1999 July/August, VOLUME 47 NUMBER 7/8

CONTENT

PAPERS

Controlled Subjective Assessments of Two-to-Five-Channel Surround Sound Processing
Algorithms Francis Rumsey 563

Several algorithms for expanding several types of two-channel stereo programs to five-channel
surround sound were evaluated by listening panels at the Research and Development Department
of the British Broadcasting Corporation. It was considered important to know what effect these
processes might have on the quality of sound reproduction and if listeners judged the processed
versions superior to the original two-channel program material. Although there were no definitive,
single-answer conclusions to these tests, there were some additional unanswered questions raised
concerning the use of dipole loudspeakers and comparison listening tests between discrete five-
channel programs and two-to-five expanded program materials.

Digital Filter Design for Inversion Problems in Sound Reproduction
Ole Kirkeby and Philip A. Nelson 583

The authors studied digital filters that were designed to eliminate the influence of a loudspeaker's
room response, and the subsequent excessive boost of frequencies that occurred just below the
Nyquist frequency. Designing digital filters for a multichannel virtual source imaging system
presents a similar problem. A time-domain filter design method can be used for efficient
deconvolution of single and mutlichannel systems.

ENGINEERING REPORTS

Building a Plane-Wave Tube: Experimental and Theoretical Aspects
Roberto Magalotti, Carlo Zuccatti, and Paolo Pasini 596

The primary purpose of this report is to describe the building and testing of a plane-wave tube for
measuring compression drivers in an audio laboratory. A new method for testing the tube for
undesired reflections was devised, with and without sound absorbing materials. The experimental
results show good agreement with the predicted behavior outlined in the AES document on
plane-wave tubes, and confirm the predictions on usable bandwidth limits.

Audio Sound Reproduction Based on Nonlinear Interaction of Acoustic Waves
Dong Weiguo and Wu Qunli 602

The authors investigated audio sound reproduction based on nonlinear interaction of acoustic waves
in a duct. Special emphasis was given to the sum and difference frequencies generated by the
nonlinear behavior of the acoustic waves. When the frequencies of the two primary waves were
increased to the ultrasonic spectrum, the audible resultant sound was attributable to the difference
wave. This finding suggested the possibility of audio sound reproduction which uses the nonlinear
interaction attributes of two ultrasonic waves.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News 607

Standards groups meeting at the 107th convention; listening tests; preservation of recorded tapes; digital measurements; mechanical disc reproduction; digital synchronization

FEATURES

107th Convention Preview, New York 612

Calendar 614

Exhibitors 616

Exhibit Previews 624

DEPARTMENTS

News of the Sections 654

Upcoming Meetings 658

Sound Track 659

Available Literature 660

Membership Information 663

Sections Contacts Directory 666

AES Conventions and Conferences 672

In this issue...

Surround Sound
Synthesis Study

Digital Filter Design

Plane Wave Tube Studies

Nonlinear Interaction of
Acoustic Waves

Features...

107th Convention,
New York--Preview

FPOFor the cover:

Volume 47 Number 7/8 1999 July/August

spine:VOLUME 47, NO. 7/8 1999 JULY/AUGUST