2008 January/February, Volume 56 Number 1/2

CONTENTS

PAPERS

Objective Measurement of Perceived Auditory Quality in Multichannel Audio Compression Coding Systems
Inyong Choi, Barbara G. Shinn-Cunningham, Sang Bae Chon, and Koeng-Mo Sung   3
An objective method that predicts perceived audio quality in multichannel compression coding systems is described. This method, which takes into account degradation in both spatial and timbral quality, extends previous approaches by incorporating a binaural hearing model. Spatial quality uses three interaural distortions metrics: time difference, level difference, and cross-correlation coefficient. Timbral quality uses 10 nonspatial statistics. Predictions of perceived quality are comparable or better than other models.

Control of Synthesized Vibrato during Portamento Musical Pitch Transitions
Robert C. Maher   18
Vocal vibrato, a naturally occurring pitch oscillation in singing, requires careful analysis in the vicinity of portamento transitions from one pitch to another. Measurements show that singers manage to align pitch transitions to the natural shape of the vibrato cycle. Vibrato continuity is preferred to timing accuracy. Although singers do not report being conscious of this subtlety, the characteristic is quite consistent. These results show that in order to mimic natural vocal vibrato, a vocal synthesizer must synchronize the main pitch transition and the phase of the vibrato oscillator.

A New HRTF Interpolation Approach for Fast Synthesis of Dynamic Environmental Interaction
Fakheredine Keyrouz and Klaus Diepold   28
In order to achieve a realistic rendering of moving sound sources and changes in listener position with real-time virtual auditory spaces, a very dense grid of head-related transfer functions (HRTFs) is required for interpolation. A new binaural interpolation algorithm based on a block Loewner matrix is proposed to avoid artifacts with dynamic changes in the HRTF. Compared to existing algorithms, the new method is both accurate and efficient. Subjective tests were used to verify the technique.

ENGINEERING REPORTS

Nonlinear Intermodulation of Two Coherent Acoustic Progressive Waves Emitted by a Wide-Bandwidth Loudspeaker
Guy Lemarquand and Michel Bruneau   36
The usual assumption that air provides a linear medium for sound propagation is not valid at high intensities. An analytic procedure and experimental measurements show that when two harmonic waves propagate, an intermodulation phenomenon appears because nonlinear acoustic phenomena occur in fluid media. Regardless of the quality of the loudspeaker, high-fidelity sound reproduction is theoretically impossible with high particle velocity.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   45
Special report on wide-area synchronization; carriage of MPEG Surround in AES3; Amendment 5 to AES3; forensic use of electric-network frequency analysis; file-size extension for Broadcast Wave (BWF) files; loudspeaker modeling and measurement

FEATURES

Understanding Sigma–Delta Modulation: The Solved and Unsolved Issues   Joshua D. Reiss   49
DSP in Loudspeakers   Francis Rumsey   65
Anatomy of the Soundscape: Evolving Perspectives   Bernie Krause   73
34th Conference, Seoul, Call for Papers   102
125th Convention, San Francisco, Call for Papers   103

DEPARTMENTS

News of the Sections   81
Upcoming Meetings   85
Sound Track   87
New Products and Developments   88
Membership Information   89
Advertiser Internet Directory   94
In Memoriam   100
Sections Contacts Directory   104
AES Conventions and Conferences   112

FPO For the cover:

2008 January/February, Volume 56 Number 1/2

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