The Spanish Pronunciation Guide:

Consonant > II < Consonant


In these instances, the word boundaries are clearly heard, because the natural occlusion that occurs in the mouth on the ending consonant of one word and on the beginning consonant of the next one keeps them audibly separate--unless the two consecutive consonants in question are identical--as in "también >||< nos," in the first example, or "los >||< sonidos," in the third--in which case the repeated consonant will normally be heard as a slightly elongated single one. Reminder: A word beginning with an h, which operates as a consonant for purposes of syllabication but which nevertheless has no phonetic value in Spanish, would obviously be treated, in the oral delivery of a complete phrase, as if the word began with a vowel, e.g., dos horas would sound like do / so / ras.