Information and Research by Becci Jewell
Burst-pulse sounds, or buzzes, are actually composed of individual clicks but the repetition rate is so high that the clicks are indistinguishable to humans and it sounds like a continuous noise.
Buzzes are produced by toothed whales and are often associated with feeding and close range social interactions. Porpoise search for prey in a vertical position and use echolocation to detect prey. A burst pulse sound is a close range echolocation.
The amplitude (loudness) of echolocation clicks produced by porpoise are much lower that those produced by dolphins. This means that porpoise have a smaller detection range when they are looking for food and navigating around the sea.