Listen to this example of kulning (short mp3file).
"Herding calls from Gammelboning -
In this song a special high-pitched vocal technique is used called kulning, a vocal means of expression mainly used by women in the grazing pastures in Scandinavia. It has been used since the Middle Ages and functions primarily as a means of communication between the shepherdess and the animals and can be heard many miles away."
Even more here.