followed by another consonant except (normally) a liquid or semivowel in the same word, as in mattress. Another possibility is pre-glottalization (or glottal reinforcement), where a glottal stop is inserted before a syllable-final stop, rather than replacing it. That can happen before , and or also before the affricate . It can occur in RP in the same environments as those mentioned above, without the final restriction so a glottal stop may appear before the , as in mattress. It can also occur before a pause as in quite! spoken alone but not in quite easy. In the case of , pre-glottalization is common even before a vowel, as in teacher. According to Wells, this pre-glottalization originated in the 20th century (at least, it was not recorded until then). Glottalization of spread rapidly during the 20th century. S-cluster metathesis Final consonant clusters starting with sometimes undergo metathesis, meaning that the order of the consonants is switched. For example, the word ask may be pronounced like "ax", with the and the switched. This example has a long history: the Old English verb áscian also appeared as acsian, and both forms continued into Middle English, the latter, metathesizing to "ask". The form axe appears in Chaucer: "I axe, why the fyfte man Was nought housband to the Samaritan?" (Wife of Bath's Prologue, 1386), and was considered acceptable in literary English until about 1600. It persists in some dialects of rural England as well as in Ulster Scots as , and in Jamaican English as , from where it has entered London English as . S-cluster metathesis has been observed in some forms of African American Vernacular English, although it is not universal, one of the most stigmatized features of AAVE and often commented on by teachers. Examples of possible AAVE pronunciations include: Merger of /str/ and /skr/ For some speakers of African American Vernacular English, the consonant cluster is pronounced as . For example, the word street'' may be pronounced as . The form has been found to occur in Gullah and in the speech of some young African Americans born in the Southern United States. It is reported to be a highly stigmatized feature, with children who use it often being referred to speech pathologists. Yod-rhotacization Yod-rhotacization is a process that occurs for some Memphis AAVE speakers, where is rhotacized to in consonant clusters, causing pronunciations like: Compare yod-dropping and yod-coalescence,