1996 APRIL, VOLUME 44 NUMBER 4

CONTENT

PAPERS

A Comparison of Dithered and Chaotic Sigma-Delta Modulators
Chris Dunn and Mark Sandler p. 227
High-order single-bit sigma-delta modulators exhibit low-level artifacts, such as idle tones and noise modulation. This study of high-order sigma-delta modulators compares the trade offs between various dither and chaotic modulator configurations. This is part of an ongoing study to reduce unwanted artifacts in high-order sigma-delta modulators.

Harmonic Balance Method for Estimating the Nonlinear Parameters of Electrodynamic Direct-Radiator Loudspeakers
Hyuk Jeong and Jeong-Guon Ih p.245
Harmonic component loudspeaker outputs can be accurately estimated by this unique harmonic balance method. The results of these computations can be used subsequently to develop active compensation circuits to reduce harmonic distortion products from a defined direct-radiator loudspeaker.

New Method of Characterizing Driver Linearity
Jonathan Scott, Jonathan Kelly, and Glenn Leembruggen p. 258
A new, simple method for determining nonlinear loudspeaker parameters and correlating the measured findings to loudspeaker harmonic distortion output products is demonstrated. Comparisons of the predicted and measured nonlinear results are very close, and thus present a definitive analytical tool to aid loudspeaker designers in improving loudspeaker linearity.

Optimizing the Decay Range in Room Acoustics Measurements using Maximum-Length-Sequence Techniques
John S. Bradley p. 266
Improved room acoustic measurements are made possible by considering some of the influencing parameters while using new computer-based correlation software techniques. Signal correlation can improve the ability of the system to extract low-level reverberant signals from the noise floor, thus enhancing the signal's reverberation time measurement reliability.

STANDARDS AND INFORMATION DOCUMENTS

AES27-1996 AES recommended practice for forensic purposes Managing recorded audio materials intended for examination p. 274

DRAFT AES22-xxxx, DRAFT Recommended practice for audio preservation and restoration - Storage of polyester-base magnetic tape (insert)

AES Standards Committee News p. 284 AES27-1996 review; status of projects

FEATURES

Audio Compression for Network Transmission
Martin Dietz, Harald Popp, Karlheinz Brandenburg, and Robert Friedrich p. 58

AES News p. 82 Audio and MIDI Markup Tools for the World Wide Web
Bruce Pennycook p. 290

Updates and Corrections to the 1995/1996 AES International Sections Directory p. 303

DEPARTMENTS

Review of Acoustical Patents p. 287
News of the Sections p. 298
Sound Track p. 305
Upcoming Meetings p. 308
New Products and Developments p. 310
Available Literature p. 312
Membership Information p. 314
Audio Engineering Society Application Instructions p. 317
AES Special Publications p. 320
Sections Contacts Directory p. 324
AES Conventions and Conferences p. 328