During the advents week before X-mas till the 6th of januar you can hear the horns blowing in the east part of the Netherlands (where I grew up). It's a very old tradition.
But how old? There are different opinions about it. Some say 1500 A.D. is assumed the first year that they blow the midwinter horns, some say it started during the dark ages. There is document of 1815 in the county archive that mention midwinter horn blowers. A father and son were accused of warning smugglers by using their midwinter horns.
They blow the horns to chase the evil spirits and ghosts away, and to welcome springtime, a new beginning. But it's also a way to communicate, when you hear the horn of the next village, you answer it with horn blowing.
By the way, it's not done when you blow the horn when somebody else is blowing.
This sunday you could hear the horn blowers in the woods of Exel. It gives a very special feeling walking in the woods, grey and cloudy, and hear the horns .