Of Ghouls and Marbles

After posting my previous post on the sounds of marbles in HDB houses, I did some research, and found that Asia 1 had conducted a poll on their website, asking: "Do you sometimes hear the sound of dropping marbles in the HDB unit above yours in the middle of the night?", to which an amazing 65.7% said "Yes". Even discounting that a number of the Yes responses may be jokes, it still looks like a large number.

I also found that this phenomenon has been reported and discussed quite a lot in the past.

Some of the more interesting (not necessarily sane) hypotheses:

haha... anyway I've heard 2 kinds of explanation. The rational/ scientific one is the expansion and contraction of the steel in the reinforced concrete that most HDB flats are built with due to temperature fluctuations. I do wonder though why this phenomenon is less observed in private housing.

The 2nd, more "paranormal" explanation is that during the construction of HDB flats the construction workers/ foremen actually put in some marbles when pouring the concrete. These marbles are for the spirits that may be around, so they will play with the marbles instead of disturbing the human occupants of the place. *shrug* Anyone knows a construction foreman?

And here's another similar one:

... when they build the HDB flats, they will leave an empty space in between the floor and the next floor's ceilings, and they will put marbles into that empty space. It is for the spirits to play with ...

And one that may make more sense, though I can't imagine re-bars sounding like bouncing marbles:

... there are reinforced iron rods inside the concrete. During day time they expand due to heat, night time they contract.... That's why there is sound occurred [sic] at night... when iron rods contracted.

Still quite spookay.