Yodelling started as a way for shepherds and herders to communicate across deep valleys. Their voices needed to travel a long way, so they discovered that quickly switching between two different singing voices - one normal, one very high - made a sound that bounced cleanly off the mountains. A yodel could carry a message over kilometres of empty Alpine countryside.
The alphorn is one of the longest musical instruments in the world. A traditional alphorn is around 3 to 4 metres long. It is carved from a single piece of spruce wood, hollowed out and wrapped with strips of bark to keep it strong. To play it, you blow into a small mouthpiece at one end, and a deep, beautiful sound comes booming out of the wide open end at the other.
Long ago, the alphorn was a useful tool. Herders blew it in the evening to call cows home from the meadow. They used it to signal across valleys. They even used it to wake other herders in the morning. Today it is mostly played for music - at festivals, at the start of football matches, and in concerts.
Every August, Swiss alphorn players come together for huge festivals where hundreds of them play together at once. Imagine 200 alphorns sounding all at the same time in front of a mountain - that's a Swiss summer afternoon. People say the sound is so big you can feel it in your chest.