John Keston Classes

Week 1

Session 1: Today we’ll discuss a few principals of sound itself. Sound is made up of high and low pressure waves that travel through matter. We can perceive sound traveling through air at frequencies ranging from roughly 20hz to 20khz, and are able to record it using microphones and analog or digital recording media.

What’s the difference between analog and digital recording? Analog recording translates the sound waves into an analog electronic signal which is then stored on magnetically sensitive tape. Digital recording samples the sound at intervals in time. The rate of these intervals is called the sampling rate and is indicated in Hertz or KiloHertz. The faster the rate, the higher the recording quality. The sampling bit depth indicates the resolution of the sample, or how the amplitude of the sampled sound wave is divided. CDs use 16 bit resolution and a sampling rate of 44.1Khz (KiloHertz). The information is then stored on some type of digital media such as a hard drive in a computer, a CD, or a DAT (Digital Audio Tape) cassette.

DSP or Digital Signal Processing is the manipulation digital audio without converting it to analog. There are many different types of DSP. Each type is essentially a different algorithm with a set of user adjustable parameters used to manipulate digital audio. Some examples of DSP include level or volume adjustments, equalization or filtering, panning, looping, delay or echo, reverberation, time compression or expansion, and pitch shifting.

Please bring a set of closed ear headphones and a CD which contains some audio to sample from for our in class exercise week 1, session 2. The assignment will involve basic ProTools techniques including sampling and signal processing.

Required Reading:
Recording Technology History
Digital Audio Basics
Reading:
Real World Digital Audio, Chapter 1 - Understanding Digital Sound

Files:
Sine wave files

Session 2: Today we will be sampling from a cd of your choice and then using DSP to loop and manipulate a small segment of a piece of digital audio from your CD. Use iTunes convert a track from your CD into a .wav file, then import the audio into ProTools. I will be demonstrating this process in the lab.

Once you’ve converted your track, use ProTools to select a reagion or loop of audio that you want to work with. Apply pitch shifting and at least two more kinds of processing in order to come up with a new and completely different sounding loop. When you’re happy with the results bounce the audio to a new file and copy the loop to the drop off drive in the “John Keston” folder under “ca2431″ in a directory named . We will listen to the loops in class on so make sure you have finished before Session 1, Week 2.