Sound is a verb, so you can say "the computer sounds the noise" But can you say, "the letter K sounds kuh" and "what does the letter K sound?"
I understand you can say "what does K sound like, what is the sound of K, etc." but when trying to make that sentence as simple as possible, asking "what does the letter sound?" and "the Letter sounds __" seems grammatically correct, but doesn't feel like its correct. sounds very weird to me.
So is my sentence correct? and if it isn't, what would be the absolute simplest way to ask and answer that question.