Waves Audio Doppler User Guide

Table of Contents

Chapter 1 ............................................... Quickstart .... 2

Chapter 2 .............................. General Introduction .... 4

Chapter 3 ........................................Example of Use .... 5

Chapter 4 ............................ Controls and Interface .... 8

Chapter 5 ................................. Preset Descriptions . . 12

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Chapter 1 - Quickstart

Doppler is the effect heard when a sound source, such as a car or train, passes by, and the pitch changes. Pitch
sounds higher as the sound approaches, and sounds lower as it goes away.

Waves Doppler processor is very easy to operate and has a small set of controls. It is based “on reality” in that
some controls behave according the laws of physics (air damping, gain changing with distance). However you can
set the values of Doppler to work well outside those laws; it is said there is “reality”, and there is “Hollywood”,
when it comes to effects and the appropriate perception of them. Sometimes what an audience would expect is
not based on the laws of physics at all!

The main controls of the Track are:

• Start position

• End position

• Curve of the line (middle handle on Track)

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Doppler GUIDoppler GUI

Doppler GUI

Doppler GUIDoppler GUI

The interface shows a rectangular space in front of “you, the listener”. Imagine that you are standing at the
bottom center of the space (indicated by the red dot) and the object will pass in front of you.

Basic Operation

• Select the audio segment you wish to preview, noting the length in seconds.

• Select the Doppler plug-in from your plug-in menu.

• Set the Track Time (in seconds) to the length of your audio segment.

• Preview the sound to start the Doppler effect.

• Adjust the curve of the Track by dragging the center handle.

QuickTips

The Center Time control will adjust when the peak of the Doppler effect occurs. By default it is always one-half
the value of the Track Time, but you may need for the effect to peak at a different time in the Track. Note that the
Curve Handle does not reflect this Center Time, but the speed of the Travel Cursor does reflect the relationship of
the Center Time.

The controls on the right side of the interface allow you to adjust the “reality” parameters, such as gain, air
damping, and so forth. You may reduce them to zero or increase them to exaggerated levels. For all of these
controls, setting the value to 100% represents a realistic behavior in moderate air temperature at sea level. Values
of 0% will turn that control off; each has a range up to 200% for exaggerated effects.

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Chapter 2 - General introduction

A little history

The Doppler effect was named for an Austrian physicist, Christian Doppler (1803-1853), who theorized that
sound waves from a moving source would be closer together as the sound came closer, and further apart as the
sound went further away. The frequency that would be heard would change. Closer-spaced waves would have a
higher pitch, and waves further apart would have a lower pitch. This is due to the fact that the speed of sound is
relatively constant (although a relative one, depending on altitude, temperature, and humidity).

Mr. Doppler proved his theory in 1842 by having trumpet players standing on a train pass by at varying speeds.
He also had a musician stand with him who could take careful note of the changes in pitch of the trumpets as the
train passed by. This proved his theory very well, and he also theorized that this would apply to light, but he
couldn’t create a proof for this.

Later, a scientist named Fizeau generalized Doppler’s theorem and did indeed find that the Doppler Effect was
applicable to light and to other propagations of waves through mediums. For example, this is how the police can
track the speed of a moving car, and how it has been theorized that the universe is expanding (by observing the
“red-shift”, or lowered frequencies of stars moving away from our perspective). OK, that’s probably enough
history. There will not be a test.

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