Old Mrs Harris goes to her doctors with an embarrassing problem.
"I keep passing wind all the time", she explains. "It doesn't smell and it's completely silent but it's very uncomfortable" she says. "In fact it's happened about 20 times since I came in."
The doctor thinks for a while and prescribes some tablets, asking her to return in a week.
A week later Mrs Harris is back. "Those tablets have made it worse", she complains, "It's happening just as often, but now it smells too!"
"OK" says the Doctor, "Don't worry, We have to take these things gradually. Now that we've sorted out your sinus problem, we'll move on to your hearing...."