Ladefoged (Elements) – Chapter 4 – Wave analysis

The waveform is rarely the best representation for analysis of sound, and this is an intuitive introduction to why.

Ladefoged (Elements) – Chapter 3 – Quality

A general term for aspects of sound other than loudness and pitch. Different vowels, for example, have a different quality of sound.

Ladefoged (Elements) – Chapter 2 – Loudness and pitch

These are perceptual phenomena that relate to physical properties of sound.

Ladefoged (Elements) – Chapter 1 – Sound waves

Very brief, but a reasonable place to start if you have no idea what sound is.