VOLUME 48 NUMBER 4 2000 APRIL

CONTENT

PAPERS

Generalized Fractional-Octave Smoothing of Audio and Acoustic Responses
Panagiotis D. Hatziantoniou and John N. Mourjopoulos 259

Fractional-octave smoothing methods can be implemented on measured response functions of audio-electroacoustic-acoustic systems, which can be complemented by a generalized mathematical framework for smoothing the complex transfer function response. Appropriately modified impulse response functions can also be derived. This additional time-domain information can be useful in many audio engineering applications because it results in functions of reduced complexity while retaining the system's initial transient and perceptual attributes.

Digital Equalizer Coefficient Generation Techniques
R. J. Clark, E. C. Ifeachor, G. M. Rogers, and P. W. J. Van Eetvelt 281

Techniques for calculating digital coefficients for discrete-time audio equalizers are examined with close consideration given to minimizing filter response distortion and the size of the computational load for on-line calculation. Offset and image distortion correction methods are developed to improve the matched z transform (MZT) response distortion. Prewarping the peak gain in the MZT distortion results in an affordable computational increase while improving the response, stability, and noise characteristics of the resulting filters. The effects of the new emerging higher sampling rates and their influence on coefficient transforms are also explored.

Estimates of Nonlinear Distortion in Feedback Amplifiers
Edward M. Cherry 299

Estimates of nonlinear distortion in feedback amplifiers can be characterized by two generators at the input-one voltage and one current. These generators represent the negatives of the voltage and current antidistortion, which, when added to their respective input voltage and current sources, reduce the distortion at the output of the amplifier system to zero. This method predicts harmonic and intermodulation products for practical amplifiers and provides design techniques for reducing distortion.

LETTERS TO THE EDITOR

Comments on "Subjective Appraisal of Loudspeaker Directivity for Multichannel Reproduction"
Tomlinson Holman 314

Author's Reply
Nick Zacharov 317

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News Audio file exchange medium; digital interfaces 322

FEATURES

108th Convention Report, Paris 326

Exhibitors 344

Program 347

Updates and Corrections to the 1998/1999 International Sections Directory 367

Updates to Review of Society's Sustaining Members 371

AES News: Historical Committee Projects Move Forward 377

DEPARTMENTS

News of the Sections 372

Upcoming Meetings 376

Sound Track 378

New Products and Developments 379

Available Literature 381

Membership Information 382

Advertiser Internet Directory 383

In Memoriam 385

Sections Contacts Directory 386

AES Conventions and Conferences 392

FPOFor the cover:

VOLUME 48 NUMBER 4 2000 APRIL

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