William Allaudin Mathieu is an author and musician. He is a pianist who has studied Indian vocal music with Pandit Pran Nath.

His books include:

• The Listening Book (1991) Shambhala. ISBN 0877736103.
• Harmonic Experience: Tonal Harmony from Its Natural Origins to Its Modern Expression (1997) Inner Traditions Intl Ltd. ISBN 0892815604.

Harmonic Experience is a autodidactic ear-training and sight-singing book that uses singing sargam syllables over a drone in a just intonation system based on perfect fifths and major thirds.