You would think after his experience with his wish gone wrong in the story of the golden touch that perhaps King Midas would have acquired a little common sense.
But .. as the story goes ...
Once upon a time, a long time ago, Pan, the god of shepherds, challenged Apollo to a musical duel. Pan insisted his flute of reeds could produce a more beautiful melody than Apollo's silly harp. The two agreed on a contest with judges. One of the judges was King Midas.
After hearing the two melodies, all but one of the judges chose Apollo as the winner. But one judge, King Midas, preferred Pan's tune.
Furious that anyone could prefer a reedy pipe to his musical lyre, Apollo cooed, "I see the problem. It's your ears. They are too small to hear properly. Let me fix that for you."
King Midas felt his ears quiver. His ears sprang out, and out, and turned into the large furry ears of an ass. King Midas was horrified. He grabbed his ears. "Pan, help me!" he cried. But Pan, with a quick nervous glance at Apollo, turned his back.
King Midas tried to hide his ears from his subjects by wearing a variety of huge hats, heavy helmets, and bulky scarves. The only person who saw his ears was his barber. King Midas made his barber promise he would never tell a soul.
His barber kept his word. But keeping such a huge secret to himself was driving him crazy. Finally, the barber went up a mountain and almost to the edge of a cliff. He dug a hole in the midst of some reeds. He looked about, to make sure no one was near. Then, he whispered into the hole, "King Midas has the ears of an ass. King's aaaass ears! King's aaaass ears!" Having gotten his secret off his chest, he felt much better. He returned home, sure that he had kept his word.
Unfortunately for King Midas, the barber had dug right into a piece of Echo. You've heard of Echo, right? Pieces of Echo were scattered all over the mountainous kingdom. In fact, pieces of Echo were scattered all over the world.
Although I suppose some people might think it was only the sound of the wind in the reeds, it was really a piece of Echo, whispering over and over, "King's aaaass ears, king's aaaass ears".
Sound travels well in the mountains, even whispers. It was not long before the entire kingdom knew the king's secret.