2007 March, Volume 55 Number 3

CONTENTS

PAPERS

On the Audibility of All-Pass Phase in Electroacoustical Transfer Functions
Henrik Møller, Pauli Minnaar, Søren Krarup Olesen, Flemming Christensen, and Jan Plogsties   115
A study of second-order all-pass filters at 1-12 kHz shows that phase shift can result in a perception of "ringing" or "pitchiness." This happens for decay time constants in the impulse response of more than 0.8 ms, which is equivalent to a group delay peak of 1.6 ms. Although these thresholds resulted when using artificial impulse sounds, similar results can be expected from worst-case audio signals. Audibility is reduced, though, with more typical audio, such as music. All-pass sections in the signal path to only one ear, such as in binaural synthesis, result in a lateral shift of the auditory image.

A Digital Plate Reverberation Algorithm
Stefan Bilbao   135
Most classical digital artificial reverberation techniques are based around perceptually motivated building blocks, such as all-pass or feedback delay networks, or convolution with recorded impulse responses. Computing power is now considerable, and full physical simulation is possible in some cases, such as plate reverberation. A digital simulation generates all the richness of the real-world plate reverb, with much additional flexibility, in terms of damping rates, multiple channel input/output, choice of material, and tensioning.

ENGINEERING REPORTS

Multiband Audio Processing and Its Influence on the Coverage Area of FM Stereo Transmission
Oscar Bonello   145
A more careful analysis of the effect of digital audio processing in FM broadcasting shows that the empirical intuition of broadcasters is consistent with the theory. Multiband compression techniques not only increase the loudness of the received signal, but also increase the coverage area if the system is stereophonic. The L-R side channel in FM stereo is essentially an AM process, and it is well known that the coverage area for AM depends on the modulation level.

Multichannel Audio Processing Using a Unified-Domain Representation
Kevin M. Short, Ricardo A. Garcia, and Michelle L. Daniels   156
As multichannel audio becomes more prevalent, alternative representations of the composite signal offer different kinds of flexibility. In a unified-domain representation, the audio signal is represented as a one-dimensional magnitude vector, where each component is multiplied by a complex matrix that encodes the spatial and phase relationship of each channel. By separating the intensity from the spatial information, different transformations can be applied without disturbing the synchronous relationship of the signals in each channel. Taking advantage of spatial masking is one obvious application of this representation.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   167
Personal computer audio measurements; multiple media storage environment; polarity; loudspeaker patch panels; acoustic surface scattering uniformity; sound source modeling; grounding and EMC practices

FEATURES

122nd Convention Preview, Vienna   170
     Exhibit Previews   172
Reverberation and Dereverberation   189
123rd Convention, New York, Call for Papers   215

DEPARTMENTS

AES Awards   178
News of the Sections   195
Sound Track   199
Available Literature   202
Upcoming Meetings   203
Membership Information   204
Advertiser Internet Directory   205
Sections Contacts Directory   216
AES Conventions and Conferences   224

FPO For the cover:

2007 March, Volume 55 Number 3

spine: 2007 March, Volume 55 Number 3