world's Spanish speakers (more than 112 million of the total of more than 500 million, according to the table above). One of its main features is the reduction or loss of unstressed vowels, mainly when they are in contact with the sound /s/. In Spain, northern dialects are popularly thought of as closer to the standard, although positive attitudes toward southern dialects have increased significantly in the last 50 years. The speech from the educated classes of Madrid is the standard variety for use on radio and television in Spain and it is indicated by many as the one that has most influenced the written standard for Spanish. Central (European) Spanish speech patterns have been noted to be in the process of merging with more innovative southern varieties (including Eastern Andalusian and Murcian), as an emerging interdialectal levelled koine buffered between the Madrid's traditional national standard and the Seville speech trends. Phonology The four main phonological divisions are based respectively on (1) the phoneme ("theta"), (2) the debuccalization of syllable-final , (3) the sound of the spelled , (4) and the phoneme ("turned y"), The phoneme (spelled before or and spelled elsewhere), a voiceless dental fricative as in English thing, is maintained by a majority of Spain's population, especially in the northern and central parts of the country. In other areas (some parts of southern Spain, the Canary Islands, and the Americas), does not exist and occurs instead. The maintenance of phonemic contrast is called in Spanish, while the merger is generally called (in reference to the usual realization of the merged phoneme as ) or, occasionally, (referring to its interdental realization, , in some parts of southern Spain). In most of Hispanic America, the spelled before or , and spelled is always pronounced as a voiceless dental sibilant. The debuccalization (pronunciation as , or loss) of syllable-final is associated with the southern half of Spain and lowland Americas: Central America (except central Costa Rica and Guatemala), the Caribbean, coastal areas of southern Mexico, and South America except Andean highlands. Debuccalization is frequently called "aspiration" in English, and in Spanish. When there is no debuccalization, the syllable-final is pronounced as voiceless "apico-alveolar" sibilant or as a voiceless dental sibilant in the same fashion as in the next paragraph. The sound that corresponds to the letter is pronounced in northern and central Spain as a voiceless "apico-alveolar" sibilant (also described acoustically