Among the sounds of languages, consonants and vowels need no explanation to the lay person, but tones are another matter entirely. Tell someone you are writing a book about ‘Tone’, and they look blank, and yet by some estimates as much as 60–70 per cent of the world's languages are tonal. Begin to explain that you are interested in languages that use the pitch of the voice to convey meaning, and more often than not you will be interrupted with a remark such as ‘Oh, that must be really interesting: those emotions and nuances and subtleties are so important when we're speaking!’ Politely explain that actually you are interested in languages that use pitch to distinguish one word from another, not just to convey subtleties, and most people will assume that such languages are rare, and probably spoken only by isolated communities in less developed countries – until you point out that Mandarin Chinese (885,000,000 speakers), Yoruba (20,000,000) and Swedish (9,000,000) are all tonal.

Perhaps because of these misapprehensions (particularly prevalent in Western cultures), even among linguists tone is sometimes seen as a specialized topic that the general linguist can largely ignore. Undergraduate courses often pay it only cursory attention, and even graduate courses may devote no more than a class or two to the topic. The goal of this book is to fill that gap. It assumes a basic knowledge of phonological theory, but no prior acquaintance with the phonology of tone.