Ch

German has two ch sounds.

• ich, ech, äch, üch, öch, rch, syllable-initial — palatial ch, similar to an English sh with the lips and teeth open and the tongue relaxed

• ach, uch, och — throaty ch, similar to Russian x

This is quite logical as the vowels a, u, o are produced in the back of the mouth while the other vowels are produced in the middle or front of the mouth. The ch folllowing the vowel is produced in just the same region.

ch occurs often and is pronounced either [ç] (after ä, ai, äu, e, ei, eu, i, ö, ü and consonants; in the diminutive suffix -chen; and at the beginning of a word), [x] (after a, au, o, u), or [k] at the beginning of a word before a, o, u and consonants. Ch never occurs at the beginning of an originally German word. In borrowed words with initial Ch before front vowels (Chemie "chemistry" etc.), [ç] is considered standard. However, Upper Germans and Franconians (in the geographical sense) replace it with [k], as German as a whole does before darker vowels and consonants such as in Charakter, Christentum. Middle Germans (except Franconians) will borrow a [ʃ] from the French model. Both agree in considering each other's variant,[clarification needed] and Upper Germans also the standard in [ç], as particularly awkward and unusual.

https://en.wikipedia.org/wiki/German_language (search for consonant spellings). Using that, you can listen to the pronounciation the IPA.

Also, this describes the pronounciation using english approximations which may or may not help you: https://en.wikipedia.org/wiki/Help%3AIPA%2FStandard_German