What causes bottom end noise

[Canuck 93 Civic Si]

I started getting some bottom end noise a little while ago and decided to pull the mains to measure them.

This is what i found...

Im actually kinda suprised they didnt make more noise. I think that the owner before me overheated the engine and cooked a few of the bearings, what do you guys think?

 

[B16]

what does this bottom end noise sound like? and at what rpms?

 

[Canuck 93 Civic Si]

You can hear this noise at any rpm, it gets louder as you start to load up the engine. Basicly what you are hearing is a knock that is made when the crank shaft is banging around in the main bearings because they are too loose or its the rod bearings banging around the crank journal because they are too loose. Either way its just a knocking sound