2004 April, Volume 52 Number 4

CONTENT

President's Message
Ron Streicher   331

PAPERS

Graphing, Interpretation, and Comparison of Results of Loudspeaker Nonlinear Distortion Measurements
Alexander Voishvillo, Alexander Terekhov, Eugene Czerwinski, and Sergei Alexandrov   332
For loudspeaker nonlinearity, measurement techniques range from single-tone harmonic distortion, which is easy to interpret but not indicative of performance with music, to reactions to multitone stimuli, which are hard to interpret but highly informative. Because multitone techniques have the potential to predict the perception of nonlinearities, the authors focus on various presentation formats and analysis techniques to make the relevant information in the thousands of intermodulation products accessible and meaningful.

ENGINEERING REPORTS

Impedance Compensation Networks for the Lossy Voice-Coil Inductance of Loudspeaker Drivers
W. Marshall Leach, Jr.   358
The high-frequency rise in the voice-coil impedance of a loudspeaker driver produced by lossy voice-coil inductance can be approximately cancelled by a Zobel network connected in parallel. Such networks improve performance by presenting purely resistive impedance to the crossover network. Although higher order networks can be used, a pair of resistors and capacitors is sufficient for typical drivers.

Scalable, Content-Based Audio Identification by Multiple Independent Psychoacoustic Matching
Geoff R. Schmidt and Matthew K. Belmonte   366
A software audio search system, as an analog to text searching, allows a target music sample to be identified by matching it to a database containing an inventory of reference samples. Rather than rely on autonomous metadata, the algorithm uses a sequence of vectors based on perceptual attributes. By iteratively testing a progression of such vectors, the algorithm has the ability to trade accuracy versus compute time. With increasing storage capacity to hold virtually unlimited quantities of audio data, an efficient search algorithm is a necessity.

On the Detection of Melodic Pitch in a Percussive Background
Preeti Rao and Saurabh Shandilya   378
Although many pitch detection algorithms have been proposed over the years, the problem is particularly difficult when melodic instruments are accompanied by percussive background. The authors propose a temporal autocorrelation pitch detector motivated by an auditory model that attempts to suppress errors produced by inharmonic interfering partials of such instruments as a kick drum. Separate processing of frequency channels proved crucial in reducing the distortion products, due to the nonlinear hair-cell model, between the signal harmonics and the interfering partials.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   392
New AESSC chairman; audio file interchange; audio over IEEE 1394

FEATURES

25th Conference Preview, London   402
    Calendar   404
    Program   405
    Registration Form   411

Historical Perspectives and Technology Overview of Loudspeakers for Sound Reinforcement
J. Eargle and M. Gander   412

DSP in Loudspeakers   434

Surround Live Summary
Frederick Ampel   440

26th Conference, Baarn, Call for Papers   457

DEPARTMENTS

Review of Acoustical Patents   395
News of the Sections   443
Upcoming Meetings   447
Sound Track   448
New Products and Developments   449
Available Literature   450
Membership Information   451
Advertiser Internet Directory   453
In Memoriam   456
Sections Contacts Directory   458
AES Conventions and Conferences   464

FPO For the cover:

2004 April, Volume 52 Number 4

spine: 2004 April, Volume 52 Number 4