Thirteen infrasounds

Suddenly, without a sound, without any kind of signal, all of the hounds crouched in an identical stance, and their tentacles began to vibrate all together.
“Go!” Ebenezar thundered. “Fast!”
Right. Time to get my head in the game. Maybe the cornerhounds couldn’t physically get to us, but if all thirteen of those things dropped the purely physical bass on us all at once, I was pretty sure we weren’t walking out of this garage.
In a perfect world, I could have broken the circle, rendered myself undetectable to the enemy, and just slipped aside and let the old man keep their attention while I laid down the circle and came at them.
But I’d have to make do with a birthday prank I’d been getting ready for Butters, instead.
First, step out of the circle.
As I did, the cornerhounds tensed, muscles and tendrils quivering.
At the same time, Ebenezar began to backpedal to put his back to the nearest column supporting the garage, even as he brought up another bulwark of invisible force to take shelter behind. “Come on, ye great ugly beasties!”
The cornerhounds’ tentacle heads flared out, tracking the old man, and rumbling, vibrating, subsonic thunderclaps filled the air and made me dizzy.

Peace Talks Chapter 12, Page 102


Ebenezar, meanwhile, had survived the blast of infrasound that the pack had begun to deliver just before my spell went off, and he hadn’t wasted his time since. With a single word, he pointed at the concrete floor of the parking garage, and a cloud of fine chips of rubble flew upward in a perfect circle as the old man’s will dug a trench two inches deep and four across in the obdurate flooring.

Peace Talks Chapter 12, Page 105