What "r" you doing?
Please discuss the "r" phoneme as well as its allophones in Spanish. When I expect non-trill "r's," I hear trill "r's". Why is this so unpredictable? Are their fast, hard rules for pronounce "r"?
5 Answers
You roll your "R" if "R" is the first letter of a word or if there is a double r [rr].
Perro - the guy in the video translation pronounces it with a lovely trill.
Regresar - listen to the video translation
When "R" is not the first letter or if there is not an "rr", the Spanish "r" sounds like the English "d" (in Spain, anyway).
Pero - listen to the video translation!
For more information regarding rolling r's, please read here.
I agree 100% with Sonrisa, but would just add that if this question is coming up because of conversations with people, sometimes its just part of the way people speak, or I know that in Mexico the mexicans will do it around the americans who come to visit to give them a hard time, and sometime when people speak fast they sound like they are rolled, when in fact they are not. So you MIGHT be hearing them when they are not supposed to be there, because of the people who you are speaking with speaking incorrectly. Same way there are different ways we say certain sounds in different parts of the states or canada in english, diferent people and places in latin american will pronounce things slightly more or slightly less exaggerated.
Why is this so unpredictable?
It is 100% predictable. At the beginning of a word or after N, L or S, a single letter R has the strong trilled sound. In all other cases, a single R is pronounced like an alveolar flap, very close to the alveolar tap of the American English of the T in "better". The RR is always trilled.
Varies per region. What Sonrisa says is the general rule and if you apply that then you're PROBABLY not going to be made fun of, but I've heard native speakers who also roll every r that is at the beginning of a syllable. These were all Mexicans, who seem to be proud of their r's (and are frequently mocked for it in South Park).
On the other hand, people on my Spain tv channel sometimes don't even roll the double r's.
They are not allophones. There are two phonemes (consider the minimal pair "pero" and "perro"). However Spanish orthography is somewhat inconsistent in that the trilled phoneme is not always represented by "rr".