Cover & Sustaining Members List (PDF-82KB)    
AES Officers, Committees, Offices & Journal Staff (PDF-102KB)    
Advertisements (PDF-1.0MB)