The Whistling Language of Aas in the Ossau Valley

Aas is the Occitan name of a French village of about a hundred inhabitants in the commune of Eaux-Bonnes, Ossau valley, the historical province of Haut-Béarn.

Its shepherds maintained a whistled language until the 20th century. According to Graham Robb, no outsiders knew of the language until a 1959 TV program mentioned it. 

Whistles were up to 100 decibels, and were used for communication by shepherds in the mountains and by women working in the fields. 

During the Nazi occupation the language was used to ferry refugees across the Spanish borders.