Virtual Instrument Design and Animation

Cynthia BruynsRobert TaylorCarlo Séquin

University of California at Berkeley

AimAim

To provide an environment for evaluating the

sound qualities of modeled simple idiophones

Images courtesy of Steve Reinmuth

AimAim

To recreate the object’s sound in an interactive environment

To be able to use these sounds to extend synthesis for computer music

Modeled Objects Mode Activation

Previous Sound Generation ResearchPrevious Sound Generation Research

StochasticSerra, X. et al. 1990

Cook, P. 2001

Texturesvan den Doel, K. et al.

2001

Di Fillipo, D. et al. 2000

AnalyticSmith, J. 1992

Cook, P. 1995

ModalMorrison, J. et al. 1993

O’Brien, J. et al. 2001

Methods for sound synthesis for graphics

Geometric ModelsGeometric Models

Simple or complex shapes

Multiple resolutions are generated

Can use thin or solid models

Physical ModelPhysical Model

Modal FormulationModal Formulation

Mode Shapes (exaggerated)Mode Shapes (exaggerated)

Modal ActivationModal Activation

Load model geometry into viewer program. Choose materials parameters. Select several strike locations on the model

– and map to keys of a midi keyboard.

PLAY ! – Key velocity determines intensity of strike.

Interactive Sound GenerationInteractive Sound Generation

Software created as an Audio Unit plug-in

Can be used in AU host applications

This allows for sound generation in a composing environment

Strike Location

Sound ValidationSound Validation

Synthesized sounds were compared with actual object sound generation Square plate

Aluminum

Steel

Rectangular plate

Aluminum

Odd shaped plates

Aluminum Model Real

Measurement SetupMeasurement Setup

Sound dampened room

Selection after transients

FFT analysis of identical time intervals

Time (seconds)

Fre

quen

cy (

Hz)

Am

plitu

de (

dB)

AnalysisWindow

?

Square (Aluminum)Square (Aluminum)

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l (dB

/Hz)

60

40

20

100 200 500 1000 2000

Materials

Model

Square (Steel)Square (Steel)

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l (dB

/Hz)

60

40

20

100 200 500 1000 2000

Materials

Model

Rectangle (Aluminum)Rectangle (Aluminum)

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l (dB

/Hz)

60

40

20

100 200 500 1000 2000

Materials

Model

?

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l (dB

/Hz)

60

40

20

100 200 500 1000 2000

Materials

Model

Odd Shaped Plates - “S”Odd Shaped Plates - “S”

Odd Shaped Plates - “G”Odd Shaped Plates - “G”

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l (dB

/Hz)

60

40

20

100 200 500 1000 2000

Materials

Model

Demo PlateDemo Plate

Demo Odd ShapeDemo Odd Shape

Summary and DiscussionSummary and Discussion

System for generating “ringing” sounds

More “natural” => more interesting

Real-time generation of strike-sounds.

System may become predictive enough to allow interactive design of new “bells”

Real-time shape modifications an re-analysis ?

Extensions:

Non-linear phenomena during initial strike

Include coupling with environment (air).

AcknowledgementsAcknowledgements

Apple Computer

Ruzena Basjcy

David Bindel

Jon Drukman

Justin Maxwell

James McCartney

Kim Silverman

Bill Stewart