from binaural technology to virtual...
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Jens Blauert, D-Bochum
From Binaural Technology to Virtual Reality
Prominent Features of Binaural Hearing
- LocalizationFormation of positions of the auditory events(azimuth, elevation, distance, spatial extent),auditory room impression, immersion
- Suppression ofthe directional information coming from reflections(Precedence Effect, localization dominance, fusion), reverberation, coloration and noise
- Identification & segregation ofauditory streams,e.g., concurrent talkers (Cocktail-Party Effect)
Prominent Features of Binaural Hearing
- Introduction- Authentic Recording, Transmission & Reproduction- Processing & Analysis of Binaural Signals- Binaural Display & Room Simulation- Interactivity, Virtual Reality- Conclusions
From Binaural Technologyto Virtual Reality
From Binaural Technology to Virtual Reality
AuthenticReproduction
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Binaural Technology (I)Dummy-Head Designsof Different Complexity
HMS I
HMS III
KU 80 KU 81
1/8 th scale
Measuring Head-RelatedTransfer Functions (HRTFs)
- little electret microphones,inserted into the ear canals
- measuring signals are, e.g.:noise, impuls trains or sinusoids
- anechoic chamber
laserpositioncontrol
mikecable
A Set of Binaural Impulse Responses
Localization Errors with Non-optimumHRTFs
Perc
eive
dD
irect
ion
Representative HRTFs
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Parametric Modelling of the External Ear Binaural Technology (I)
Binaural Technology (IIa)
(c)
Binaural Technology (IIa)
binaural-activity display
Architecture for a Model of Binaural Hearing
Structure of theModel ofBinaural Hearing
binaural-activity map
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left < lateral deviation > right
Output of the Binaural Model: Impuls Response of a Concert Hall
critical band around 700 Hz
runn
ing
time
left < lateral deviation > right left < lateral deviation > right
Binaural Exitation Patterns of Two Different Concert Halls
Gasteig, G-Munich Musikvereinsaal, Vienna
critical band about 700 Hz, 250-ms shot
Blauert 1988
Potential Applications for Binaural AlgorithmsSuitable for Short-Term Implementation
Binaural Technology at its Best- provided that binaural signals are used
Binaural Technology (IIa)
Binaural Technology (IIb)
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Binaural Synthesis of Sound Fields in Enclosures Ray Tracing
Mirror Imaging
Binaural-Room-SimulationSystem
coarse resolution48 planes
finest resolution238 planes
medium resolution126 planes
Checking forPerceptual Authenticity inBinaural Room Simulation
Room-Acoustics&Sound-SystemsPlanning
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Interactive Systems Virtual Reality
Differences of Measured and Simulated Impulse Responses
Measuring a Pre-Set Real Environment Binaural Room Scanning (BRS)The Complete System
Head-RelatedPlay Back
Binaural Technology (IIc)
interactivity
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Experimental ParadigmPartners: Aalborg University, Denmark; Bochum University, Head Acoustics, Germany;
Pisa University, Sciencia Machinale, Italy.
The SCATIS Lab, an experimental audio/tactile interactive virtual environment
The Scenario of the SCATIS Lab
Architecturof theSCATIS-LabVirtual-RealityGenerator
Schematic of the SCATIS Lab
The SCATIS Glove SCATIS-Hardware Overviewacquired 1995
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requirements:
“smoothness”frame rate > 16/s(depending on speed ofmovements involved)
“responsiveness”delay < 60 ms
actually achievable with PCs of 2004:40 sound sources, moving at moderate speed.
frame rate 20/sdelay 20 ms
The Problem of “Realtimeability”Lehnert, 1994
List of Events Relevant to the Sound-Field Model
arrival time spectral modification HRTFs
Filter Structure for the Convolution of „Dry“ SignalsDoppler Shifts and Visibility Checkfor Moving Sound Sources
Problems in a TeleconferenceSetting
Perception of One‘s Own VoicePörschmann (2001)
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Major computational demands arise from the sound-field model whichgenerates realistic room responses, and from the aurilization enginewhich spatializes primary and reflective sounds. With today‘s PCs, up to about 200 sound sources incl. mirror sources can be handled in real time. For distributed sound sources and reverberation dedicated, computationallyeffective algorithms are usually employed.
Virtual Auditory Environments – Auditory DisplaysSome Final Statements:
Vision of a Multimodal Tele-Conferencing System
control rooms !
Generic Application Areas of Binaural Technology− a Summary −
Thank you!
[email protected]://www.ruhr-uni-bochum.de/ika
Copyright note:
This material is not in the public domain.The author(s) claim(s) all applicable rights.However, permission to copy it is granted under the condition that proper reference is given to the author(s).
Corresponding author:
------------------------------------------------------------Jens Blauert, Professor emeritus of Acoustics
Institute of Communication AcousticsRuhr-Universitaet BochumD-44780 Bochum, Germany
Tel.: +49 234 322 2496 (direct: 3480)Fax: +49 234 321 4165e-mail: [email protected]://www.rub.de/ika
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