| 2006 October, Volume 54 Number 10 |
CONTENTS
TUTORIALS
Tutorial: Loudspeaker Nonlinearities-Causes, Parameters, Symptoms
Wolfgang Klippel 907
This comprehensive review and tutorial discussion about nonlinear distortion in loudspeakers offers a clear perspective: under the right conditions, measurements may manifest particular nonlinear electromechanical mechanisms. Because there are a large number of such mechanisms, signals must be carefully selected to excite particular nonlinearities. A catalog of observable manifestations provides a working recipe for diagnosing defects, which then makes possible design improvement. Three examples illustrate this approach.
PAPERS
Efficient Resonant Loudspeakers with Large Form-Factor Design Freedom
Ronald M. Aarts, Joris A. M. Nieuwendijk, and Okke Ouweltjes 940
It is not possible to combine high efficiency and wide frequency bandwidth in small cabinet loudspeakers. However, by changing assumptions and allowing nonlinear electronic processing, a small loudspeaker can operate in the high-efficiency spectral region. Compressing the 2.5-octave region from 20 to 120 Hz into a narrow frequency at the natural resonances of the loudspeaker provides a means for optimizing both size and efficiency. However, acoustic quality at low frequencies is compromised. An experimental prototype illustrates the approach.
Vibrotactile Enhancement of Auditory-Induced Self-Motion and Spatial Presence
Aleksander Väljamäe, Pontus Larsson, Daniel Västfjäll, and Mendel Kleiner 954
Using cross-modal stimulation of multiple senses can enhance the illusion of motion in entertainment and virtual environments. Mechanically induced vibrations significantly improve the sense of self-motion and presence. Since vestibular excitation is not possible when not actually moving, auditory and tactile sensations can enhance an illusion of movement and presence in virtual environments. Examples of using three audio-tactile scenes illustrate the degree to which an illusion of movement is created.
ENGINEERING REPORTS
Virtual Air Guitar
Matti Karjalainen, Teemu Mäki-Patola, Aki Kanerva, and Antti Huovilainen 964
Playing a virtual guitar by tracking hand motions illustrates an approach to a natural user interface for synthesized music. Three different methods for sensing hand motion and position have been tried: data gloves in a virtual room, optical tracking of hand movement, and special control sticks that sense acceleration. Of these, optical tracking with a web camera offers the least expensive approach, since such devices are often part of a computer system. Demonstration systems at Heureka Science Center have allowed thousands of visitors to enjoy the feeling of being a rock star. Eventually, this approach may lead to the evolution of professional musical instruments.
LETTERS TO THE EDITOR
Comments on "Model Optimization of Distributed-Mode Loudspeaker Using Attached Masses"
Frank Fahy 981
Authors' Reply
Suzhen Zhang and Yong Shen 981
Comments on "Low-Frequency Optimization Using Multiple Subwoofers"
Earl R. Geddes 983
Authors' Reply
Todd Welti and Alan Devantier 984
CORRECTIONS
Corrections to "Noise Power Modulation in Dithered and Undithered High-Order Sigma-Delta Modulators"
Ivar Løkken, Anders Vinje, and Trond Sæther 985
STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News 986
Acoustics and sound-source modeling; audio connectors; grounding and EMC
FEATURES
Binaural Technology for Mobile Applications 990
New Officers 2006/2007 996
Review of Society's Sustaining Members 1001
122nd Convention, Vienna, Call for Papers 1037
31st Conference, London, Call for Papers 1038
32nd Conference, Hillerød, Call for Papers 1039
DEPARTMENTS
Reviews of Acoustical Patents 987
News of the Sections 1023
Upcoming Meetings 1026
Sound Track 1027
New Products and Developments 1030
Available Literature 1031
Membership Information 1032
Advertiser Internet Directory 1035
In Memoriam 1036
Sections Contacts Directory 1040
AES Conventions and Conferences 1048
FPO For the cover:
2006 October, Volume 54 Number 10
spine: 2006 October, Volume 54 Number 10