The way one can learn to say ř is to whisper very very quietly r in a long sequence... rrrrrr. Not [ar] but "just" hard r. Over time, this rolling r can become

The way one can learn to say ř is to whisper very very quietly r in a long sequence... rrrrrr. Not [ar] but "just" hard r. Over time, this rolling r can become ř. Children take several months to learn pronouncing it.