Eli5 – What is the difference between Subsonic sound and Infrasonic sound?

Question

Even googling it, it doesn’t make sense. I know it’s about sound that can’t be heard but….???

In: 1

Answer 1

Infrasonic is lower than audible by humans. It’s a frequency.
Subsonic is slower than the speed is sound. It’s an actual velocity that can be measured in mph.