|1998 June, VOLUME 46 NUMBER 6|
Direct Feedback Linearization of Nonlinear Loudspeaker Systems
Wolfgang Klippel 499
Nonlinear loudspeaker system linearization that uses the control law in the direct form makes audio signal prefiltering in state feedback linearization redundant. The computation complexity is thereby reduced, while requiring fewer loudspeaker parameters than feedback controllers using the integrator-decoupled configuration.
Improving Loudspeaker Performance for Active Noise Control Applications
Steven A. Lane and Robert L. Clark 508
Active noise and acoustic control rely on the performance of actuators, which are most often loudspeakers. The loudspeaker's performance can be enhanced for applications such as control of acoustic enclosures by compensating a loudspeaker with a technique similar to motional feedback. A method is demonstrated that approximates constant volume velocity behavior over the piston mode frequency range of the transducer, which decouples the actuator from the system being controlled. This scheme reduces the impact of the loudspeaker dynamics over the control bandwidth.
Virtual Acoustics, Aeronautics, and Communications
Durand R. Begault 520
An optimal approach to auditory display designs to improve flight safety for commercial aircraft operation is reviewed. Spatialized audio techniques and active noise cancellation are the basis for improved communications conditions. The implications of hearing loss among pilots is also considered in this study. The results were obtained from flight simulator studies that were conducted at the NASA Ames Research Center.
Head-Related Transfer Function Modeling in 3-D Sound Systems with Genetic Algorithms
Ngai-Man Cheung, Steven Trautmann, and Andrew Horner 531
Practical implementations of three-dimensional (3-D) audio must take into account a large set of head-related transfer functions (HRTFs) for different azimuth and elevation angles, since the HRTFs vary as a function of relative sound source locations and subjects' attributes. In this report a genetic algorithm is used to find suitable parameters that represent the individual HRTFs at various azimuth and elevation angles. Experimental results suggest that genetic algorithms provide an effective approximation to this data reduction problem.
STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News 540
Symbols report erratum; audio-file transfer; synchronization
104th Convention Report, Amsterdam, The Netherlands 546
AES 16th International Conference, Rovaniemi, Finland, Call for Papers 601
Review of Acoustical Patents 542
News of the Sections 589
Sound Track 592
Upcoming Meetings 593
New Products and Developments 593
Available Literature 595
Membership Information 596
In Memoriam 599
Sections Contacts Directory 603
AES Conventions and Conferences 608