Which human sound does the assonance between fast and pants echo in these lines from Kubla Kahn by Samuel Taylor Coleridge?

The assonance between "fast" and "pants" in these lines from "Kubla Khan" by Samuel Taylor Coleridge echoes the sound of someone breathing quickly or panting, which conveys a sense of urgency or agitation. This assonance enhances the feeling of tension and excitement in the poem's imagery.