loud cough/bark?

Evening, I have a hen who has made a loud shrill cough/bark sound, this is when she has been pecking around it doesn't seem to worry her and she only does it once at a time any suggestions?
Also I would like to say thankyou to 'joyfull' who has helped from their advice on aggressive feather pulling and eating, 'touch wood' your advice to get ex-batt feed so far has worked

hmmm, my Mrs Plum does that too, and has done for nearly a year. I have never got to the bottom of her croak, but it hasnt got any better OR worse through this time, if that helps any?