3D Sound Simulation over Headphones

3D Sound Simulation over Headphones

Lorenzo Picinali (De Montfort University, UK)
DOI: 10.4018/978-1-60566-352-4.ch007
OnDemand PDF Download:
$37.50

Abstract

What is the real potential of computer science when applied to music? It is possible to synthesize a “real” guitar using physical modelling software, yet it is also possible virtually to create a guitar with 40 strings, each 100 metres long. The potential can thus be seen both in the simulation of that which in nature already exists, and in the creation of that which in nature cannot exist. After a brief introduction to spatial hearing and the binaural spatialization technique, passing from principles of psychoacoustics to digital signal processing, the reader will be included on a voyage through multi-dimensional auditory worlds, first simulating what in nature already exists, starting from zero and arriving at three “soundscape dimensions”, then trying to advance the idea of a fourth “auditory dimension”, creating synthetically a four-dimensional soundscape.
Chapter Preview
Top

Introduction

What is the real potential of computer science when applied to music?

Using physical modelling synthesis techniques it is possible to simulate as accurately as possible an acoustic guitar: of course, this is useful in terms of the opportunities made available to musicians to use an instrument they cannot in reality play, and in terms of acoustical studies of the instrument itself. But: Is that it? Once created, a guitar mathematical model can be altered as far as the imagination can extend: an acoustic guitar made of gold, with 40 strings, each of 100 metres in length, could virtually be created and played with a one-square-metre plectrum! Therefore, the potential can be seen both in the simulation of that which in nature already exists, and in the creation of that which in nature cannot exist.

Another kind of example will be discussed later in the chapter: instead of toying with the simulation of musical instruments, we shall try to create virtual acoustical environments through the simulation of three-dimensional (henceforth: 3D) soundscapes. The binaural spatialization technique will be used in order to achieve this goal; multi-dimensional soundscapes will be simulated not by placing real sound sources, such as loudspeakers, within the three dimensions, but by simulating the behaviour of our outer ear in terms of directional modifications brought to the sound input into the hearing system.

The mechanisms of spatial hearing will be investigated and analyzed, and three localization cues will be characterized and simulated. These are the Interaural Level Differences (ILDs), the Interaural Time Differences (ITDs), and the Direction-Dependent Filtering (DDF). Within the simulation of a real environment, these parameters would all be coherent with the position of the sound source: for example, for a sound source placed at 60° of azimuth, the sound would reach first the right ear and then the left (ITDs). Furthermore, it would be more intense at the right ear (ILDs) than at the left, and the sound would be filtered depending on the particular resonances of our outer hearing systems for that specific sound source location.

It must, however, be asked what could happen if the three localization cues were incoherent with the real position of the sound source. Of course, this is impossible in nature, and equally so in a standard soundscape simulation, when loudspeakers are placed in a 3D space. Still, achieving such incoherence is not impossible in a system based on headphones, where the signals sent to the hearing system are much more controllable, thus the whole reproduction system results may be much more flexible.

In this case, the binaural spatialization technique is useful not only to simulate a real 3D soundscape, but also to create new soundscapes, i.e., environments that are impossible to find in the real world. This seems to be one of the amazing new options offered by computer science: while it could indeed be considered inessential to simulate a feature that already exists in nature, it is particularly interesting to create a feature that as yet has no existence in the real world.

To appreciate this new ‘digital feature’ fully, it may help to think about a voyage into multiple dimensions; the results may appear similar to Abbott’s graphic achievements (seeAbbott, 1999) when he wrote Flatland (frequent reference will be made to this book later in the chapter). A monophonic diotic signal (the same at both ears) could be perceived as a point sound source located in the middle of the head: zero dimensions, or the point. By introducing intensity and content differences between the two channels (ILDs) and creating a dichotic signal (different for each of the ears), it is possible to obtain a standard headphone stereo signal, with multiple sound sources located along a line between the ears (always inside the head): one dimension, or the line. Through introducing time differences between the two channels (ITDs), it is possible to obtain the sensation of the sound coming from out of the head, and with multiple sound sources located in a plane: two dimensions, or the square. Then, upon introducing a simulation of the DDF, with different frequency filtering for each virtual sound source, the perception reaches the third dimension, the cube. The auditory passage between these steps could be visualized as the graphic perception of a point that becomes a line, then a square and at the end a cube. What, then, about the fourth dimension?

Key Terms in this Chapter

Soundscape: An acoustical environment or an environment created by sound.

Impulse Response (IR): The recording of an impulse signal that has passed through and been processed by a given system. It unequivocally describes the behaviour of that specific system to all of the possible input signals.

Sound Localization: The judgement of the specific location of a sound source.

Head Related Transfer Function (HRTF): The transfer function of the external hearing system and of all the other elements that contribute to the directional modifications of the signals input to the hearing system (torso and shoulders).

Fourth Dimension: There is no unequivocal definition of the fourth dimension. For most, scientists included, time is considered to be the fourth dimension, yet in this chapter an attempt at a different definition is executed.

Three-Dimensional Soundscape: The ensemble of the sounds heard in a particular location where the sound sources are placed in the three dimensions (x, y and z, or length, height and width).

Convolution: A fundamental mathematical function that involves sampling multiplications in multi-dimensional matrices. In the case of digital signal processing, convolution can be seen as a particular kind of multiplication between two vectors.

Binaural: Relating or involving a sound stimulus presented to both ears. In a more general sense, the expression ‘binaural spatialization’ refers to the technique for the simulation of 3D soundfields over standard stereo headphones. When the binaural signals, previously modified by the mean of special processes called ‘cross-talk’ cancellation filters, are played through loudspeakers, the term used to define this situation is transaural.

Sound Spatialization: An ensemble of sound processing techniques oriented towards the simulation of multi-dimensional soundscapes.

Localization Cues: Specific attributes of the sound event that are used by the hearing system in order to establish the position of a sound source in a 3D soundscape.

Complete Chapter List

Search this Book:
Reset
Editorial Advisory Board
Table of Contents
Foreword
Gabriele Meiselwitz
Preface
James Braman, Giovanni Vincenti, Goran Trajkovski
Acknowledgment
James Braman, Giovanni Vincenti, Goran Trajkovski
Chapter 1
Adérito Fernandes Marcos, Pedro Branco, João Álvaro Carvalho
Art objects might be described as symbolic objects that aim at stimulating emotions. They reach us through our senses (visual, auditory, tactile, or... Sample PDF
The Computer Medium in Digital Art's Creative Process
$37.50
Chapter 2
Salah Uddin Ahmed, Letizia Jaccheri, Guttorm Sindre, Anna Trifonova
The interaction between art and technology, especially computing technology, is an increasing trend in the recent years. The context of this... Sample PDF
Conceptual Framework for the Intersection of Software and Art
$37.50
Chapter 3
Joseph William Pruitt
The purpose of this chapter is to define the roles of engineering and design within the product development cycle looking at both the scientific and... Sample PDF
The Design of Engineering
$37.50
Chapter 4
Jim Bizzocchi, Belgacem Ben Youssef
The chapter describes the synergistic integration of distinct research and creation agendas, each firmly grounded in its own set of practices and... Sample PDF
Ambient Video, Slow-Motion, and Convergent Domains of Practice
$37.50
Chapter 5
Ethan Ham
Randomness is a slippery term that conveys different meanings in different disciplines. In mathematics, an individual number is random when there is... Sample PDF
Randomness, Chance, & Art
$37.50
Chapter 6
Holography: Re-Defined  (pages 103-112)
Martin Richardson, Paul Scattergood
When writing this chapter it became apparent that we were not only exponents of digital holography, but also the critics. This is a problem when it... Sample PDF
Holography: Re-Defined
$37.50
Chapter 7
Lorenzo Picinali
What is the real potential of computer science when applied to music? It is possible to synthesize a “real” guitar using physical modelling... Sample PDF
3D Sound Simulation over Headphones
$37.50
Chapter 8
Raphael DiLuzio
This is a guide for working with a visual art form using a digital time-based medium. This chapter will provide an overview of the necessary... Sample PDF
Broken Cinema: The Eye and Hand in a Time-Based Art
$37.50
Chapter 9
Ambivalent Interplay  (pages 146-161)
Heejoo Kim
The human vision, the most ubiquitous receptor of the human senses, has been the prevailing sensory organ for a noticeable manifestation of visual... Sample PDF
Ambivalent Interplay
$37.50
Chapter 10
Yueh Hsiu Giffen Cheng
The development of net art originates from the rising of net media generally. During the past two decades, Net art has overthrown the standards of... Sample PDF
The Aesthetics of Net dot Art
$37.50
Chapter 11
Nicola Quinn, Annette Aboulafia
People have used tools for artistic expression for millennia. Relatively recent is the use of digital technology to afford the creation of art.... Sample PDF
A Graphics Tablet as a Fine Art Tool
$37.50
Chapter 12
Greg J. Smith
This text seeks to contextualize the history of and discourse surrounding information visualization. It positions visualization in relation to... Sample PDF
Information Visualization and Interface Culture
$37.50
Chapter 13
Benjamin David Robert Bogart
“Memory Association Machine” (also known as “Self-Other Organizing Structure #1”) is the first prototype in a series of site-specific responsive... Sample PDF
Memory Association Machine
$37.50
Chapter 14
Stefano De Luca, Eugenia Benelli, Francesco Altarocca, Dario Dussoni
Designing good and sound architectural projects is a hard job. Generally these kinds of projects involve many stakeholders, everyone with his/her... Sample PDF
EVO-PARK: Designing Better Architecture Projects Using Participated and Interactive Genetic Algorithms
$37.50
Chapter 15
Sergiy Rakov, Viktor Gorokh, Kirill Osenkov
The chapter discusses the possibilities modern IT opens for Mathematics and its applications to real life, in particular to Art – by an example of... Sample PDF
Mathematics, Computer Mathematical Systems, Creativity, Art
$37.50
Chapter 16
Jim Barta, Ron Eglash
Students who may typically view mathematics as a sterile and disjointed subject are learning new skills and concepts using a suite of virtual design... Sample PDF
Teaching Artful Expressions of Mathematical Beauty: Virtually Creating Native American Beadwork and Rug Weaving
$37.50
Chapter 17
Mia Kalish
One visualization in Diné philosophy is four small dots arranged in a circular sequence at 90°, 0°, 270°, and 180°. Each position is associated with... Sample PDF
Visual Analytics and Conceptual Blending Theory
$37.50
Chapter 18
Lindsay Grace
Enculturation is the act of passing cultural ideologies from one person to the other. It is what breeds innovation instead of new creation. It is... Sample PDF
The Challenge of Enculturation on Art
$37.50
Chapter 19
Lindsay Grace
Software is philosophical. Software is designed by people who have been influenced by a specific understanding of the way objects, people and... Sample PDF
The Philosophies of Software
$37.50
Chapter 20
Technological Social-ism  (pages 343-374)
Judson Wright
Culture is a byproduct of our brains. Moreover, we’ll look at ways culture also employs ritual (from shamanistic practices to grocery shopping) to... Sample PDF
Technological Social-ism
$37.50
Chapter 21
Stephen A. Schrum
As creative people inhabit virtual worlds, they bring their ideas for art and performance with them into these brave new worlds. While at first... Sample PDF
Theatre in Second Life® Holds the VR Mirror up to Nature
$37.50
Chapter 22
Machinima in Second Life  (pages 396-416)
Stephany Filimon
This chapter provides a brief history of machinima, films created by computer users within virtual worlds, and focuses on machinima produced within... Sample PDF
Machinima in Second Life
$37.50
Chapter 23
Andrew Jinman
Massively multiplayer online role-playing games (MMORPGs) are becoming an increasingly popular recreational activity for social engagement.... Sample PDF
Player Motivation and Understanding Game Dynamics
$37.50
About the Contributors