What noise does capote hear while the other passengers are sleeping?

In Truman Capote's "In Cold Blood," while the other passengers are sleeping, he hears the soft, rhythmic sound of the train wheels on the tracks, which creates a soothing yet eerie atmosphere. Additionally, he becomes aware of the occasional clatter and creaks of the train itself, heightening his sense of isolation and introspection during the journey. This auditory backdrop underscores the tension and anticipation of his surroundings.