2002 May, Vol 50 Number 5

CONTENT

PAPERS

A Model of Loudness Applicable to Time-Varying Sounds
Brian R. Glasberg and Brian C. J. Moore   331
A previous model for computing the subjective loudness of steady-state sounds from their spectra has been extended to include time variations. After filtering the input signal to mimic the frequency response of the outer and middle ear, a fast Fourier transform (FFT) of the resulting signal is then used to compute an instantaneous loudness. The overall loudness uses attack and release times to convert the instantaneous loudness to the subjective experience of the listeners. The model gives good results with modulated signals over a wide range of rates.

Perception of Reverberation Time in Small Listening Rooms
T. I. Niaounakis and W. J. Davies   343
Spatial parameters, such as reverberation time, are typically used for large spaces and have not been extensively applied in a small room. This study determined that listeners' sensitivity to changes in reverberation time was on the order of 40 ms. Two methods were used: changing absorption in a real space and simulating changes from a dummy head with delay headphone reproduction.

ENGINEERING REPORTS

An IIR Synthesis Method for Plucked-String Instruments with Embedded Portamento
Alvin W. Y. Su, Wei-Chen Chang, and Rei-Wen Wang   351
The normal wavetable technique for synthesizing the portamento of plucked-string instruments, such as the ancient Chinese San-Sien, fails because of the wide frequency range. A new approach, which uses a wavetable to drive an infinite-impulse-response (IIR) filter whose coefficients have been modeled as a neural network training algorithm, provides accurate synthesis of these unusual sounds. The method assumes that the sounds are quasi-periodic, which also makes the method appropriate for certain wind instruments. Signal processing requirements are not particularly problematic.

Dipole Loudspeaker Response in Listening Rooms
James M. Kates   363
A dipole loudspeaker, which radiates sound energy from both the front and rear surfaces, appears as a velocity source, whereas the conventional monopole loudspeaker appears as a pressure source. Although the dipole loudspeaker can provide better auditory localization accuracy, it is more sensitive to room placement and angular orientation.Using a two-dimensional simulation, the author explores the importance of room response and coloration of the reproduced sounds.

LETTERS TO THE EDITOR
Comments on In Memoriam Roy Allison   375

CORRECTIONS
Correction to Content Page   375

STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News   376
Digital audio measurements; loudspeaker modeling; audio connections

FEATURES

Managing Change: The Challenge of Rights Management in the New Millennium
Keith Hill   380
Audio for Games
Martin Wilde   392
114th Convention, Amsterdam, Call for Papers   417

DEPARTMENTS

News of the Sections   397
Upcoming Meetings   401
Sound Track   402
New Products and Developments   404
Available Literature   407
Membership Information   408
Advertiser Internet Directory   410
AES Special Publications   411
In Memoriam   416
Sections Contacts Directory   418
AES Conventions and Conferences   424

FPO For the cover:

2002 May, Vol 50 Number 5

spine: 2002 May, Vol 50 Number 5