But lexical tones are, nevertheless, a popular option. Many languages of Europe, the Americas, Oceania, Africa and even Asia function perfectly well without them. Unlike consonants and vowels, lexical tones are optional 1. However, we return later to consider their phonological status and its relevance for understanding lexical tone perception by native and non-native listeners. For the following paragraphs we adopt that phonological view that lexical tones function in tone languages at the segmental level, along with consonants and vowels. Indeed, several tone phonologists claim that lexical tones function as segments in tone languages (e.g., Lin, 1989 Duanmu, 1990, 1994). While in a phonetic sense tones extend across the voiced segments of a syllable, however, such observations may not straightforwardly reflect the more abstract phonological properties of tones (e.g., see Wang, 1967 Hyman, 2011a, b). Perceptual researchers often assume tones to be suprasegmental (e.g., So and Best, 2010, 2011, 2014 Liu et al., 2018 Poltrock et al., 2018), i.e., to extend across the consonants and vowels of the target syllable. But only some languages also make use of lexical tones, contrastive sub-syllabic fundamental frequency (pitch) variations referred to as tonemes (e.g., Jones, 1944), which for those languages comprise a third class of phonemic elements. They populate the lowest level of the phonological hierarchy, the segmental tier, and both classes are obligatory across spoken languages. These two classes of phonemes are used to differentiate between words, whose meanings can be categorically changed by switching even a single vowel or consonant, as in vs. All languages employ consonants and vowels as discrete contrastive subcomponents of the basic timing units of words (syllables).

Popular text tones