Podcasting Hacks

Glossary

Audio has its own language. This short glossary provides definitions of some of the audio-specific terms found in this book:

AAC

Advanced Audio Coding, a synonym for the MP4 audio encoding standard [Hack #18] .

ADC

An analog-to-digital converter that converts analog signals into digital bits.

AIFF

A lossless audio storage format [Hack #18] .

Aliasing

When signals are under-sampled the higher frequencies are aliased, which creates distortion in the lower frequencies. To avoid aliasing, sample the signal at the Nyquist frequency.

Ambience

Background sound material [Hack #64] that augments the foreground audio.

Amplifier

Amplifiers [Hack #14] increase the input audio signal strength.

Analog

Before digital recording there was analog recording, where signals were stored on either tape or vinyl.

Attenuate

A synonym for reduce that is often used to explain the effect of a filter.

Audio Unit (AU)

The plug-in [Hack #51] standard from Apple Computer. It’s a part of Apple’s Core Audio subsystem in Mac OS X.

Automation

The feature in studio mixing boards [Hack #56] that tracks the position of each control on a channel in real time during recording and playback. In the digital world this is called gain enveloping.

Balanced

A cable is balanced when there are two signal cables and another cable for the shield. A cable is unbalanced when there are two cables and one is used for the shield as well as the signal. Always use balanced cables when you can to reduce noise [Hack #61] .

Band-pass filter