The voiceless denti-alveolar sibilant is the only sibilant fricative in some dialects of Andalusian Spanish. The voiceless alveolar sibilant is a common consonant sound in vocal languages. Therefore, narrow transcriptions of the voiceless alveolo-palatal sibilant affricate include , and . Therefore, narrow transcriptions of the voiced alveolo-palatal sibilant affricate include , , and . Two notable variants occur additionally&colon; one sibilant and the other velar or uvular. It involves a marked pronunciation of sibilant consonants (particularly and ). The International Phonetic Alphabet (IPA) uses to represent a voiceless palato-alveolar sibilant. The voiceless alveolar sibilant is one of the most common sounds cross-linguistically. In linguistics, assibilation is a sound change resulting in a sibilant consonant. Some languages have only a single hushing sibilant and no hissing sibilant. Its sound value is a voiceless sibilant, or . The Chumashan languages are well known for their consonant harmony (regressive sibilant harmony). Voicing is what separates English in "bus" (unvoiced sibilant) from in "buzz" (voiced sibilant). The now-extinct Ubykh language was particularly complex, with a total of 27 sibilant consonants.