As being a learner, it'll only at any time valuable in your case to differentiate /?/ and /u:/, not /?/ and /u/, and you may do that by length.I believe There's a rule (with exceptions, naturally) about once the "ch" is throaty and when it truly is mouthy. Following an "open vowel" like "a" the "ch" us generally "throaty", after a "closed vowel" li