2003 July/August, Vol 51 Number 7/8

CONTENT

PAPERS

Full-Sphere Sound Field of Constant-Beamwidth Transducer (CBT) Loudspeaker Line Arrays
D. B. (Don) Keele, Jr.   611
Unlike a linear-line array of loudspeakers, which has no means of controlling the horizontal beamwidth, a curved-line circular-arc array exhibits useful properties in three dimensions. Based on a computer simulation, the author shows that the configuration provides horizontal directivity in addition to the expected vertical control. Such arrays have a pear-shaped pattern that is surprisingly uniform over the frequency range. The bending is an extra degree of freedom that allows more control over the radiation pattern.

Direct-Radiator Loudspeaker Systems with High Bl
John Vanderkooy, Paul M. Boers, and Ronald M. Aarts   625
Increasing the magnetic motor strength of a driver not only improves the efficiency of the loudspeaker and amplifier, but also improves other tradeoffs in the design process. Box volume can be decreased. A study demonstrated the advantages for a small sealed-box configuration, although equalization is required to restore a flat response. Vented systems do not benefit as much from this approach.

Psychoacoustic Investigations On Sound-Source Occlusion
Hania Farag, Jens Blauert, and Onsy Abdel Alim   635
Virtual space simulation is actually a collection of acoustic attributes, which include objects that cast auditory shadows, an effect known as occlusion. Objects block and change the perception of sound when they are located between the source and the listener. Experiments show that the perceived location of an occluded source is shifted to the edge closest to the listener, which simplifies the computational burden of modeling occluding objects. This result is consistent with the precedence effect.

ENGINEERING REPORTS

The Differential Pressure Synthesis Method for Efficient Acoustic Pressure Estimation
Yufei Tao, Anthony I. Tew, and Stuart J. Porter   647
Calculating the sound field around a complex object, such as the pressure at the two ears of a head, is computationally intensive. Rather than a direct computation, the authors demonstrate an incremental approach to a reference template. The pressure changes produced by each spherical harmonic are precomputed and stored in a database. The target shape is then decomposed into the template references and the sum of spherical harmonics, each of which contributes an incremental change to the pressure. In the case of a dummy head, the results were accurate for wavelengths that were large compared to the spatial perturbations.

LETTERS TO THE EDITOR

Comments on "Deciphering an Enigma"
Marianna Sankiewicz and Gustaw Budzynski   657

Author's Reply to "Comments on 'Deciphering an Enigma'"
Steven Harris   657

STANDARDS AND INFORMATION DOCUMENTS

AES47-2002 AES standard for digital audio-Digital input-output interfacing-Transmission of digital audio over asynchronous transfer mode (ATM) networks   659
AES-R4-2002 AES standards project report-Guidelines for AES standard for digital audio- Digital input-output interfacing-Transmission of digital audio over asynchronous transfer mode (ATM) networks, AES47   684

AES Standards Committee News   704
Mechanical media; audio storage and handling; listening tests; audio connectors; grounding and EMC; audio file transfer and exchange

FEATURES

115th Convention Preview, New York   714
     Calendar   716
     Exhibitors   717
     Exhibit Previews   722
Demystifying Audio Metadata   744
116th Convention, Berlin, Call for Papers   768
25th Conference, London, Call for Papers   769

DEPARTMENTS

Review of Acoustical Patents   710
News of the Sections   752
Sound Track   756
Available Literature   757
Upcoming Meetings   758
Membership Information   759
Advertiser Internet Directory   762
In Memoriam   766
Sections Contacts Directory   770
AES Conventions and Conferences   776

FPO For the cover:

2003 July/August, Vol 51 Number 7/8

spine: 2003 July/August, Vol 51 Number 7/8