You can also study Tristan's vocabulary developing in this video he is making car and dog noises and at the end he is trying to say "csüccs" which means sit in Hungarian. He loves to sit on someones lap and going through books, our little bookworm :)
He also recognizes cats and fishes and makes funny noises for them, he says "dada" for the ball and today's newcome is the chicken noise in sort of Welsh "cot-cot-cot". We realised that at the moment he says things in one language and always picks the easier one. There are going to be some funny sentences in the future I bet!