1999 October, VOLUME 47 NUMBER 10

CONTENT

President's Message David P. Robinson 785

PAPERS

Attack and Release Time Constants in RMS-Based Feedback Compressors Fred Floru 786

Mathematical models for feedback and feedforward compressors are developed in this paper. The
author analyzes the transfer functions for a linear-output rms detector in conjunction with a linearly
controlled VCA (linear-domain compressor) and a logarithmic-output rms detector in conjunction
with an exponentially controlled VCA (log-domain compressor). It is shown that both transfer
functions are equivalent. Comparisons between feedback and feedforward configurations are
discussed to optimize their attributes for specific applications.

ENGINEERING REPORTS

Applications of Digital Watermarking Technology in Audio Signals
Changsheng Xu, Jiankang Wu, Qibin Sun, and Kai Xin 803

Protection of audio intellectual properties has become a subject of great concern in the digital age of
audio. Audio watermarking techniques are compared and discussed relative to the need for
robustness and adaptability to the program material in which the watermark is embedded, and its
transparency within the program content. The authors propose a content-adaptive multiple-echo
hopping technique to embed the watermark into audio signals, which is claimed to be superior to
many of the current systems. It is anticipated that reliable watermarking will become even more
important as digital techniques expand.

Modeling the Woodstock Gamelan for Synthesis Lydia Ayers and Andrew Horner 811

A Csound implementation for synthesizing Woodstock gamelan tones has been developed. This
synthesized model produces tones that are very close to the original instrument's tones, according to
listening tests. It can also produce attractive related timbres with simple changes to the model
parameters.

Virtual Acoustic Displays for Teleconferencing: Intelligibility Advantage for "Telephone Grade"
Audio Durand R. Begault 822

The advantages of virtual acoustic (3-D audio) displays to achieve spatial separation for stereo
headphone users have been investigated by the author. The technique separates multiple
communication channels by placing each sound source at a unique virtual audio position, thereby
simulating and exploiting the "cocktail party" effect. This approach increases the intelligibility of
audio signals against noise in an "unmasking" process.

STANDARDS AND INFORMATION DOCUMENTS

AES33-1999 AES standard -- For audio internconnections -- Database of multiple-program
connection configurations 827

DRAFT AES43-xxxx AES standard for forensic audio -- Criteria for the authentication of
analog audio tape recordings (insert)

AES Standards Committee News 833

Loudspeaker modeling and measurement

FEATURES

9th Tokyo Regional Convention Report 836

Exhibitors 846

Program 847

AES Officers 1999/2000 854

Review of Society's Sustaining Members 859

Call for Nominations for Awards 886

DEPARTMENTS

News of the Sections 876

Sound Track 880

Upcoming Meetings 881

New Products and Developments 882

Available Literature 883

Membership Information 887

In Memoriam 891

AES Annual Report 892

Audio Engineering Society Membership
Application Instructions 893

Sections Contacts Directory 896

AES Conventions and Conferences 902

In this issue...

Compressor Transfer Functions

Transparent Audio Watermarking

Woodstock Gamelan Synthesis

Enhancing Perceived Intelligibility

Standards: Multiple-contact
connector database

Features...

9th Tokyo Regional
Convention Report

New AES Officers

Review of Society's
Sustaining Members

Call for Nominations
for Awards

FPOFor the cover:

Volume 47 Number 10 1999 October

spine:VOLUME 47, NO. 10 1999 OCTOBER