Digital Noises



Computers make noises, record noises, and change noises with a fluency and grace that has never before been seen in the world. Open source is perfectly placed to take advantage of this capability --- for those who understand how digital audio works.


This talk will be a quick layperson’s survey of digital audio signal processing. The focus will be on understanding basic digital audio principles as a tool to enable open source development and use of digital audio tools.

Specific topics to be covered include

  • What’s a sound wave? How are they produced? How does the ear hear them?
  • What’s “PCM”? How is audio digitized and undigitized?
  • What’s “the time domain”? What kinds of interesting processing can be done directly to a digital audio signal — in real time or “offline”?
  • What’s “the frequency domain”? What kinds of interesting processing can be done using filtering, FFTs, DCTs, etc?
  • How can digital audio be stored? How do lossless and lossy compression schemes work?
  • How can digital audio be synthesized? What kind of techniques are commonly used in synthesis?
  • Is it really so easy to use open source tools to process digital audio? Is it really so easy to write new ones?

I have been building digital audio hardware and software for 30 years. This talk is a chance to share some of what little I’ve learned during that time with you.

Speaking experience


  • Beach headshot 64x64

    Bart Massey

    Portland State University


    Bart Massey received a BA in Physics from Reed College in 1987, and spent two years as a software engineer at Tektronix, Inc. He received his thesis MS in CS from University of Oregon in 1992 for work on concurrent programming language implementation, and his PhD in 1999 for work in “hard” AI at the Computational Intelligence research library there.

    Since then, Bart has taught open source software engineering and artificial intelligence at Portland State University and for the Oregon Master of Software Engineering program. Bart is Technologist in Residence at the Open Technology Business Center in Beaverton, Oregon, and Secretary of the X.Org Foundation Board.