Last Updated: 20050401, meiMonday, May 30, 11:30 — 13:00
Z7-1 HRTF Individualization by Solving the Least Squares Problem—Sergio G. Rodríguez, Miguel A. Ramírez, University of São Paulo - São Paulo, Brazil
The HRTF characterizes the scattering of sound waves on the human body, especially on pinnae, head, and torso; hence, it presents high variability between individuals. Given the success of recent geometrical models for the head-torso contribution to the HRTF, this paper proposes a method for modeling the pinna contribution. The model has, as entering data, specific pinna dimensions. It is able to estimate the pinna-related transfer function (PRTF) with a mean of 65% accuracy for the inter-subject PRTF variance. Since each spatial position must be modeled individually, we present here a detailed example of the method used for modeling one of them. We use HRTF and anthropometric data from the CIPIC Database.
Convention Paper 6438 (Purchase now)
Z7-2 The Effect of Nonsymmetrical Left/Right Recording Pinnae on the Perceived Externalization of Binaural Recordings—Tim Brookes, University of Surrey - Surrey, UK; Chris Treble, Technical Earth Limited - London, UK
It is known that headphone playback, even of binaurally-recorded material, often gives rise to in-the-head locatedness of reproduced sound sources. Head-tracking systems, artificial reverberation, and decorrelation of the left/right signals, have all been investigated previously as possible means by which the incidence of in-the-head locatedness may be reduced. It is proposed that the left/right symmetry of dummy-head pinnae, and of the head-related transfer functions used in binaural convolution, may exacerbate the in-the-head problem, and it is shown experimentally that, by recording using asymmetrical pinnae, perceived externalization can be increased significantly.
Convention Paper 6439 (Purchase now)
Z7-3 A Novel Objective Spatial Quality Evaluation Method for Reproduced Sound—Yu Jiao, Zhiping Zhang, Tianshu Qu, Xihong Wu, Peking University - Beijing, China
A novel objective method to evaluate localization quality of virtual sources created with sound reproduction techniques is presented. In this method, a binaural localization model is used to estimate directions of virtual sound sources. By analyzing the localization results, a quantitative evaluation of the localization performance of sound reproduction techniques is given. Virtual sources synthesized with vector-base amplitude panning (VBAP) are evaluated using this method. The results show positive agreement with subjective evaluation results in previous studies.
Convention Paper 6440 (Purchase now)
Z7-4 Objective Assessment of Spatial Localization Attributes of Surround-Sound Reproduction Systems—Martin Dewhirst, Slawomir Zielinski, Philip Jackson, Francis Rumsey, University of Surrey - Surrey, UK
A mathematical model for objective assessment of perceived spatial quality was developed for comparison across the listening area of various sound reproduction systems: mono, two-channel stereo (TCS), 3/2 stereo (5.0 surround sound), Wave Field Synthesis (WFS), and Higher Order Ambisonics (HOA). Models for mono, TCS, and 3/2 stereo are based on conventional microphone techniques and loudspeaker configurations for each system. WFS and HOA models use circular arrays of thirty-two loudspeakers, driven by signals derived from a virtual microphone array and the Fourier-Bessel spatial decomposition of the sound field respectively. Directional localization, ensemble width and ensemble envelopment of tones, extracted from binaural signals, are analyzed under a range of test conditions.
Convention Paper 6441 (Purchase now)
Z7-5 An Improved Method for Accurate Sound Localization—Akihiro Kudo, Hiroshi Higuchi, Haruhide Hokari, Shoji Shimada, Nagaoka University of Technology - Nagaoka, Niigata, Japan
When implementing out-of-head sound localization with headphones, it is well known that using head-related transfer functions (HRTFs) other than those of the listener yields degradation in sound image localization, and enhances localization error and front-back confusion. Some studies have concluded that moving the sound image eases these problems. We focus on moving sound images to achieve highly accurate localization, and propose a swing sound image method that makes the sound image swing between two locations on the horizontal plane. Listening tests verify that the proposed method greatly reduces the front-back confusion.
Convention Paper 6442 (Purchase now)
Z7-6 Head Movements: An Approach to Their Significance for Localization Tasks—Cornelius Bradter, Technische Universität Berlin - Berlin, Germany; Klaus Hobohm, Hochschule f¨r Film und Fernsehen Potsdam - Potsdam, Germany
We asked 25 test persons to locate real and virtual sound sources within a 360-degree environment. During the tasks head movements were recorded by a head tracker with a time resolution of 20 ms. We categorized the success of locating the sound sources and related the outcome to criteria deduced from the head movement data. Contrary to the assumption that stronger head movements support localization ability, we could not establish a simple relationship between head movements and good localization.
Convention Paper 6443 (Purchase now)
Z7-7 Comparison between Different Surround Reproduction Systems: ITU 5.1 versus PanAmbio 4.1—Enrico Armelloni, Paolo Martignon, Angelo Farina, University of Parma - Parma, Italy
Audio reproduction of a movie inside an undedicated room is critical; setting an ITU 5.1 system at home, for example, requires placement of a large number of speakers around the room. But the position of the speakers are often conditioned by the furniture. Bad alignment reduces spatial performances of the system dramatically. For circumventing the above problems, most stereo TV sets, nowadays, are equipped with some form of "virtual surround" reproduction, employing substantially the stereo dipole method. This provides a very good frontal sound stage, but does not match the performance of surround loudspeakers. An alternative reproduction technique is PanAmbio 4.1, based on a double stereo dipole system (frontal and rear). In this work the authors propose a comparison between the standard 5-way surround system and the new one. Validation is performed by subjective tests inside a domestic room.
Convention Paper 6444 (Purchase now)
©2005 Audio Engineering Society, Inc.