|1997 July/August, VOLUME 45 NUMBER 7/8|
President's Message: Future Technical Leadership Audible at AES Meetings Elizabeth A. Cohen 539
PAPERSFractal Wavelet Compression of Audio Signals
Robert A. Wannamaker and Edward R. Vrscay 540
Wavelet transform coding and fractal-based compression are combined in an audio signal compression technique. The signal is divided into frames that are subjected to a fast wavelet transform, with subsequent fractal coding of high-frequency coefficients using a collage approach. Modest compression ratios have been achieved, according to the authors. However, ratio increases above 6:1 should be attainable with further work.
High-Fidelity PWM-Based Amplifier Concept for Active Loudspeaker Systems with Very Low Energy Consumption
Karsten Nielsen 554
A pulse-width-modulation amplifier is described for use with woofer and midrange loudspeaker loads operating at frequencies below 4 kHz. The design is based on a new feedback topology and a bandwidth-dependent-modulation strategy, and employs a relatively low switching rate of 44.1 kHz. The power output stages exhibit excellent efficiency rates that approach 96% at high output levels.
Processing of Musical Tones Using a Combined Quadratic Polynomial-Phase Sinusoid and Residual (QUASAR) Signal Model
Yinong Ding and Xiaoshu Qian 571
The authors have developed a data reduction system for music analysis and synthesis that uses 33% less memory than previous systems while reducing the computational requirements by 50%. This novel system proposes a signal model that combines quadratic polynomial-phase sinusoids and a residual for music analysis and synthesis. The algorithm is being adapted currently to a commercially available fixed-point digital signal processor.
Precise Passive Crossover Networks Incorporating Loudspeaker Driver Parameters
A. N. Thiele 585
The author describes loudspeaker crossover design procedures that use networks to interact with the loudspeaker's electrical parameters and equalize its response into that of a second-order high-pass filter. A further network corrects the driver impedance. The equalized driver is then cascaded with a passive equalizer and a conventional ladder filter to achieve the required higher order response.
LETTERS TO THE EDITORAES Policy on World Wide Web Publication Steven Harris 595
Editor's Reply Daniel R. von Recklinghausen 595
STANDARDS AND INFORMATION DOCUMENTSAES Standards Committee News 596
103rd Convention meetings; performance loudness; mechanical media; Internet audio meeting
FEATURESAES 103rd Convention Preview: New York 602Calendar 604AES 104th Convention, Amsterdam, The Netherlands: Call for Papers 649
Exhibit Previews 610
Information for Authors of Convention Papers 651
DEPARTMENTSReview of Acoustical Patents 599
News of the Sections 637
Sound Track 642
Upcoming Meetings 644
Available Literature 644
Membership Information 646
Sections Contacts Directory 652
AES Conventions and Conferences 656