As far as I've seen the original location where China heard their pings has never been searched.
There were initial reports that some of the first video releases of the china pings found via a fishing rod and rubber raft and mike in the water also showed on one side a hand held transmitter set on freq. Later video supposedly had cropped that potion out.
And as I recall- some sort of surface search for debris was made in that same area by a few ships before moving to the more north ( current ) area.