|VOLUME 45 NUMBER 5 1997 May|
President's Message - The AES: The Voice of Technical Leadership
Elizabeth A. Cohen 315
Hybrid Sampling-Wavetable Synthesis with Genetic Algorithms
Jennifer Yuen and Andrew Horner 316
A combination of hybrid sampling and wavetable synthesis for matching acoustic instruments is demonstrated using genetic algorithm optimization. Tone sampling is used for the critical attack portion and wavetable synthesis is used to match the more gradually changing sustain and decay. A hybrid sampling wavetable performs a smooth crossfade transition. This method has been used to synthesize piano, harp, glockenspiel, and temple block tones.
Measurement of Directional Scattering Coefficients Using Near-Field Acoustic Holography and Spatial Transformation of Sound Fields
Mendel Kleiner, Hans Gustafsson, and Joakim Backman 331
Near-field holography is used to measure the sound field above the surface of an acoustical scatterer. The scattered sound field is then spatially transformed to the desired distance and angle; the angle corresponds to a specific angle relative to the surface normal. This method can predict the sound field at close distances to the scattering object, while the data storage requirement is smaller than conventional polar response measurements.
Fundamentals of Diffraction
J. R. Wright 347
Basic theoretical and practical analysis has been performed to clarify the physical attributes of diffraction. Using finite element analysis (FEA) simple measurements corroborate the evidence of this study. Several methods are used to illustrate the diffraction effect. The author suggests that further detailed physical understanding of the diffraction mechanism is still desired.
Optimizing the Voice-Coil-Airgap Geometry for Maximum Loudspeaker Motor Strength
Carlo Zuccatti 357
The strength of a loudspeaker motor can be optimized by designing a voice coil that overhangs slightly the magnetic field gap. The stray field at the gap's edge can be engaged additionally toincrease the overall strength of the motor force.
STANDARDS AND INFORMATION DOCUMENTS
AES standard for audio preservation and restoration - Method for estimating life expectancy of compact discs (CD-ROM), based on effects of temperature and relative humidity 360
AES Standards Committee News 379
Internet subcommittee formation; SC-02, SC-04, and SC-05 meeting reports
102nd Convention Report 386
Program 4028th Regional Convention, Tokyo, Japan: Preview (insert)