An elderly woman is complaining to her doctor that, though she has a lot of gas, when she passes it, it makes no sound, and there is no longer any smell. She asks if this means that there is something wrong with her digestion. The doctor nods sagely and writes her a prescription.
A week later, the woman returns, with the complaint that the medicine made her gas stink, but otherwise there was no change.
The doctor tells her, "Now that we have your sinuses cleared up, let's see about getting you a hearing aid."