Hybrid Percussion: Extending Physical Instruments Using Sampled Acoustics Roberto Mario Aimi

138 Pages·2006·13.01 MB·English

Hybrid Percussion: Extending Physical Instruments Using
Sampled Acoustics
by
Roberto Mario Aimi
S.B., Biology, Massachusetts Institute of Technology (1997)
S.M., Media Arts and Sciences, Massachusetts Institute of Technology (2002)
Submitted to the Program in Media Arts and Sciences,
School of Architecture and Planning
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy in Media Arts and Sciences
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
February 2007
(cid:13)c Massachusetts Institute of Technology 2007. All rights reserved.
Author............................................................................
Program in Media Arts and Sciences
October 31, 2006
Certified by........................................................................
Tod Machover
Professor of Music and Media
Thesis Supervisor
Accepted by.......................................................................
Andrew Lippman
Chairman, Department Committee on Graduate Students
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Hybrid Percussion: Extending Physical Instruments Using Sampled
Acoustics
by
Roberto Mario Aimi
Submitted to the Program in Media Arts and Sciences,
School of Architecture and Planning
on October 31, 2006, in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy in Media Arts and Sciences
Abstract
This thesis presents a system architecture for creating hybrid digital-acoustic percussion
instruments by combining extensions of existing signal processing techniques with specially-
designed semi-acoustic physical controllers. This work aims to provide greater realism to
digital percussion, gaining much of the richness and understandability of acoustic instru-
ments while preserving the flexibility of digital systems. For this thesis, I have collaborated
with percussionists to develop a range of instruments, to refine and extend the algorithmic
and physical designs, and to determine successful models of interaction.
Conventional percussion controllers measure and discretize the intensity of strikes into
discrete trigger messages, but they also ignore the timbre of the hits and fail to track more
ambiguous input. In this work, the continuous acoustic output of a struck physical object
is processed to add the resonance of a sampled instrument. This is achieved by employing
existing low-latency convolution algorithms which have been extended to give the player
control over features such as damping, spectral flattening, nonlinear effects, and pitch.
One of the advantages of this approach is that light taps, scrapes, rubs, or stirring with
brushesalltakeonahybridtimbreoftherealandsampledsoundthatissurprisinglyrealistic
and controllable. Since part of its behavior is inherently acoustic, a player’s intuition about
interacting with physical objects can be applied to controlling it. The ability to transform
the apparent acoustic properties of objects also suggests applications to HCI and product
design contexts.
Thesis Supervisor: Tod Machover
Title: Professor of Music and Media
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Hybrid Percussion: Extending Physical Instruments Using Sampled
Acoustics
by
Roberto Mario Aimi
Thesis Readers:
Thesis Reader .....................................................................
Joseph A. Paradiso
Associate Professor
MIT Media Laboratory
Thesis Reader .....................................................................
Hiroshi Ishii
Associate Professor of Media Arts and Sciences
MIT Media Laboratory
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Acknowledgments
Thanks to:
my advisor, Tod Machover; my readers, Joe Paradiso and Hiroshi Ishii
percussionists: Rakalam Bob Moses, Jamey Haddad, Curt Newton, Dave Flaherty
Bill Gardner, Gili Weinberg, my friends, family, the Opera of the Future group everyone
who had input on the document, the instruments, and the talk.
the Media Lab staff, students, faculty for their help, feedback, and daily inspiration.
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Contents
1 Introduction 17
1.1 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.2 How this approach differs from existing trigger-based electronic percussion
systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.3 Musical vision: realistic, physically grounded timbral behavior for digital
percussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4 Structure of this document . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2 Musical mappings, spectral continuity, and percussion. 23
2.1 The mapping problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.1.1 Simpler isn’t always better. . . . . . . . . . . . . . . . . . . . . . . . 25
2.1.2 An instrument as an extension of the body . . . . . . . . . . . . . . 25
2.2 How is percussion special? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.3 Spectral continuity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3 Background 31
3.1 Historical precedents for electronic/acoustic instruments . . . . . . . . . . . 31
3.1.1 The Stroh violin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.1.2 The National Resonator Guitar . . . . . . . . . . . . . . . . . . . . . 38
3.1.3 The Rickenbacker electric guitar . . . . . . . . . . . . . . . . . . . . 41
3.1.4 Ondes Martenot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.2 Electronic percussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.2.1 A brief history of electronic percussion . . . . . . . . . . . . . . . . . 46
3.2.2 Contemporary commercial approaches . . . . . . . . . . . . . . . . . 47
3.3 Convolution in computer music . . . . . . . . . . . . . . . . . . . . . . . . . 53
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3.3.1 A graphical example of convolution . . . . . . . . . . . . . . . . . . . 56
3.4 Other approaches: physical modeling and modal synthesis . . . . . . . . . . 58
4 System design and software implementation 61
4.1 How the system works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.2 Initial proof of concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.3 Further implementations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.3.1 Pd patch architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.4 Nonlinear responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5 Other expressive controls, extensions to realtime convolution 67
5.1 Damping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.1.1 Simple damping model . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.1.2 Frequency-dependent damping . . . . . . . . . . . . . . . . . . . . . 78
5.1.3 Pitch shifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.1.4 Cross fading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.1.5 Inverse filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.1.6 Crashing a ride cymbal: pseudo- nonlinear processing . . . . . . . . 85
5.2 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6 Physical controllers 89
6.1 Cymbal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.1.1 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.1.2 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.1.3 Brushes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.1.4 Wireless brush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.1.5 Wired brush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.2 Pad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
6.3 Frame drum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.3.1 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.3.2 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.4 Bass drum with speaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.4.1 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
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