The tiger hears the last voice, which is the sound of the patrolling cars at night.
The poem describes a tiger in a zoo, contrasting its natural habitat with its confined existence. This contrast is highlighted by the sounds the tiger hears. During the day, it might hear the noises of the zoo visitors. However, at night, when the zoo is closed and quiet, the dominant sound is the "last voice" of the patrolling cars. This symbolizes the tiger's captivity and the ever-present control of humans. The patrolling cars represent the artificial environment the tiger is forced to inhabit, a far cry from the natural sounds of the jungle it would otherwise experience. The sound of these cars serves as a constant reminder of its imprisonment.
