If you filter out the echo..it sounds very much like the sounds we heard when Mvula and his lady friend were around.  In fact on the same evening of this recording, we did hear a leopard...assuming it was Mvula because the sounds were identical to the ones we heard on the video of the two leopards a few days before.  On the night of this recording, the leopard we could hear was off cam, but very near the mic as we listened. Perhaps both mics were picking up the sound and echoing? Just my thoughts...would love to know what the rangers think.

Just my thoughts

Because it was together with the lightning, for me it seems to be the thunder rolling to NK with an "echoing effect" Did see and heard it in real SA time to.

very interesting sounds but I don't have a clue what could be making them.  Hope maybe one of the rangers might know.