To my gringo ear, the trilled R is the most Spanishy of the Spanish phonemes. I have been obsessed with getting this sound right, despite being told that correcting the pronunciation of other sounds - i.e. the Spanish vowels - is far more important for reducing one's accent. In addition to being rather unimportant, getting a trilled R down is difficult. It's a technique that requires effort to learn but relaxation to perform. This catch-22 is a probable cause of students going through years of Spanish schooling without being able to produce the phoneme.
But despite the low utility/difficulty ratio, I've been stubbornly focusing on this one sound. Perhaps it's because I'm convinced myself that I need to be able to do the trilled R in order to have the confidence to work on other parts of my accent.
Anyways, my stubborn efforts have been fruitful. I'm far from perfect and stumble on the trill very often, but I have more or less got the technique down. I've compiled a list of notes and links of videos surrounding the production of the trilled R for my own reference and to help anyone else who is learning this vocal technique.
I. The issue of whether the ability to make the trilled R is genetic, and why people still fail after years of trying.
There's no reason to suspect that there is a common body type that is physically incapable of producing the trilled R sound. If one is unable to produce the trilled R from a physical limitation, I am sure that someone also has other problems with speech production. Languages and their phonemes evolve over time, and since universal inclusion likely benefits the utility of a language, it is also likely that modern languages only use phonemes that can be produced by every race/gender/etc. of humans.
I believe the primary reason that people fail to achieve the trilled R is because they strain their tongue when trying. The tongue has to stay relaxed in order to "flap in the wind" (as I will describe shortly) and this relaxation is difficult when one is simultaneously putting a conscious effort to put the tongue in a new position.
II. When the trilled R should be pronounced.
(a) Any time one sees two adjacent r's in a word i.e. carretera, perro, terremoto
(b) When an r begins a Spanish word i.e. roto, ramar, realizar
(c) When an r follows an l, n, or s in a word i.e: alrededor, Ronroneo
III. The positioning of the vocal organs, specifically the tongue.
The trilled R is all about the tongue. It doesn't really matter what your jaws or lips are doing, so better to keep them both relaxed with the mouth slightly open. To learn the proper position, the best piece of advice I can give is to watch the following video from Ten Minute Spanish as well as the followup video. If the video is not an option for you, or if the link has since died, here is a summary of the proper tongue position for the Spanish R:
The tongue is raised so that the underside of the tongue touches the alveolar ridge. The center of the tongue is depressed to make a cup shape where the sides of the tongue touch the sides of the palate. Once in this position, the tongue should be incredibly relaxed.
IV. The importance of proper pulmonary airflow and avoiding glottal stops.
The trilled R is produced by the tip of the tongue flapping as the wind caused by the lungs blowing out air rushes to leave the mouth. Without sufficient air pressure, the tongue does not flap. It is hard to whisper a trilled R.
English speakers have a tendency to put glottal stops in between words. Putting glottal stops between words is a major problem that contributes to a foreign Spanish accent. The bad habit causes a specific problem with the trilled R, since the glottal stop blocks/slows down airflow to the point where the tongue does not flap.
V. Exercises that help one develop the ability to produce the trilled R.
The trilled R for an English speaker is a new muscle movement that requires some stretching and practice. These exercises will force you to do movements with the tongue that will help you find the right position and sensation for the trilled R.
Horse trot and mushroom: To do the horse trot, stick the tongue on the roof of your mouth and create a pressure pocket and flick the tongue down so it makes a clicking/trotting noise. Do this over and over again. To do the mushroom do the same movement as the trot, but create a lot of pressure with the tongue on the roof so that the tongue sticks to the roof. Then open your mouth as wide as you can to give the tongue a nice stretch.
Relax flap: Curl your tongue backwards behind your upper teeth. Then let the tongue relax completely so it unfolds itself out in front of your teeth.
VI. The difficulty of the flapped r following an l, s, and n.
Even after one has gotten the trilled R down, the lr, sr, and nr combinations remain difficult to produce. To work on these combinations I recommend watching the two following videos from Ten Minute Spanish.
Here is a video for the l->r and n->r combinations.
And here is a video for the s->r combination. The advice in this video is essentially to not even attempt the trilled r when following an s. Instead the author of the video suggests you make a "sh" sound with the r.
