Kalpit V. Desaikvdesai@email.unc.edu

SoundMaker

Physics-Based Synthesis of Car Sounds

Overview

• Synopsis

• Motivation

• Overall Approach

• Detailed Model

• Demo

Synopsis

• Synthesize sounds of a car• Target application: Street-Crossing

Simulatorother applications: Setting noise standards, Games etc.

• Goal: to develop a parametric model based entirely on principles of physics

• Use of signal processing concepts• Why not use recorded sounds?

Motivation• Recorded sounds

– Noise or extraneous inputs in recordings– Inefficient for real-time control– Limited applicability

• Parametric model– Versatile:

change in value of parameter = a new car

– Efficient for use in real-time

Overall Approach

Engine+muffler

Weight

C/SArea

Velocity

Acceleration(throttle)

Wind

Tyres

RPM

Doppler+

++

Stereo Output

Detailed Model: Engine 4 strokes

Detailed Model: Engine (Cont)

Engine

One Cycle

Remove Frequencies

>20KMuffler

Output

SoundsRPM

Model: Wind & Tyres• Wind Friction

– Band Limited White Noise (negligible at very low frequencies)

– Amplitude proportional to square of velocity

– Amplitude proportional to cross-section of vehicle

• Tyres– Band limited pink noise (HF prop. to

velocity)– Amplitude proportional to weight

Doppler Effect

Demo

(urr…sort of )

Future Plans (before GrandET demo)

• Solve the puzzle of muffler model• Add Doppler effect• Replace Matlab script with interactive

GUI

Questions?

Thank You!