rural Michoacan, , represented by , tends to be deaffricated to , a phonetic feature also typical of southwestern Andalusian Spanish dialects. All varieties of Mexican Spanish are characterized by yeísmo: the letters and correspond to the same phoneme, . That phoneme, in most variants of Mexican Spanish, is pronounced as either a palatal fricative or an approximant in most cases, although after a pause it is instead realized as an affricate . In the north and in rural Michoacan, is consistently rendered as an approximant and may even be elided when between vowels and in contact with or , as in 'hen', 'chair, 'seal'. As in all American dialects of Spanish, Mexican Spanish has seseo, so is not distinguished from . Thus, 'house' and 'hunt' are homophones. Present in most of the interior of Mexico is the preservation, or absence of debuccalization of syllable-final . The fact that the areas with the strongest preservation of final are also those with the most frequent unstressed vowel reduction gives the sibilant a special prominence in these dialects. On the other hand, -weakening is very frequent on the Pacific and Caribbean coasts, and is also fairly frequent in northern and northwestern Mexico, and in parts of Oaxaca and the Yucatan peninsula. In all these regions, -weakening acts as a sociolinguistic marker, being more prevalent in rural areas and among the lower classes. The prevalence of a weakened syllable-final in so many peripheral areas of Mexico suggests that such weakening was at one point more prevalent in peripheral areas, but that the influence of Mexico City has led to the diffusion of a style of pronunciation without -weakening, especially among the urban middle classes. -weakening on both the Pacific and the Gulf Coast was strengthened by influences from Andalusian, Canarian, and Caribbean Spanish dialects. Also, the dialects spoken in rural Chihuahua, Sonora, and Sinaloa, like that of New Mexico, have developed aspiration of syllable-initial , as in words like 'to pass' and 'sir'. Despite the general lack of s-aspiration in the center of the country, is often elided before or , and the phrase is often pronounced without the first . Stops There is a set of voiced obstruents—, , , and sometimes —which alternate between approximant and plosive allophones depending on the environment. often becomes , especially in more rural speech, such that and may be pronounced as and . In addition,