The use of pitch level or pitch configuration to distinguish one word from another and/or to signal grammatical differences.
Traditionally, tone languages were divided into level tone languages and dynamic tone languages. The former use only differences in pitch level, while the latter have at least some pitch configurations (rises, falls etc.) in the tonal inventory. More recent analyses view all tone languages as having only tone levels. The difference between the two types of language is now captured by the maximum number of tone levels that can be associated to a single tone-bearing unit in a language. For level tone languages the maximum is one. Dynamic tone languages allow more than one tone per tone-bearing unit.
The pitch differences between tones are quite frequently accompanied by other features such as differences in duration or in phonation type.
An example of a lexical tone language is Vietnamese. Northern Vietnamese, at the phonetic level at least, has six tone patterns. Here they are with examples given in Vietnamese orthography:
- Mid level ta I, we
- Low falling (often with breathy voice) tà fall
- High rising tá 12 units
- Mid falling-rising tả to describe
- High broken rising tã diaper
- Short low falling tạ 100 kg
Number 5 is a rise interrupted by a glottal stop.