impossible for humans to detect footsteps

Larten stopped humming and kept his gaze on the roasting cat. He
appeared to be listening to the crackle of the flames, but he was actually
concentrating on very soft steps behind him.

“Will you be dining with us tonight, sir?” he called, without looking up
from the fire or turning around.

Someone clapped. “Very good,” the stranger said, stepping forward out
of the shadows. “You have a sharp ear.”

“For a human,” Larten murmured, and turned to greet the visitor. He’d
known by the sounds that their guest was a vampire—he moved in the same
quiet way Seba did when he was testing Larten’s senses. If a vampire
wished to sneak up on a human, they could move so silently that detection
was impossible. But this one had wanted to give Larten a chance.

***

The Saga of Larten Crepsley: Birth of a Killer, Chapter 8