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Last Updated: 20070411, mei

P7 - Psychoacoustics, Perception, and Listening Tests - 1

Sunday, May 6, 09:00 — 12:00

Chair: Stefan Weinzierl

P7-1 Some Effects of the Torso on Head-Related Transfer FunctionsOle Kirkeby, Eira Seppälä, Asta Kärkkäinen, Leo Kärkkäinen, Nokia Research Center - Helsinki, Finland; Tomi Huttunen, University of Kuopio - Kuopio, Finland
A numerical method based on the ultra-weak variational formulation (UWVF) is used to calculate three sets of Head-Related Transfer Functions (HRTFs). The three sets are made by combining a hard head with a hard torso, a moderately absorbing torso, and no torso. Each set is sampled for every 50 Hz from DC to 24k Hz at 21,872 points almost evenly distributed in the far-field, thus providing a spatial resolution of approximately one degree everywhere. Since the results of the numerical simulations are not contaminated by the response of an electroacoustic chain it is possible to compare the HRTFs of a head and torso model to the HRTFs of the head only without the risk of interpreting a measurement artifact as a physical phenomenon.
Convention Paper 7030 (Purchase now)

P7-2 An Investigation into Head Movements Made When Evaluating Various Attributes of SoundChungeun Kim, Russell Mason, Tim Brookes, University of Surrey - Guildford, Surrey, UK
This paper extends the study of head movements during listening by including various listening tasks where the listeners evaluate spatial impression and timbre, in addition to the more common task of judging source location. Subjective tests were conducted in which the listeners were allowed to move their heads freely while listening to various types of sound and asked to evaluate source location, apparent source width, envelopment, and timbre. The head movements were recorded with a head tracker attached to the listener’s head. From the recorded data, the maximum range of movement, mean position and speed, and maximum speed were calculated along each axis of translational and rotational movement. The effects of various independent variables, such as the attribute being evaluated, the stimulus type, the number of repetition, and the simulated source location were examined through statistical analysis. The results showed that while there were differences between the head movements of individual subjects, across all listeners the range of movement was greatest when evaluating source width and envelopment, less when localizing sources, and least when judging timbre. In addition, the range and speed of head movement was reduced for transient signals compared to longer musical or speech phrases. Finally, in most cases for the judgment of spatial attributes, head movement was in the direction of source direction.
Convention Paper 7031 (Purchase now)

P7-3 Binaural Resynthesis for Comparative Studies of Acoustical EnvironmentsAlexander Lindau, Torben Hohn, Stefan Weinzierl, Technical University of Berlin - Berlin, Germany
A framework for comparative studies of binaurally resynthesized acoustical environments is presented. It consists of a software-controlled, automated head and torso simulator with multiple degrees of freedom, an integrated measurement device for the acquisition of binaural impulse responses in high spatial resolution, a head-tracked real-time convolution software capable to render multiple acoustic scenes at a time, and a user interface to conduct listening tests according to different test designs. Methods to optimize the measurement process are discussed, as well as different approaches to data reduction. Results of a perceptive evaluation of the system are shown, where acoustical reality and binaural resynthesis of an acoustic scene were confronted in direct A/B comparison. The framework permits, for the first time, to study the perception of a listener instantaneously relocated to different binaurally rendered acoustical scenes.
Convention Paper 7032 (Purchase now)

P7-4 Acoustic Factors of Auditory Distance Perception by the Blind While WalkingTakahiro Miura, Shuichi Ino; Teruo Muraoka, Tohru Ifukube, University of Tokyo - Tokyo, Japan
The ability by which the blind that can recognize surrounding objects solely by hearing is called "obstacle sense." By analyzing and modeling its mechanism, this model will be utilized for realizing an acoustic VR environment as well as training systems for the vision-impaired through acoustic analysis. In this paper the authors particularly focused on various sorts of acoustic factors that may contribute to perceive the distance from the subject to the obstacle especially while walking. We also investigated the factors based on the psychophysical experiments and acoustical analysis methods. In addition, the authors discussed the contribution of these factors to the blind persons’ auditory distance perception.
Convention Paper 7033 (Purchase now)

P7-5 Listener Loudspeaker Preference Ratings Obtained in situ Match those Obtained via a Binaural Room Scanning Measurement and Playback SystemSean Olive, Todd Welti, Harman International Industries, Inc. - Northridge, CA, USA; William Martens, McGill University - Montreal, Quebec, Canada
Binaural room scanning (BRS) is a method of capturing, storing, and reproducing via a head-tracking headphone display system the binaural room impulse response of one or more loudspeakers in a listening room. This paper reports the results of the first test in a series of validation tests of a custom BRS system that was developed for research and evaluation of different loudspeakers and different listening spaces. The test examined whether listeners’ loudspeaker preference ratings made in a listening room with reflective walls (in situ) were comparable to ratings made in response to BRS reproductions of those loudspeakers located in the same room. Virtually the same results were obtained in these two cases.
Convention Paper 7034 (Purchase now)

P7-6 Perceptually-Motivated Audio Morphing: BrightnessDuncan Williams, Tim Brookes, University of Surrey - Guildford, Surrey, UK
A system for morphing the brightness of two sounds independently from their other perceptual or acoustic attributes was coded, based on the spectral modeling synthesis additive/residual model. A multidimensional scaling analysis of listener responses showed that the brightness control was perceptually independent from the other controls used to adjust the morphed sound. A timbre morpher, providing perceptually meaningful controls for additional timbral attributes, can now be considered for further work.
Convention Paper 7035 (Purchase now)