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Session P Tuesday, May 15 13:30 - 18:00 hr Room C/D

Psychoacoustics, Perception and Listening Tests, Part 2

Chair: Sean Olive, Harman International, Northridge, CA, USA

13:30 hr P-1
Detection Threshold for Tones above 22kHz
Kaoru Ashihara & Shogo Kiryu
Electrotechnical Laboratory, Tsukuba, Japan

To investigate audibility of ultrasounds contained in a complex tone, psycho-acoustic experiments were designed. Human subjects were required to discriminate stimuli with and without components above 22kHz. All subjects distinguished between sounds with and without ultrasounds only when the stimulus was presented through a single loudspeaker. When the stimulus was divided into six bands of frequencies and presented through 6 loudspeakers in order to reduce intermodulation distortions, no subject could detect any ultrasounds. It was concluded that addition of ultrasounds might affect sound impression by means of some non-linear interaction that might occur in the loudspeakers.
Paper 5401

14:00 hr P-2
Coloration of Amplitude-Panned Virtual Sources
Ville Pulkki
Helsinki University of Technology, Espoo, Finland

The coloration of amplitude-panned virtual sources is studied with listening tests and with auditory modeling for anechoic and reverberant listening. It is found that the amplitude panning produces a comb-filter effect that is audible in anechoic listening. When the listening room is reverberant, the effect is less audible depending on the amount of reverberation. The coloration of a virtual source is dependent on the number of loudspeakers used to generate it, and it is also dependent on the locations of loudspeakers.
Paper 5402

14:30 hr P-3
The Use of Multidimensional Scaling Techniques in Subjective Testing of Sound Quality
Douglas McKinnie & Francis Rumsey
University of Surrey, Guildford, UK

The need for measures of overall audio quality is becoming increasingly clear, as is the realization that audio quality is itself multidimensional in nature. A research design for subjective listening tests is presented which uses multidimensional scaling of preference judgments. The task for the listener is greatly simplified in comparison to scaling of multiple attributes, yet MDS techniques can reveal both the underlying perceptually relevant dimensions of the stimuli under test and a unidimensional quality rating in the form of proximity to an ideal point in the model space. Examples from the authorsí research illustrate these points.
Printed Paper not available

15:00 hr P-4
Uses and Misuses of Psychophysical Methods in the Evaluation of Spatial Sound Reproduction
William Martens
University of Aizu, Aizu-Wakamatsu, Japan

Whereas the primary motivation in spatial hearing research has been to gain greater understanding of the mechanisms of human spatial hearing, the motivation for applied research has been the verification and validation of various spatial audio rendering technologies under development. This paper outlines some of the uses and misuses of psychophysical methods typically employed in the subjective evaluation of spatial sound reproduction. The emphasis is upon the essential tension between engineering goals and scientific goals, which, while often conflicting, serve to focus psychophysical research upon resolving disputes between rival theories of how best to simulate spatial sound fields for a human listener.
Paper 5403

15:30 hr P-5
Recognition of Everyday Auditory Scenes: Potentials, Latencies and Cues
Vesa Peltonen, Anssi Klapuri, Antti Eronen & Mikko Parviainen
Tampere University of Technology, Tampere, Finland

A listening test was conducted where the human abilities in recognizing everyday auditory scenes based on binaural recordings were studied. The accuracy, latency, and acoustic cues used by the subjects in the recognition process were analyzed. The average correct recognition rate for 19 subjects was 70% for 25 different scenes, and the average recognition time was 20 seconds. In most cases, the test subjects reported that the recognition was based on prominent identified sound events.
Paper 5404

16:00 hr P-6
GLS - A Generalized Listener Selection Procedure
Ville-Veikko Mattila & Nick Zacharov
Nokia Research Center, Tampere, Finland

The need to perform subjective evaluations of audio is forever present. Such techniques are known to be inefficient and prone to unreliability. This can be partially overcome by using so-called expert as opposed to naive listeners. Expertise is addressed in some depth to clarify its meaning and to illustrate the benefits in terms of reliability and repeatability of listening tests. The generalized listener selection (GLS) procedure is presented for establishing permanent expert listening panels for a wide range of subjective tests. The method allows for the rapid selection and assessment of listeners based upon a number of criteria. Correct sampling of the population is achieved by an assessment of on-line questionnaires, followed by an audiometric evaluation. The last stage of the GLS procedure consists of three listening tests, identical in structure, designed to evaluate the discrimination skills and reliability of subjects. Means for the assessment of both intra-rater reliability and inter-rater agreement are presented.
Paper 5405

16:30 hr P-7
Perceptual (Ir)relevance of HRTF Magnitude and Phase Spectra
Jeroen Breebaart (1) & Armin Kohlrausch (2)
IPO Center for User-System Interaction, Eindhoven, The Netherlands
Philips Research Laboratories, Eindhoven, The Netherlands

This paper discusses the perceptual consequences of smoothing of anechoic HRTF phase and magnitude spectra. The smoothing process is based on a binaural perception model, in which interaural cues in the auditory system are rendered at a limited spectral resolution. This limited resolution is the result of the filter bank present in the peripheral auditory system (i.e. the cochlea). Listening tests with single and multiple virtual sound sources revealed that both the phase and magnitude spectra of HRTFs can be smoothed with a gamma-tone filter which equals estimates of the spectral resolution of the cochlea without audible artifacts. The amount of smoothing was then increased by decreasing the order of the gamma-tone filters. If the filter order is reduced by a factor 3, subjects indicate spectral and positional changes in the virtual sound sources. The binaural detection model developed by Breebaart, van de Par and Kohlrausch was used to predict the audibility of the smoothing process. A comparison between model predictions and experimental data showed that the threshold at which subjects start to hear smoothing artifacts can be predicted accurately. Moreover, a high correlation exists between the model output and the amount of stimulus degradation reported by subjects.
Paper 5406

17:00 hr P-8
Progress in Perceptual Transfer Function Measurement - Tonal Balance
David Clark
DLC Design, Wixom, MI, USA

Measured data from over 150 automotive sound systems is compared to subjective assessment of music tonal balance for the same systems. The trained listeners assessed a set of sub-attributes of tonal balance, such as peakiness and frequency extension using music source material. Listening was always completed before measurements were made. The measured data was analyzed by a corresponding set of technical sub-attributes. Encouraging correlation was found between aspects of measured and perceived tonal balance.
Paper 5407

17:30 hr P-9
Development of an Engineering Application for Subjective Evaluation of Human Response to Noise
Charalampos Dimoulas, George Kalliris, George Papanikolaou, Dimitris Christidis & Christos Sevastiadis
Aristotle University of Thessaloniki, Thessaloniki, Greece

This work focuses on the design and implementation of a computerized psycho-physiological monitoring engineering system that detects human responses to environmental noises. Classical human stimulus monitoring analysis tools were used to treat human bodily response under the presence of annoying noises. Applicable sound recording and reinforcement equipment were selected and employed to accurately simulate environmental noise conditions. A computerized data acquisition and analysis system was designed and developed. Some first results have been obtained and are currently analyzed.
Paper 5408


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