It's really difficult to push the "Uhura is a skilled linguist" angle when Star Trek has the Universal Translator, and when TOS never showed Uhura with a penchant for languages (or for anything much).
However, I could buy it that only certain skilled people would be able to pick up a scrambled voice transmission and identify which language it was scrambled from. And by scrambling I mean both natural degradation of signal, and deliberate efforts at ciphering. It's another question whether a starship communications officer would be expected to have such skills or not.
Tee hee - Uhura couldn't even speak basic Klingon in TUC! It was a joke scene and it was funny but it was as insulting to the character as the fact that Chekov, a former security chief in TMP, didn't know that weapons fire would set off the alarms.
This is also something I alluded to earlier about Spock doing linguistic translations and code cracking in TOS when Uhura should have been a front-runner.
I agree that a throwaway line about interference making the translator unreliable would have made Uhura's role worthwhile.