Sound Displays

1
Sound Displays

• Sie-Kyung Jang
• 2003.11.22
• CS788 HCI VR
• KAIST

2
Overview

• Introduction
• The Human Auditory System
• Azimuth Cues
• Elevation Cues
• Range Cues
• Head-Related Transfer Function
• The Convolvotron
• Speaker-Based Three-Dimensional Sound

3
Introduction

• Sound displays?
• An output device from virtual to real

4
The Human Auditory System

• The Vertical-Polar Coordinate System

• Azimuth
• Elevation
• Range
• ( ? , f , r )

?

• Angle ? between nose and a plane containing the
  source and the
• vertical axis z.
• Range -180 180

5
The Human Auditory System

• The Vertical-Polar Coordinate System

• Azimuth
• Elevation
• Range
• ( ? , f , r )

f

• Angle f made with the horizontal plane by a line
  passing through the source and the center of the
  head.
• Range -90 90

6
The Human Auditory System

• The Vertical-Polar Coordinate System

• Azimuth
• Elevation
• Range
• ( ? , f , r )

r

• Distance between sound source and head center
• Range Head Radius lt r (only )

7
Azimuth Cues
(a radius, c velocity)
8
Elevation Cues

• Pinna reflections and resonances
• Torso and shoulder reflections

9
Range Cues

• Loudness
• Direct vs reverberant ratio

10
Head-Related Transfer Function

• Captures the location-dependent spectral changes
  when a sound wave propagates from a sound source
  to the listener's ear drum
• Spectral changes are due to diffraction of the
  sound wave by the torso, head, and outer ears or
  pinnae

11
The Convolvotron

• Developed by Crystal River Engineering, 1988.
• Real-time digital signal processor

12
The Convolvotron

• Process
• 3D tracker send position data to host com.
• Calculates the new position of the simulated
  sound
• Apply the Head-Related Transfer Function
• Play back the sound

13
Speaker-Based 3D Sound

• Stereo Format
• Quad Format
• 5.1 Surround Format
• Dolby Digital

14
Speaker-Based 3D Sound

• MS DirectSound 3D
• 3-D Sound Accelerators For DirectX-Powered
  Interactive Content
• H/W
• Creative EAX(Environment Audio Extension)
• Aureal A3D
• Supprot DirectSound 3D