In two excruciating posts (here and here), Madrid blogger Andrés Adrover Kvamsdal described his months-long quest to master his native language’s trilled r sound, a journey that involved surgery followed by months of daily speech therapy. It’s clear from the responses to these posts that Sr. Adrover isn’t alone.
I haven’t been able to find any statistics on r problems among adult speakers of Spanish, but there’s no doubt that the trilled r is a hard sound to learn. About ten percent of Spanish-speaking children don’t master it until age six or seven, and almost six percent are still working on the sound in their “tween” years. People with r problems substitute a tap for the trill (that’s what I do, alas), or even an entirely different sound (d or g). Some speakers produce a trill, but “cheat” by trilling the back of the tongue, French-style, instead of the tongue tip, or muddy the sound by involving other articulators (lips, cheeks, etc.) along with the tongue.
Spanish speech therapists usually start by putting their clients through a series of “tongue calisthenics” to strengthen the muscle. The usual technique for mastering the trill itself is to gradually morph an easier type of tongue vibration toward the Spanish norm, e.g. working forward from a French trill or backward from a “Bronx cheer”. Therapists also use a variety of props to help their clients find the correct tongue position and movement. These include mirrors, tongue depressors, and electric toothbrushes — or vibrators, as a Brazilian friend once recommended to me with utter seriousness.
A few summers ago I worked diligently on my own r, using the work-it-forward method. (This is also called the tiger method because you sound like a sick tiger.) After intensive practice I was able to get my tongue tip to vibrate, but could never learn to use the vibration in actual speech. At least I can console myself with the knowledge that some native speakers have the same problem. Misery loves company!