Tuesday, October 8 1:00 pm – 4:00 pm
SESSION N; PSYCHOACOUSTICS, PART 2

Chair: Nick Zacharov, Nokia Research Center, Tampere, Finland

N-1 Industry Evaluation of In-Band On-Channel Digital Audio Broadcast Systems—David Wilson, Consumer Electronics Association, Arlington, VA, USA

The National Radio Systems Committee’s testing and evaluation program for in-band on-channel digital audio broadcast systems is described. The results of laboratory and field tests performed during 2001 on iBiquity Digital Corporation’s AM-band and FM-band IBOC DAB systems are reported. The conclusions drawn from the laboratory and field test results are also reported, and implications for the future are discussed.
Convention Paper 5709

N-2 Comparisons of De Facto and MPEG Standard Audio Codecs in Sound Quality—Eunmi L. Oh, JungHoe Kim, Samsung Advanced Institute of Technology, Suwon, Korea

The current paper is concerned with assessing the sound quality of various audio codecs including ubiquitous de facto standards. Formal listening tests were conducted based on the ITU-R Recommendation BS.1116 in order to provide an objective measure of sound quality. Codecs tested included de facto standards that were commercially and non-commercially available and the MPEG general audio. In addition, our recently updated codec was tested. Test items consisted of usual MPEG test sequences and other sensitive sound excerpts at the bit rate of 64- and 96-kb/s stereo. Experimental results show that the sound quality of our newest codec out paces that of most of other codecs.
Convention Paper 5710

N-3 Evaluating Digital Audio Artifacts with PEAQ—Eric Benjamin, Dolby Laboratories, San Francisco, CA, USA

Portions of the digital audio chain have been incrementally improved by development, such that objective specifications indicate a very high level of performance. Subjective reviews of these components often claim to observe substantial differences between products. This investigation uses the tool PEAQ (perceptual evaluation of audio quality) to measure the audio degradation caused by analog to digital converters, digital to analog converters, and sample rate conversion, and also to measure the minute incremental changes of codec audio quality that accompany very small changes in data rate.
Convention Paper 5711

N-4 The Use of Head-and-Torso Models for Improved Spatial Sound Synthesis—V. Ralph Algazi, Richard O. Duda, Dennis M. Thompson, University of California, Davis, CA, USA

This paper concerns the use of a simple head-and-torso model to correct deficiencies in the low-frequency behavior of experimentally measured head-related transfer functions (HRTFs). This so-called snowman model consists of a spherical head located above a spherical torso. In addition to providing improved low-frequency response for music reproduction, the model provides the major low-frequency localization cues, including cues for low-elevation as well as high-elevation sources. The model HRTF and the measured HRTF can be easily combined by using the phase response of the model at all frequencies and by cross-fading between the dB magnitude responses of the model and the measurements. For efficient implementation, the exact snowman HRTF is approximated by two time delays and two first-order IIR filters. Because the poles are independent of the location of the virtual source, this supports a simple real-time implementation that allows for arbitrarily rapid head and source motion.
Convention Paper 5712

N-5 Three-Dimensional Headphone Sound Reproduction Based on Active Noise Cancellation—Daniël Schobben, Ronald Aarts, Philips Research Labortories, Eindhoven, The Netherlands

Headphone signal processing systems that are commercially available today are not optimized for the individual listener. This results in large localization errors for most listeners. In this paper a system is introduced that requires a one-time calibration procedure, which can be carried out conveniently by the listener. This system consists of conventional headphones into which small microphones have been mounted. An active noise cancellation method is used to achieve a sound reproduction via headphones, which is as close as possible to a reference loudspeaker setup. The active noise cancellation system is based on adaptive filters that are implemented in the frequency domain.
Convention Paper 5713

N-6 On the Design of Canonical Sound Localization Environments—Eric J. Angel, Ralph Algazi, Richard O. Duda, University of California, Davis, CA, USA

This paper addresses the design of virtual auditory spaces that optimize the localization of sound sources under engineering constraints. Such a design incorporates some critical cues commonly provided by rooms and by head motion. Different designs are evaluated by psychoacoustics tests with several subjects. Localization accuracy is measured by the azimuth and elevation errors and the front/back confusion rate. We present a methodology and results for some simple canonical environments that optimize the localization of sounds.
Convention Paper 5714