|VOLUME 48 NUMBER 4 2000 APRIL|
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
Nick Zacharov 317
STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News Audio file exchange medium; digital interfaces 322
108th Convention Report, Paris 326
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
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
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VOLUME 48 NUMBER 4 2000 APRIL
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