'minister'. In syllable-final position inside a word, the tap is more frequent, but the trill can also occur (especially in emphatic or oratorical style) with no semantic difference—thus arma ('weapon') may be either (tap) or (trill). In word-final position the rhotic is usually: either a tap or a trill when followed by a consonant or a pause, as in amo paterno ('paternal love'), the former being more common; a tap when followed by a vowel-initial word, as in amo eterno ('eternal love'). Morphologically, a word-final rhotic always corresponds to the tapped in related words. Thus the word 'smell' is related to 'smells, smelly' and not to . When two rhotics occur consecutively across a word or prefix boundary, they result in one trill, so that da rocas ('s/he gives rocks') and dar rocas ('to give rocks') are either neutralized, or distinguished by a longer trill in the latter phrase. The tap/trill alternation has prompted a number of authors to postulate a single underlying rhotic; the intervocalic contrast then results from gemination (e.g. tierra > 'earth'). Obstruents The phonemes , , and become voiced before voiced consonants as in jazmín ('Jasmine') , rasgo ('feature') , and Afganistán ('Afghanistan') . There is a certain amount of free variation in this so that jazmín can be pronounced or . Both in casual and in formal speech, there is no phonemic contrast between voiced and voiceless consonants placed in syllable-final position. The merged phoneme is typically pronounced as a relaxed, voiced fricative or approximant, although a variety of other realizations are also possible. So the clusters -bt- and -pt- in the words obtener and optimista are pronounced exactly the same way: obtener optimista Similarly, the spellings -dm- and -tm- are often merged in pronunciation, as well as -gd- and -cd-: adminículo atmosférico amígdala anécdota Vowels Spanish has five phonemic vowels, , , , and (the same ones that are found in Asturian-Leonese, Aragonese, and also Basque). There is no phonemic distinction between the close-mid and open-mid vowels that is found in Catalan, French, Italian and Portuguese. There is, however, an alternation between the plain mid vowels and the opening diphthongs (with occurring instead of in the word-initial position) that is similar to the distinction between the close and the open in the aforementioned languages; compare heló 'it froze' and tostó 'he toasted' with hiela 'it freezes' and tuesto 'I toast'. The diphthongal regularly correspond