optimizing a 3d audio teleconference application · contents motivation and concept overview...

Interactive Communication Systems (ICS)Wilhelm-Schickard Institute - Dr. Christian Hoene

© 2010 Universität Tübingen, WSI-ICS

Mansoor Hyder, Michael Haun, Dr. Christian Hoene

ETSI-QoS QoE User Experience Workshop, Sophia Antipolis, September 21-22, 2010

Optimizing a 3D Audio Teleconference Application

Contents

Motivation and Concept

Overview

Methodology

Test Design

Results

Summary

Future Work

2Optimizing a 3D Audio Teleconference Application

Drawbacks of Classic Telcos

Teleconferencing offers advantages Allows collaborative communication

Saves traveling time and costs

Overcoming of geographical separations

Teleconferencing displays shortcomings No significant improvement of audio quality over time

Competition between interactivity and number of users

Competition between understandability and number of users

User expectations not satisfied


Spatial Audio for Telcos

Incorporating 3D spatial audio provides natural communication feeling...

… but not all researchers reported an increase in quality …

… thus further measures have to be taken to optimize spatial audio teleconferencing, e.g. Proper selection of virtual environment

User opinions4Optimizing a 3D Audio Teleconference Application

Optimizing Spatial Audio Teleconferencing

Careful selection of virtual acoustic parameters Room size

Participants sitting arrangement

Conference table size

Number of simultaneous talkers

Simultaneous talkers voice characteristics

User opinions on Easiness to locate talker of choice

Spatial Audio Quality

Overall Audio Quality and comparison with natural communication


Our 3D Telephone System

3D Telephony Open source

Based on Uni-Verse [1]

Optimized to be used with Ekiga Softphone

Customizable virtual environment

Previous work Implementation of prototype

User studies

Opinions on Audio Quality

Studying various placement of participants

[1] Raine Kajastila, Samuel Siltanen, Peter Lunden, Tapio Lokki, and Lauri Savioja. A Distributed real-time virtual acousticrendering system for dynamic geometries. In 122nd Convention of Audio Engineering Society (AES), Vienna, Austria, May 2007.


Methodology

Conduction of listening-only tests on locatability and quality (MOS)

Using cubic virtual rooms with round conference table placed in center

Analyze the influence of Voice characteristics

Number of concurrent talkers

Table size

Sound Source position density

Room size

Comparison of each setup with reference setup


Listenings-Only Tests and Audio Samples

Participants 31 subjects, 13 Female, 18 Male

Average Age 27 years

Normal listening ability

Good to professional level computer proficiency

8 subjects had previous listening only test exposure

Audio samples Male/Female anechoic voice samples

ITU-T Rec P.50 Appendix 1 Library

Prerecorded from and processed with Uni-Verse


Test Design - Setups

Five setups Two tests per setup

One reference test

11 test, 2201 audio samples in total

Series of three tests for each parameter Reference, Tested-Parameter-1, Tested-Parameter-2


Test Parameters

Talkers' voice characteristics m/m, f/f or f/m talker combination

Number of concurrent talkers 2, 3 or 4 simultaneous talkers

Table size Radii of 2, 3 or 4 m

Number of sound source locations 4, 6 or 8 possible talker locations

Room size Room sizes of 20x20x20m, 15x15x15m or 10x10x10m

(LxWxH)10Optimizing a 3D Audio Teleconference Application

Overview


An schematic overview of the virtual test environment and all measured parameters

Voice Characteristics

Opposite gender talkers easier to localize

Female/Female hardest to localize


Number of Talkers

Localization performance increases with number of talkers

Subjective localizing easiness decreases


Table Size

Localization performance increases with table size

Subjective localizing easiness stable


Talker Location Density

Localization performance decreases with increase in talker location density

Decrease in MOS-LQSW- easiness values


Room Size

Localization performance decreases with increasing room size

Better MOS values with medium size room


Audio Quality


MOS-LQSW for spatial quality and overall audio quality achieved nearer values throughout the test

Better MOS-LQSW values for spatial quality and overall audio quality were observed for mix gender talker test and medium sized room

Summary

Each parameter has substantial influence on talker locatability

Mixed gender talkers were found easier to localize

An increase in table size brought increase in localization performance with no significant difference found in MOS-LSQW-localization easiness values for all table sizes

An increase in possible talker locations resulted a significant decrease in localization and MOS-LSQW localization easiness values

Decrease in room size resulted an increase in localization performance


Future Work

Adding MEMS based head-tracking to “3DTel”

Mapping user position and orientation in a room

Study possibilities to use WiiMote as a head-tracking device


optimizing a 3d audio teleconference application · contents motivation and concept overview...

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