2008 March, Volume 56 Number 3

CONTENTS

PAPERS

Digital Audio Antiquing—Signal Processing Methods for Imitating the Sound Quality of Historical Recordings
Vesa Välimäki, Sira González, Ossi Kimmelma, and Jukka Parviainen   115
Processing modern audio files to make them appear to have originated from historic technology, called antiquing, is the inverse of restoring old recordings. Simulating both global and local degradations of older technologies can be useful in such applications as testing restoration algorithms. A theoretical analysis of old recordings combined with numerous case studies results in a convincing imitation of historic phonograph and gramophone recordings. This work was motivated by a museum that wanted to show how audio technology has evolved over the last 150 years.

Evaluation of HE-ACC, AC-3, and E-AC-3 Codecs
Leslie Gaston and Richard Sanders   140
A carefully controlled independent double-blind test with 27 listeners compared the Dolby Digital AC-3 standard compression codec with newer bandwidth extended codecs, Advanced Audio Coding Plus HE-AAC and Dolby Digital Plus E-AC-3. Subjective tests of this kind require a listening space that is physically and acoustically appropriate for detecting auditory nuances, mostly conforming to the standards of ITU-R BS.1116-1. Out of a large library of samples, a subset was selected based on their ability to challenge compression codecs. On average, AC-3 sounded better than the other two codecs.

Sound Field Analysis along a Circle and Its Applications to HRTF Interpolation
Thibaut Ajdler, Christof Faller, Luciano Sbaiz, and Martin Vetterli   156
The sampling and interpolation of the sound field along a circle is studied, and an angular sampling theorem is presented. Application of these results can be found in the problem of interpolating coarsely sampled head-related transfer functions (HRTFs). The proposed method interpolates HRTFs in a sub-band domain. For the low temporal frequencies satisfying the sampling theorem, HRTFs can be interpolated very precisely. At higher frequencies, the angular interpolation is carried out in a complex temporal envelope domain to limit aliasing. Numerical simulations indicate that the proposed method performs better in a mean square error sense than conventional interpolation methods.

A New Method for Measuring Distortion Using a Multitone Stimulus and Noncoherence
Steve Temme and Pascal Brunet   176
A new approach for measuring distortion provides a continuous distortion curve versus frequency, and the method is suitable for use with noise, music, and multitone stimuli. Distortion measures are derived from dual-channel analysis of the noncoherence between the stimulus and the response. The mathematics is based on Volterra theory, which is an extension of linear system theory but applied to nonlinear systems. Because the technique uses standard signal processing, the approach is simple, accurate, and repeatable.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   189
Audio metadata; evaluation of loudspeakers; audio file exchange

FEATURES

124th Convention Preview, Amsterdam   194
     Exhibit Previews   196
Forensic Audio Analysis   Francis Rumsey   211
125th Convention, San Francisco, Call for Papers   231

DEPARTMENTS

News of the Sections   217
Sound Track   222
Available Literature   223
Membership Information   226
Upcoming Meetings   228
Advertiser Internet Directory   229
Sections Contacts Directory   232
AES Conventions and Conferences   240

FPO For the cover:

2008 March, Volume 56 Number 3

spine: 2008 March, Volume 56 Number 3