What physical structure in bats functions as the fastest-contracting muscle known in any mammal?

Answer

The larynx

The larynx is the physical mechanism producing the rapid-fire calls, and it is the fastest-contracting muscle known in any mammal, capable of contracting 200 times per second.

What physical structure in bats functions as the fastest-contracting muscle known in any mammal?
mammalflightabilitybatecholocation