Rengar Ult (R) Bug [GAMEPLAY]

I do not know if this is intentional or not, however In the few games Ive been in as of late Ive noticed that if an enemy Rengar uses his ultimate off screen and while in FoW, you do not get the heat beat sound affect when he is near you over a wall. I have not been keeping up with the patch notes, so I'm fully aware that there may have been changes to him since I last played (before the Pre-season). I have not personally reproduced the bug, however from what I've observed, Rengar needs to be off screen and in FoW. Then, the enemy Rengar can run up to A champion he is targeting from behind a wall and the targeted champion will not here the tell-tell signs of an approaching/near Rengar.