Alice Workshop

Working with Sound

Sound

Working with sound is appealing to students

Demo: Penguin Sound

Opportunity

Using sound offers an opportunity to discuss fair use and copyright guidelines.

For educational purposes, fair use and copyright guidelines rule of thumb is 30 seconds*.

http://www.utsystem.edu/ogc/INTELLECTUALPROPERTY/ccmcguid.htm

* Or 10%, whichever is less

Questions

Questions students ask:Can more than 1 clip (from different sound files) be used? Yes

Can a 30 second clip be played again and again? Yes

How to get a 30 second sound clip?

Sound editor

Alice is not, nor has, a sound editor.

Obtain sound editor softwareExample: Audacity

Freeware from audacity.sourceforge.net/download/

Soundcards

Audacity works with OSCapturing sounds to a fileEditing filesMixing different tracks

OS of the computer uses a soundcard toConvert analog sound (from a CD) to digital format when recording, andConvert digital sound file to analog sound, when playing audio

Digital Sound

Digital wave form

Each dot in the figure above represents one audio sample.

Sample Rate

The rate at which the samples are captured, measured in Hertz (Hz), or samples per second.

For Alice clips we will use a sample rate of 22.5 KHz

Higher sampling rates allow a digital recording of higher quality.

Sample Size

Essentially this is the number of digits in the digital representation of each sample.

Think of the sample rate as the horizontal precision of the digital waveform, and the sample size as the vertical precision.

Higher sample sizes allow for more dynamic range - louder louds and softer softs

File Formats

Uncompressed (Pulse Code Modulation)Each number in the file corresponds to one sample

Audacity supports WAV, AIFF, and others

CompressedLogarithmic encodings

Audacity supports MP3 and Ogg Vorbis

Not WMA and MPEG4 (AAU)

Alice supports WAV and MP3

Launch Audacity

Original Song

Clip from Song

Penguin Sound

Has a 3+ minute sound track

Modify to use a 30 second clip repeatedly

Skate Routine

SkateRoutineGrab a 30 second clip from a song

Import it into an existing world

Add it to the skating routine