tone, in linguistics, a variation in the pitch of the voice while speaking. The word tone is usually applied to those languages (called tone languages) in which pitch serves to help distinguish words and grammatical categories—i.e., in which pitch characteristics are used to differentiate one word from another word that is otherwise identical in its sequence of consonants and vowels. For example, man in Mandarin Chinese may mean either “deceive” or “slow,” depending on its pitch.
In tone languages, pitch is a property of words, but what is important is not absolute pitch but relative pitch. Tone languages usually make use of a limited number of pitch contrasts. These contrasts are called the tones of the language. The domain of the tones is usually the syllable.
There are two main types of tone languages: register-tone, or level-tone, languages and contour-tone languages. Register-tone languages use tones that are level; i.e., they have relatively steady-state pitches, which differ with regard to being relatively higher or lower. This is characteristic of many tone languages in West Africa. In contour-tone languages at least some of the tones must be described in terms of pitch movements, such as rises and falls or more complex movements such as rise–falls. This is characteristic of many tone languages of Southeast Asia.