a) Today I am really croaky, I am almost out of voice. Today I am really croaky, I HAVE almost LOST MY voice. The other options all work well but: a) Today my voice is very croaky. b) Today my voice is very hoarse. are probably more commonly used. Croaky would be more informal but they both mean the same thing. Lily

You say 'lost your voice', not 'out of voice'. 'I have almost lost my voice', or if you can't speak at all, 'I have lost my voice.' You can use 'to be' e.g. I am losing my voice, but as you can see this is present continuous and isn't appropriate for what you were trying to say before. Anyway I don't think there is a big difference between 'croaky' and 'hoarse' as adjectives here. Your latter two options 'Today my voice is very croaky/hoarse' sound more natural to me. 'Hoarse' can also be used if you have damaged your voice by shouting. Myself, I would probably just use the word 'bad' instead to describe this feeling. I have a bad throat today. My voice is bad today.