Hi, I'm shunsuke, Japanese. I hope my answer will help you.
Just translation of this sentence into Japanese is that
"今朝、私は窓から入って来る鳥の鳴き声を聞いた。"
Sorry, I couldn't understand that this sentence means either "bird is coming through window" or "a voice is coming through window", but this translation may have both meanings. In addition, if "my window" means "my room's window", you can change "窓から" into "私の部屋の窓から" .
And we put "a voice of human being" into "声", but "a voice of animals" is usually put into "鳴き声" or "nakigoe".
Sincerely yours.