When I was helping out at a vets a vet said a cat was deaf as they did similar tests but the vet soon pronounced him as able to hear when I rustled a bag in an adjoining room as the cat spun round and started mewing so the vet came through and asked me what I did so told him. The vet went back in the room turned the cat so its bottom was facing me and told me to do it again and the cat again spun around, some cats just ignore certain sounds lol