2008 June, Volume 56 Number 6

CONTENTS

PAPERS

On Some Biases Encountered in Modern Audio Quality Listening Tests—A Review
S⁄lawomir Zieli´nski, Francis Rumsey, and Søren Bech   427
A careful evaluation of listening tests designed to measure audio quality shows that they are vulnerable to systematic errors, which include biases due to affective judgments, response mapping bias, and interface bias. As a result of factors such as personal preferences, the appearance of the equipment, and the listeners’ expectations or mood, errors can range up to 40% with respect to the total range of the scale. As a general conclusion, test results should be considered relative, rather than absolute. Scales in previous studies, which have been assumed to be linear, may exhibit departure from linearity. The visual appearance of the user interface may lead to severe quantization of the distribution of scores. Recommendations are offered to improve audio quality tests.

Binaural Loudness for Artificial-Head Measurements in Directional Sound Fields
Ville Pekka Sivonen and Wolfgang Ellermeier   452
The effect of the angle of incidences in the horizontal plane influences the perceived loudness of a sound field. In binaural listening, the experience of loudness requires two signals to be combined, each of which has been changed by head shadowing. This research provides a model based on power summation for predicting binaural loudness using artificial-head measurements. In subjective listening tests, there were no statistically significant differences between naive and expert listeners.

Mechanical Resonances and Geometrical Nonlinearities in Electrodynamic Loudspeakers
Nicolas Quaegebeur and Antoine Chaigne   462
A method for analyzing the nonlinear behavior of loudspeakers, which includes the effects of modal resonances and geometrical nonlinearities, results in a model without regard to the kind of nonlinearity. This state–space approach is equally valid for a single degree of freedom (plane wave piston) and higher order degrees, including “break-up” modes of vibration. For a classical loudspeaker, consistency between predicted and measured results across the audible range validates the method. Nonlinearities are observed near resonance frequencies and at their submultiples.

Virtual Sound Source Rendering Using a Multipole-Expansion and Method-of-Moments Approach
Jens Hannemann and Kevin D. Donohue   473
Using an arbitrary arrangement of loudspeakers, a novel method for rendering audio signals can create virtual and immersive environments. By emphasizing a small sweet spot, unlike the more popular wavefield synthesis (WFS), this method renders virtual sources in a small area around a single listener, which significantly reduces the number of loudspeakers required for comparable performance. A standard personal computer is able to run the computationally efficient algorithm in real time. An example demonstrates a tone moving through the listener’s environment.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   482
Audio-file transfer and exchange

FEATURES

34th Conference Preview, Jeju Island, Korea   484
     Calendar   487
     Program   488
If It’s Loud, Does That Mean It’s Bad?   Francis Rumsey   493
35th Conference, London, Call for Papers   518

DEPARTMENTS

Upcoming Meetings   498
News of the Sections   499
Sound Track   505
New Products and Developments   506
Membership Information   508
Advertiser Internet Directory   509
Sections Contacts Directory   520
AES Conventions and Conferences   528

FPO For the cover:

2008 June, Volume 56 Number 6

spine: 2008 June, Volume 56 Number 6