Children use growling and cooing to communicate

Amstetten: The Austrian children locked in a windowless dungeon for their entire lives evolved their own feral language using animalistic growling and cooing noises, police said.

Stefan Fritzl, 18, and his brother Felix, 5, learned to talk by watching TV in the dank cellar where they were held with their mother Elisabeth Fritzl, 42.

Leopold Etz, the Amstetten police chief, said: "They communicate with noises that are a mixture of growling and cooing."

Dr Berthold Kepplinger, who examined the brothers at a neuropsychiatric clinic near Amstetten, said: "Their mother taught them to read and write a bit but Elisabeth had lost much of her childhood knowledge after her imprisonment from the age of 18. They had no books and the main source of education was the television."

When rescued last week Felix pointed to the moon, which he was seeing for the first time, and said: "Is that God up there?''

He then made excited gurgling noises when he saw a cow. He is constantly excited and keeps trying to hit the air with his hand.

When he saw the sun he made a squeaking noise. Police took him in a lift at the hospital and he was petrified. He was stunned when an officer talked into a mobile phone.

Stefan and Felix's sister Kerstin, 19, fell ill in the cellar and is in a coma. All three have weakened immune systems, vitamin D deficiency, cramped posture and are anaemic. Kerstin has lost most of her teeth.

- The Telegraph Group Limited, London 2008