Ah, the tricky /rl/!
Research shows that the /rl/ combination is the most frequently misproduced sound, almost 3x more likely to be incorrect than /ear/ combinations. Why?
1. The /l/ in /rl/ is sometimes called the “dark” /l/, because its production occurs completely inside the mouth (thus no visual cues)
2. The /r/ and /l/ are both liquids or guide sounds, thus they are both complex and changing to descrivbe and produce.
3. The place of articulation for the sounds is in different parts of the mouth, so it’s necessary to make a rapid transition. The /r/ is in the middle to back part of the mouth and the /l/ is more toward the front.
How do you correct the /r/ combination?
First suggestion is to tackle other vocalic /r/ sounds first, save the /rl/ for last so that success is built up and possibly generalization might either correct it or at least soften the severity of it’s misproduction.
Second, be patient.
Third, break the sounds down to component phonemes. Since there are no words that begin with the dark /l/ phoneme, it is difficult to employ co-articulation with medial and final rl. So you’ll just have to work with what you have. You can divide up /ger/ + /l/ for girl. Break it down, go slow and build up to normal cadence.
What suggestions do you have?