CSE3325: Sound

In the previous lecture:

In this lecture:


There are many good books on electronic sound and music... most of them have nothing to do with the WWW! This area is so vast that it is ridiculous to pretend that a single lecture can do any more than scratch the surface. I suggest you head to the library and start reading anything on the subject which takes your interest!

Roads, C. "The Computer Music Tutorial", MIT Press 1996

...is however an excellent general text on the subject of computers and music!

guitar player

This material relies heavily on examples played during the lecture. Of course you were there so you knew that!

The Attributes of Sound



frequency spectrum of pitch C4
sin wave tone
(note the fundamental)

frequency spectrum of pitch C4
square wave tone
(fundamental + overtones)


Loudness (Dynamics)

Attack - Decay

Simple model:

More completely specified envelope (ADSR):

ADSR envelope

Different sounds have different envelopes:

piano envelope organ envelope

Digital Audio

hello envelope
Fig 1: Spoken 'hello' waveform
(8 bits per sample, 22kHz sampling rate)

hello wave section

Fig 2: Close-up of spoken 'h...'

hello samples

Fig 3: Extreme close-up of 'h...'

Music, Sound or Noise?

Sound, Little Images and Big Images

Sound For Moving Pictures

Literal Sounds: emerge from a sound source to which the sound refers.

Non-literal Sounds: are not intended to convey a literal meaning, nor be identified with a source.

Source disconnected non-literal sounds do not evoke a visual image of the source.

Descriptive Non-literal Sounds

Sounds can evoke or describe:

  • Moods (like colours)
  • Places
  • Times
  • Attributes (heavy, rough, cold)
  • And more!
  • What do these sound like?

  • Infinity
  • Rough
  • Sharp
  • Soft
  • Hot

    • Icy
    • Heavy
    • Squishy
    • Solemn
    • Potato

    Recording Sounds

    Sounds for Interfaces

    Web Sound

    Down-loadable audio digital sound files are down-loaded in total by a user before playback using a helper application.

    Common digital audio file format extensions:

    <A HREF="path/mySound.mp3">soundName</A>

    Streaming audio digital sound files run in a real-time stream to client. The client plays as much of the file as possible as it is received.

    Format: RA (RealAudio)

    MIDI - Musical Instrument Digital Interface

    A computer can be set up as a software synthesizer to receive and play MIDI messages if it stores at least General MIDI instrument data. MIDI files are MUCH smaller than digital audio files because the sound waveforms are stored on the client. Only note information needs to be sent over the Internet, a considerable saving over sending the entire sound waveform!


    Free MP3 files for techno-heads who love thumping BASS

    All that's wrong with commercialization is evident here - just look at the RA player interface!

    A record company making the most of Real Audio and MP3 to publicize their material


    This lecture's key point(s):

    CSE3325 courseware | CSE3325 lecture notes

    ©Copyright Alan Dorin 2005