Apple Soundtrack Pro User Manual download pdf (Page 287)

287

Appendix

C Audio Basics

You can create professional-sounding music projects in Soundtrack Pro without any

background or training in music. This chapter describes the basic audio and music

concepts you need to know to get started.

Basic Audio Concepts

In order to understand how you can work with audio files and use the controls, effects,

and envelopes included in Soundtrack Pro, it’s helpful to know some basic terms and

concepts about audio.

Sound Waves

What we hear as sounds are vibrations traveling through the air as sound waves. Sound

waves move through the air like ripples in a pond, radiating outward from the sound’s

source in a regular pattern of compression and rarefaction.

Frequency and Amplitude

The rate at which a sound wave repeats (the time between two peaks of the wave) is

called its frequency. Frequency is expressed in cycles per second, or Hertz (Hz). We hear

a sound’s frequency as being relatively high (like a flute, a child’s voice, or a train

whistle) or low (like a bass guitar, a man’s voice, or the rumble of a train on the tracks).

The range of frequencies audible to human beings is roughly 20 Hz–20 kilohertz (kHz).

The depth or intensity of a sound is called its amplitude, and is expressed in decibels

(dB). We hear amplitude as the volume or loudness of a sound. The range of audible

loudness is roughly 0–130 dB. Higher decibel levels are painful to human hearing.

Frequency

Amplitude

Time

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Apple Soundtrack Pro User Manual Page 287