At the sound of my greeting, ...(Para. 7)
at the sound of...: when I heard ...
At the sound of steps, the chief ran away. 听到脚步声，小偷逃走了。
At the sound of the train, the children jumped with joy, as they knew they could see their father soon. 听到火车声，孩子们欣喜雀跃，因为他们知道很快能见到他们的父亲了。