The other sound is partial disc stall, caused from a cyclic input of too high a rate for the blade to keep up.
The area of the disc being commanded to move the most in the cycle is where the partial stall will occure, and where the sound will come from.
Mine happened through a very high rate emergency cyclic input, on heavy rotors with low rpm, and from memory, it came from between about 7 and 5 oclock, the area of disc that was commanded to move the most in a hard left.
The only 'damage' i noticed, many months later, was 'bruised' cheek plates on one of the rotors.
I wouldnt say you didnt experiance a stall, but id think it was more likely a serious wake slap.
BUT, either way, its usualy more than one crack you hear. Wake slaps can last for several seconds with many cracks, and the stall i had had roughtly 4-5 cracking sounds.
Chuck Beaty described the sound best as that of a boat paddle be'n slapped hard on to water, sideways.