If you haven't separated her from the rest of the flock, please do so.
I would plan on worming her as the noise might be gape worms. Do a search on here for valbazen, it is the best all around womer there is. Repeat in 2 weeks.
Here is a link to my hens that had raspy cough. It turned out to be parasite related: https://www.backyardchickens.com/forum/viewtopic.php?id=576036&p=1
My hen made that same sound for a few hours one day. then she stoped. I called the vet and asked her about it.
she said that there could have been somthing stuck in her throat.
My hens sounded raspy and had a hiccupy cough....they didn't sound normal. It was my first clue that something was wrong. They had a secondary from the worms that weakened their immune system so much.