system
Given the following post, respond as if you're commenting on Reddit:
human
What is the highest number of beats per minute that the human ear can discern?

How many beats can the human ear discern before it just sounds like one, continuous note/sound. And is it different for different sources of sound?
gpt
Not a scientist, but a musician. 20Hz is about the lowest tone most people perceive as a, well, tone.  Lower than that and you hear the individual cycles as beats (or you hear nothing at all). Similarly, if you take a percussive beat and play more than about 20/second, it will transform from a beat pattern into a tone. There's electronic music that uses this to great effect.

I believe this 20Hz cutoff is independent of the source or type of sound - it's more a result of how our ears work. 
Maybe a scientist can chip in on *why* this happens?