User Guide

INTRODUCTION
7
PHONE
[phone]
Call our technical support line between the hours of 9 AM and 6 PM Central
Standard Time, Monday through Friday.
FAX ON DEMAND
[phone]
Our Fax on Demand service is available 24 hours a day as an option on the
main Sonic Foundry phone line.
OVERVIEW OF DIGITAL SOUND
If you are new to digital sound editing, it will be well worth your time to
become familiar with some basic concepts. This section covers the most
important fundamentals. However, we strongly recommend that you page
through a book on digital audio and sound recording if you want to get the
most out of Sound Forge XP’s editing and digital signal processing features.
SOUND WAVES
When you hear a sound, you are sensing changes in the air pressure around
your eardrum. You can think of air pressure as the density of air molecules.
When an object vibrates or moves, it displaces air molecules causing a pressure
change. This in turn causes other air molecules to move. We don’t hear air
pressure changes caused by the weather. Instead, we hear air pressure
differences that vary rapidly over time.
These rapid vibrations are picked up by your ears and converted to electrical
signals that your brain interprets as sound. If we were to graph the air pressure
at your eardrum as a function of time while you were listening to a short
sound, it might look like the waveform below.