Definition of "throbbing"

Krause’s “niche hypothesis” may seem more plausible after you’ve listened to his recordings of dense tropical jungles, polyphonous soundscapes packed with whistles and whinnies, whoops, hoots and howls, deep bass throbbings and shrieking buzzes.

2007 February 18, Jeff Hull, “The Noises of Nature”, in New York Times‎