3-D Sound for Virtual Reality and Multimedia
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NASA/TM—2000–000000 3-D Sound for Virtual Reality and Multimedia Durand R. Begault Ames Research Center, Moffett Field, California April 2000 The NASA STI Program Office ... in Profile Since its founding, NASA has been dedicated to · CONFERENCE PUBLICATION. the advancement of aeronautics and space Collected papers from scientific and science. The NASA Scientific and Technical technical conferences, symposia, Information (STI) Program Office plays a key seminars, or other meetings sponsored part in helping NASA maintain this important or co-sponsored by NASA. role. · SPECIAL PUBLICATION. 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NASA counterpart of peer-reviewed formal · E-mail your question via the Internet to professional papers, but having less [email protected] stringent limitations on manuscript length and extent of graphic presentations. · Fax your question to the NASA STI Help Desk at (301) 621-0134 · TECHNICAL MEMORANDUM. Scientific and technical findings that are · Telephone the NASA STI Help Desk at preliminary or of specialized interest, e.g., (301) 621-0390 quick release reports, working papers, and bibliographies that contain minimal · Write to: annotation. Does not contain extensive NASA STI Help Desk analysis. NASA Center for AeroSpace Information · CONTRACTOR REPORT. Scientific and 7121 Standard Drive technical findings by NASA-sponsored Hanover, MD 21076-1320 contractors and grantees. NASA/TM—2000–000000 3-D Sound for Virtual Reality and Multimedia Durand R. Begault Ames Research Center, Moffett Field, California National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035 April 2000 Acknowledgments Without the assistance and support of Justine, Pat, Denise, Chloe, Nigel, tre, Bill, Lars, Joel, Rick, Dr. B, Jenifer, Reuben, and many others, the completion of this book would not have been possible. About the Cover Cylindrical Surface Plot of the Head-Related Transfer Function: Magnitude Response as a Function of Frequency over Azimuth Angle on a Radial Axis, by William Martens of E-mu/Creative Technology Center. The cover photograph shows a visualization of the magnitude response (gain) of the head-related transfer function (HRTF) measured at the eardrum position of the anthropomorphic mannequin KEMAR. HRTFs were measured for 19 loudspeaker directions circling the side of the head facing the loudspeaker placed at ear level. The surface was constructed by interpolating the gain within each of 50 log-spaced frequency bands for the 19 HRTFs using a bicubic spline. The lowest band was centered on 55 Hz, the highest on 21,331 Hz. The distance of the surface from the origin and the color indicates the gain at a particular frequency and azimuth, which ranges from blue-black at the lowest gain (-43.9 dB) to a desaturated yellow at the peak gain (14.6 dB). Available from: NASA Center for AeroSpace Information National Technical Information Service 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076-1320 Springfield, VA 22161 301-621-0390 703-605-6000 Table of Contents Preface to the NASA Technical Memorandum version...................................................................ix Preface..............................................................................................................................................x Overview......................................................................................................................................xii CHAPTER ONE..............................................................................................................................1 Virtual Auditory Space: Context, Acoustics, and Psychoacoustics..................................................1 Context..........................................................................................................................................1 Source-Medium-Receiver Model: Natural versus Virtual Spatial Hearing........................................4 Application Types.............................................................................................................................7 Virtual Audio: A Special Case......................................................................................................11 Components.................................................................................................................................12 So What Is 3-D Sound Good For?................................................................................................13 Surround versus 3-D Sound.........................................................................................................16 Characteristics of Sound Sources....................................................................................................17 Describing Waveforms.................................................................................................................17 Periodic and Aperiodic Waveforms..............................................................................................17 Digital Sound and Signal Processing............................................................................................20 Harmonics...................................................................................................................................20 Fourier Analysis...........................................................................................................................21 Amplitude Envelope....................................................................................................................25 Perception.......................................................................................................................................25 Psychoacoustics and Applications................................................................................................25 Perceptual Correlates of Frequency, Intensity, and Spectral Content.............................................27 Cognition.....................................................................................................................................29 CHAPTER TWO...........................................................................................................................31 Overview of Spatial Hearing Part I: Azimuth and Elevation Perception.....................................31 Interaural Time and Intensity Cues...............................................................................................31 Lateralization...........................................................................................................................31 Physical Basis of Lateralization................................................................................................32 ITD Envelope Cue....................................................................................................................33 Perception of Lateralization.....................................................................................................34 The Precedence Effect.................................................................................................................36 ITD, IID, and Barn Owls: A Neurological Processing Model.........................................................37 Head Movement and Source Movement Cues................................................................................39 Head Movement...........................................................................................................................39 Moving Sound Sources................................................................................................................40 Spectral Cues Provided by the Pinnae............................................................................................40 Ambiguous ITD and IID Cues.....................................................................................................40 The Head-Related Transfer Function............................................................................................41 A Do-It-Yourself Experiment with Spectral