Sound Around is a magazine story.
The Fat Controller had arranged a special sound tour for some local schoolchildren. They were very excited about it. Every time Gordon blew his whistle throughout the journey, the children would hear a mystery noise and have to guess what it was. First Gordon passed a church where the children heard bells ringing. Then they passed a police station and a siren replied to Gordon's whistle. Next up was the airport where they heard some planes. Finally Gordon returned to the station where tea had been prepared. Gordon dropped the children off and then raced away to do another job.
Later, as Gordon steamed through a small forest, a branch snapped from a tree and hit him. When Gordon returned to pick up the children, he blew his whistle loudly, but the children did not recognise the sound. It becomes clear that the branch had broken the big engine's whistle. The children laughed; it was the only sound they had not been able to guess.