Most dialects that merge the two sounds represented by and realize the remaining sound as a voiced palatal fricative, which is similar to the in English your, but it sometimes sounds like in English jar, especially after or or at the beginning of a word. For example, relleno is pronounced and conllevar is pronounced or.
''Zheísmo'' and ''sheísmo''
In most of Argentina and Uruguay, the merged sound is pronounced as a sibilant ; this is referred to as zheísmo. In Buenos Aires, the sound has recently been devoiced to among younger speakers. Rioplatense does not, however, use the sibilant sound for word-initial . Therefore hierro is distinct from yerro. These two words are merged in most other varieties of Spanish. The same shift from to to historically occurred in the development of Old Spanish; this accounts for such pairings as Spanish mujer vs Portuguese mulher, ojo vs olho, hija vs filha and so on.
Extension of ''yeísmo''
Currently, the highlands of Colombia are shifting to yeísmo with older people being the only keeping the distinction, which is completely lost in people born in the 1980s onwards. The distinction between and remains in the Philippines, Ecuadorian highlands, Andean Peru, Paraguay, Bolivia, and the northeastern portions of Argentina that border with Paraguay. The distinction is more common in areas with a common bilingualism with indigenous languages, such as Aymara, Quechua, and Guaraní. In Spain, most of the northern half of the country and several areas in the south used to retain the distinction, but yeísmo has spread throughout the country, and the distinction is now lost in most of Spain, particularly outside areas with linguistic contact with Catalan and Basque.
Minimal pairs
Yeísmo produces homophony in a number of cases. For example, the following word pairs sound the same to speakers of dialects with yeísmo, but they would be minimal pairs in regions with distinction:
haya ~ halla
cayó ~ calló
hoya ~ olla
baya / vaya ~ valla
The relatively low frequency of both and makes confusion unlikely. However, orthographic mistakes are common. A notable case is the name of the island of Mallorca: since Mallorcans tend to pronounce intervocalic /ʎ/ as /j/, central Catalan scribes assumed the authentic name Maiorca was another case of this and hypercorrected it to Mallorca. This new form ended up becoming the usual pronunciation, even for native Mallorcans.
Similar phenomena in other languages
Romance languages
Standard Portuguese distinguishes, and. Many speakers merge and, making and both. Some speakers, mainly of the Caipira dialect of Brazil, merge and, making and both. Some Caipira speakers distinguish etymological and, pronouncing olho and óleo.
In French, historical turned into, but the spelling was preserved, hence briller, Versailles.
