Get a long screwdriver and hold the handle end to your ear and touch the other end of the screwdriver to various areas of the engine as the engine is being revved. That should help you locate whereabouts on the engine the noise maybe coming from.

Little end refers to the bearing that the gudgeon pin in the pistons fits into and rotates around.



https://www.youtube.com/watch?v=KCHNGlpMUOA

Usually if it's big end or main bearing the knocking occurs as the engine is revving up rather than dropping back down and it's louder.