Why did my car horn change pitch?

I drive a 2009 Ford Escape XLT and the horn will sometimes become higher pitched in the winter cold, but go back to normal in a couple of days. This time, however, still in the summer, it has gotten very high pitched and has stayed that way for a week or two. Will it go back to normal? Is there something wrong with it?

Does the car actually have 2 horns that activate together? With different tones. One may not be working, so you only hear the higher pitched tone.

I had this problem once when I parked my car with the nose in a deep puddle and the horn filled with water.

You probably have two horns. One is conking out.

Did you buy this car from Bruce Jenner? Just sayin'

It must be the pollen in the air. You horn goes hoarse.