v7.0, 20040922, me

Saturday, October 30, 2:00 pm – 4:00 pm
Session Z6 Posters: PSYCHOACOUSTICS, PERCEPTION, AND LISTENING TESTS & SPATIAL PERCEPTION AND PROCESSING
NOTE: During the first 10 minutes of the session all authors will present a brief outline of their presentation.

2:00 pm
Z6-1 A Comparison of Speech Intelligibility between the Callsign Acquisition Test and the Modified Rhyme Test—Daniel Hicks, Mohan Rao, Michigan Tech University, Houghton, MI, USA; Tomasz Letowski, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, USA
The Callsign Acquisition Test (CAT) is a new speech recognition test developed by the U.S. Army to examine speech intelligibility in a military environment. This paper compared speech intelligibility results of the Callsign Acquisition Test with another test used widely in industrial applications, the Modified Rhyme Test, using listening tests and objective speech metrics. A group of 24 listeners between the ages of 18 and 25 participated in the study. Six different types of recorded background noises radiating from an armored personnel carrier; helicopter; jet engine; mid-size car; subway train; and standard pink noise were used in the study. Test results demonstrated that the differences in the mean speech recognition scores obtained for CAT and MRT across all selected background noises were not statistically significant. However, the effect of noise and interactions between the noise and the test were statistically significant. A correlation of the measured scores with the spectral content of the background noise revealed somewhat higher scores for MRT compared with CAT under selected background noises that have most of the frequency content above 500 Hz. In contrast, slightly higher scores for CAT were noticed for selected noises having predominantly low frequency components below 250 Hz.
Convention Paper 6285

2:00 pm
Z6-2 Adjustment of the Parameters Proposed for the Objective, Perceptual Based Evaluation Methods of Compressed Speech and Audio Signals—Piotr Kozlowski, Andrzej Dobrucki, Wroclaw University of Technology, Wraclaw, Poland
This document presents results of continuation of research about objective methods, which use psychoacoustics knowledge for estimation of the quality of audio signals. The software written especially for this research is presented. This program allows for implementation of the different published methods for evaluation of the quality of perceptual coded audio signals. Protocols PAQM, PSQM, NMR, PEAQ, PESQ are implemented up to now.
All of these algorithms are used for simulation of the auditory system. The software is open for the addition of new protocols as the plug-ins. There is a possibility to change and improve earlier published protocols. Authors proposed in earlier works how to improve objective protocols, e.g., by changing pitch scale. Suggested adjustment of internal parameters of signal processing, which improves results of objective evaluation, is presented. The criterion of optimization is the difference between results of subjective and objective evaluation.
Convention Paper 6286

2:00 pm
Z6-3 New Techniques Assisting Cochlear Implants Fitting—Adam Walkowiak, Institute of Physiology and Pathology of Hearing, Warsaw, Poland; Andrzej Czyzewski, Gdansk University of Technology, Gdansk, Poland; Artur Lorens, Institute of Physiology and Pathology of Hearing, Warsaw, Poland; Bozena Kostek, Institute of Physiology and Pathology of Hearing, Warsaw, Poland, Gdansk University of Technology, Gdansk, Poland
Measurement of Spread of Excitation (SoE) provides a potential method of assessment of cochlear implant users’ benefit. To provide maximum benefit for the cochlear implant users the speech processor should be fitted to the patients’ need. One objective method that could deliver important information for fitting is Neural Response Telemetry (NRT). This method helps to estimate an amplitude of electrical current that is required to elicit hearing sensation via cochlear implant. It is also possible to determine Spread of Excitation—the longitudinal spread of electrically evoked neural excitation in the cochlea, based on NRT results. The parameters of the Spread of Excitation in the individual patient may help to explain the patients’ performance and indicate in which way sound processing strategies could be modified to improve one’s benefit. In this paper measured profiles of SoE are shown and some preliminary analyses are presented.
Convention Paper 6287

2:00 pm
Z6-4 Influence of Head-Tracking to Spatial Perception—Wolfgang Hess, Ruhr-University, Bochum, Germany
To validate a head-tracking system in comparison to a loudspeaker arrangement regarding perception of auditory source width (ASW), i.e., the horizontal extension of the auditory event(s), experiments by representing narrowband and broadband noise stimuli of certain degrees of correlation were conducted. The excitation signals were presented by (i) pairs of loudspeakers and (ii) headphones with head-tracking in an anechoic environment. The evaluation by five trained subjects resulted in a good correspondence of the outcomes of the speaker and the head-tracking experiments, i.e., the head-tracking system had a negligible influence on spatial perception.
Convention Paper 6288

2:00 pm
Z6-5 Frequency Dependence of Perceptual Sound Image Distance Using Direct-to-Reverberant Ratio Control Method—Yasushige Nakayama, NHK Science & Technical Research Laboratory, Tokyo, Japan; Kaoru Watanabe, NHK, Tokyo, Japan; Satoshi Kuwata, Denon, Ltd., Fukushima, Japan
A 3-dimensional sound image controlling method is described, which controls the intensity level of sound images to arrange them near and far away from a listener (the ìcontrolî means amplitude panning for distance). The images are created with two loudspeakers arranged near and far away from the listener or with a loudspeaker array system. A subjective evaluation was performed to examine the perceptual distance of the octave band and white noise by changing the direct-to-reverberant energy ratio. It was found that the distance produced by the direct-to-reverberant energy ratio has a frequency dependency, and that the distance for more than 5,660 Hz is not significantly different when the ratio is changed. In addition, a 3-D audio coding method utilizing this result was developed. An experiment using the tool showed that the bit-rate efficiency of the method, which unifies frequency components above 5,660 Hz, can be increased by more than 30 percent compared with dual-mono transform coding, without degradation in 3-D audio reproduction.
Convention Paper 6289

2:00 pm
Z6-6 Virtual Sound Algorithm for Wide Stereo Sound Stage— Sunmin Kim, Joon Lee, SeongCheol Jang, Sangil Park, Samsung Electronics, Suwon, Korea
This paper provides a wide stereo algorithm that widens the stereo sound stage for a two-channel loudspeaker layout. The design method consists of a binaural synthesis, a crosstalk canceller, and a direct filter. This creates multiple virtual loudspeakers and allows them to spread out in the front. Consequently, the proposed algorithm, which includes the widening of the sound stage and the timbre preservation, is designed in the form of a 2-by-2 filter matrix. The filter order is minimized for easy implementation while maintaining the performance.
Convention Paper 6290

2:00 pm
Z6-7 Audio Signal Decorrelation Based on a Critical Band Approach—Maurice Bouéri, Chris Kyriakakis, University of Southern California, Los Angeles, CA, USA
This paper presents a new method for decorrelating audio signals by applying a random time shift to each critical band. The resulting signals exhibit significantly lower inter-aural cross correlation (IACC). The effects of this type of decorrelation on perceived envelopment and loss of phantom image will be presented.
Convention Paper 6291

2:00 pm
Z6-8 A Simplified Scene-Based Paradigm for Use in Training Applications—Rafael Kassier, Tim Brookes, Francis Rumsey, University of Surrey, Surrey, UK
Despite recent consumer uptake of surround sound systems and the existence of a number of studies into spatial audio attributes, there is currently no system to train listeners in the detection and discrimination of the spatial attributes of reproduced sound. Timbral ear training has been shown to increase response consistency in listening tests, but a number of obstacles must be negotiated in order to successfully implement an ear training system for spatial aspects of sound reproduction. The first of these is the determination of which spatial audio attributes are appropriate. This paper describes the formulation of a new spatial audio paradigm by testing previously documented attributes against specific selection criteria and including, modifying or rejecting them accordingly.
Convention Paper 6292