Are you talking about tones as in tonal languages? If there are any tonal changes of this kind, they are involuntary, because the German language has no tones. As Susanne said, there is actually no /g/ sound in the word "Hunger". And if I compare it to the pronunciation of "Hummer", I hear no difference apart from the consonant in the middle.

The German "ng" in "Hunger", "singen" or "Wange" is pretty similar to the "ng" in "walking", it's represented by /ŋ/ in the IPA. I.e. it's more of a nasal /n/, the "g" almost disappears. If the "g" is preceded and followed by a vowel as in "Liege", it's the same as at the beginning of a word ("Glocke"), i.e. the same as the English /g/ in "get", unless the word ends in "en" ("legen", "liegen", "lagen"), then many (if not most) Germans don't pronounce the last syllable as /gən/, but instead turn it into a nasal /gn/, dropping the e/schwa altogether. If a word ends with a "g" as in "Weg" (path), it turns into a /k/ sound (but you probably know that already). Hope that helps!

German is not my first language, but as far as I am aware there are no 'rules' for this. Take a word like 'gegangen' it has two games in the middle ( ignore the first letter for this explanation). There is very little difference between the pronunciation of the first g and the second. The second g might sound a little different because of the n in front of it, and the first a little different syllabic emphasis on the first g.