2008 July/August, Volume 56 Number 7/8

CONTENTS

Editor's Note
John Vanderkooy   531

PAPERS

Concert Hall Acoustics—2008
Leo L. Beranek   532
A comprehensive review of concert hall acoustics shows a clear relationship between measurements and perceived quality among listeners, conductors, and musicians. While the basic Sabine and Eyring equations are still important for determining reverberation times, there are other measures that are also important. These include rise and decay of sound energy, early decay at mid-frequencies, lateral fraction, binaural quality index, perceived loudness, listener envelopment, and others. These measures must be connected to the subjective ratings of concert halls that have been accumulated over the years. The principles are illustrated with case studies that compare the shoebox shape to the surround design.

Noncontact Surface Metrology for Preservation and Sound Recovery from Mechanical Sound Recordings
P. J. Boltryk, J. W. McBride, M. Hill, A. J. Nascè, Z. Zhao, and C. Maul   545
Decoding historic mechanical recordings using noncontact optical methods avoids further degradation that would be created with a stylus. Moreover, for recordings that have been damaged, contact methods do not work. The proposed method, which is based on surface metrology of engineering surfaces, measures the surface optically, while offline signal processing then recovers the audio information. The surface record, preserved as a high-resolution matrix grid, is retained indefinitely. Preliminary results indicate better noise and distortion performance compared to mechanical playback.

Automatic Musical Genre Classification Using a Flexible Approach
Jayme Garcia Arnal Barbedo and Amauri Lopes   560
An automated method for classifying music signals into genres is proposed. Up to three genres are assigned to each example along with a measure of the degree of influence. The method is based on a structure formed by taxonomy of four hierarchical layers, with 29 genres in the lowest layer and 10 target genres in the higher layers. In more than 77% of the cases there was successful classification. The computational effort is sufficiently low that this method could be used in real time.

Modeling Frequency-Dependent Boundaries as Digital Impedance Filters in FDTD and K-DWM Room Acoustics Simulations
Konrad Kowalczyk and Maarten van Walstijn   569
A novel method for modeling frequency-dependent boundaries in finite-difference time-domain (FDTD) room acoustic simulations offers a significant improvement over the conventional one-dimensional approach. The method incorporates a digital impedance filter resulting in multidimensional formulation. Reflecting sound waves approximate the theoretical reflectance for any value of wall impedance and angle of incidence, especially at low frequencies. Both phase and amplitude are preserved. Results obtained from numerical experiments confirm the validity of the approach.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   585
Digital audio measurements; digital input/output interfacing; audio-file transfer and exchange; audio applications of networks

FEATURES

124th Convention Report, Amsterdam   590
     Exhibitors   607
125th Convention Preview, San Francisco   610
     Exhibit Previews   612
Signal Processing for 3-D Audio   Francis Rumsey   640
Education News   646
35th Conference, London, Call for Papers   654
36th Conference, Dearborn, Call for Papers   655

DEPARTMENTS

News of the Sections   648
Sound Track   650
Membership Information   652
Upcoming Meetings   653
Advertiser Internet Directory   653
Sections Contacts Directory   656
AES Conventions and Conferences   664

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2008 July/August, Volume 56 Number 7/8

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