1999 March, VOLUME 47 NUMBER 3

CONTENT

PAPERS

Evaluation of Artificial Heads in Listening Tests
Henrik Møller, Dorte Hammershøi, Clemen Boje Jensen, and Michael Friis Sørensen 83

The subjects in this presentation listened to and compared real sound fields to artificial-head
recordings of the same sound field. This study was designed to evaluate comparative localization
performances of artificial heads. The results of listeners' localization performance tests, when
comparing artificial-head recordings to those of the real sound fields, resulted in an increased
number of errors. The results obtained when using some of the artificial heads in this study also
showed an increase in confusion of directionality perception outside the median plane. The overall
conclusion indicated the need for an improved artificial-head design.

Modeling Piano Tones with Group Synthesis Kathy Lee and Andrew Horner 101

Synthesizing piano sound is a difficult task because it is subject to spectral changes during its long
decay. Group synthesis, a special case of wavetable synthesis, has been adapted by the authors to
efficiently model piano sounds. It requires about one half the data allocation required by additive
synthesis. This solution is computationally about twice as fast as additive synthesis. Plucked strings,
percussive mallet sounds, and bell tones are good future test cases for this synthesis model.

ENGINEERING REPORTS

Noise Relations for Parallel Connected Transistors W. Marshall Leach, Jr. 112

The noise performance of an amplifier's input stage consisting of a number of parallel connected
semiconductor devices is examined. The resultant equivalent input voltage noise is measured while
keeping the bias current constant and varying the number of input devices. The result is then
compared to the noise while holding the bias current per device constant. The findings of this study
contribute significantly to the understanding of low-noise amplifier input system designs.

Acoustics of Russian Classical Opera Houses Michael Lannie and Leonid Makrinenko 119

Acoustic problems attendant to Russian theaters, which were built in classical style, having
horseshoe-shaped floor plans with several rows of balconies, were investigated. Reverberation times
of these old halls were measured under varying conditions and the results analyzed. The goal of this
investigation was to make suggestions for renovating the old halls to improve their acoustical
performance. This study also provides acoustic guidelines for the design of future performance halls.

STANDARDS AND INFORMATION DOCUMENTS

AES3-1992 Amendments to AES Recommended practice for digital audio engineering -- Serial
transmission format for two-channel linearly represented digital audio data 130

Amendment 1 131 Amendment 2 135

Amendment 3 137

AES Standards Committee News 143

AES24; connector database; loudspeaker measurement; room acoustics; 1394 synchronization;
AES3 in MPEG; phonograph record restoration; AES3 synchronization; digital interfaced
microphones; grounding and EMC

FEATURES

106th Convention Preview, Munich, Germany 150

Calendar 152

Exhibitors 154

Exhibit Previews 159

The Future of Audio Recording Kees A. Schouhamer Immink 171

AES News: AES Presents White Paper on Audio Quality for Internet 179

Education News 180

DEPARTMENTS

Upcoming Meetings 172

News of the Sections 173

Sound Track 181

Available Literature 182

Membership Information 185

In Memoriam 189

Audio Engineering Society Membership

Application Instructions 191

Sections Contacts Directory 194

AES Conventions and Conferences 200

In this issue...

Artificial-Head Evaluation

Wavetable Group
Synthesis

Parallel Connected
Transistor Noise

Modernizing Classical
Hall Designs

Standards:
AES3 Amendments

Features...

106th Convention, Munich--Preview

Future of Audio Recording

AES Internet Audio
White Paper

Education News

FPOFor the cover:

Volume 47 Number 3 1999 March

spine:VOLUME 47, NO. 3 1999 MARCHBoiler, p. 2(ISSN 0004-7554), Volume 47, Number 3, 1999 March