2008 May, Volume 56 Number 5

CONTENTS

PAPERS

Subjective Intelligibility Evaluation in Multiple-Talker Situation for Virtual Acoustic Opening-Based Audio Environments
J. A. Beracoechea, S. Torres-Guijarro, L. García, F. J. Casajús-Quirós, and L. Ortiz   339
A virtual conferencing system, which couples two separated rooms as if they were a single virtual space connected by an open window, can be implemented in a variety of ways. This study examines the performance of four approaches using the metric of intelligibility with multiple simultaneous talks as the criterion. The problem is constrained by the amount of computation required, limitations on channel capacity, reverberation in the source space, and the difficulty using beamforming to isolate talkers and reduce acoustics contamination. Many improvements were not linear once a threshold level of performance was achieved.

Source Placement for Equalization in Small Enclosures
Nick Stefanakis, John Sarris, and George Cambourakis   357
A theoretical study explores the way in which sound equalization of the magnitude response in enclosed spaces can be achieved by controlling source locations. The optimization aims to create the desired sound pressure corresponding to that of a plane wave. Sources are placed so that they couple to the beneficial room modes while avoiding those modes that would degrade performance. Simulation results for a rectangular room and an automobile cavity show the benefits: reduced error and increased spatial robustness.

Development of a Super-Wide-Range Microphone for Sound Recording
Kazuho Ono, Takehiro Sugimoto, Hayao Tanabe, Masakazu Iwaki, Koichi Kurozumi, Akio Ando, and Keishi Imanaga   372
A new design for a super-wide-range microphone overcomes the conventional tradeoff between noise and bandwidth. Rather than reduce the size of the sensing element to extend the bandwidths to 100 kHz, this design explicitly takes advantage of high-frequency scattering by the microphone body and resonances of the diaphragm. This extends the frequency range, while still preserving the low noise of larger transducers. Laboratory measurements of the resulting omnidirectional electrostatic microphone validate the design approach.

ENGINEERING REPORTS

Application of Wavelets to Onset Transients and Inharmonicity of Piano Tones
Enbo Wang and B. T. G. Tan   381
The wavelet packet transform is particularly useful in analyzing the onset transients of piano tones as a means of capturing the unique attributes of such signals in an efficient way. This approach also allows the inhamonicity coefficients to be determined. By exploiting the fact that energy is concentrated in a few time-frequency blocks, a small number of such blocks, especially in the lower harmonics, are sufficient to accurately reconstruct the original waveform. Piano tones have rapidly rising onset transients resulting from the hammer striking the strings and before the string reaches steady state.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   393
Digital input-output interfacing; audio metadata

FEATURES

Loudspeakers, Reflections, and Rooms   Francis Rumsey   394

DEPARTMENTS

Upcoming Meetings   400
News of the Sections   401
Sound Track   407
New Products and Developments   409
Membership Information   410
Advertiser Internet Directory   411
Sections Contacts Directory   416
AES Conventions and Conferences   424

FPO For the cover:

2008 May, Volume 56 Number 5

spine: 2008 May, Volume 56 Number 5