2006 June, Volume 54 Number 6

CONTENTS

PAPERS

Loudspeakers and Rooms for Sound Reproduction-A Scientific Review
Floyd E. Toole   451
Much of our understanding of how listeners hear spatial acoustics originates from studies with large spaces, notably concert halls. While the resulting insights are frequently extended to small spaces, other phenomena weaken the validity of conclusions. Listeners may be adapting to the complexities of reflections and resonances in small spaces, thereby reducing or eliminating the perception of measured degradation. Informal evidence from the professional recording industry suggests that humans compensate and adapt to the acoustical anarchy of complex sound fields.

A Comparison of the "Pruned Tree" versus "Stack" Algorithms for Look-Ahead Sigma-Delta Modulators
J. A. S. Angus   477
High-order Sigma-Delta modulators, used in high-quality converters, cannot use aggressive noise-shaped filtering because the one sample delay in the feedback produces instability under overload conditions. Various solutions have been proposed, but computational burdens grow exponentially with increases in the look-ahead depth. Pruning the choices reduces the burden but at the risk of discarding the optimum choice. A comparison of the "pruned tree" and the "stack" algorithms shows that the former is most efficient even though the latter has better theoretical performance.

Evaluation of Sound Quality, Boominess, and Boxiness in Small Rooms
Adam Weisser and Jens Holger Rindel   495
Subjective listening tests were conducted in seven small rooms to investigate those physical attributes that correspond to the perception of boominess and boxiness. Three new acoustic metrics-small room bass ratio, small room early decay time ratio, and low-high ratio-proved to be better predictors of sound quality than conventional measures. However, the type of audio, namely music or speech, influenced preference and quality judgments. Speech was best in rooms with weak reverberation, whereas a preferred range of reverberation was found for music.

ENGINEERING REPORTS

Effect of Reflectors on Sound-Source Localization with Two Microphones
Sandeep A. Phatak, Rama Ratnam, Bruce C. Wheeler, William D. O'Brien, Jr., and Albert Feng   512
The performance of algorithms that extract source location using a pair of microphones degrades in either reverberant conditions or the presence of parallel reflectors. Localization of signals such as white noise, which are very broadband, is more robust than with speech, which can be narrow band. Reverberation produces excessive temporal smearing at low frequencies. Finally, the localization-extraction algorithm, which is frequency-based, proved more reliable than the commonly used multiple signal classification algorithm.

FEATURES

29th Conference Preview, Seoul   526
   Calendar   528
   Program   530
   Registration Form   535
Enhanced Multichannel Audio   536
Surround Sound: A Chance for Enhanced Creativity   540

DEPARTMENTS

News of the Sections   542
Sound Track   546
New Products and Developments   548
Available Literature   549
Advertiser Internet Directory   549
Upcoming Meetings   550
Membership Information   551
Sections Contacts Directory   560
AES Conventions and Conferences   568

FPO For the cover:

2006 June, Volume 54 Number 6

spine: 2006 June, Volume 54 Number 6