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HDB Flat Mystery: What Is Causing The Marble Dropping Sound From Above?

Have you ever had this: It’s the middle of the night, or in the middle of the day, then suddenly you hear marbles being dropped on your ceiling.

The sound may annoy, frighten or may not even make you bulge. However for the sensitive ones, or if you are alone at home, you may think the neigbours above must not be teaching their kids well to play marbles at 1am in the morning.. Although most of us will feel fear instead.

There are many speculations on this.

Why are there marbles dropping?

Why are the kids playing marbles in the middle of the night?

When you go up and try to confront your neighbour the next day, you realise that either they are all elderly folks, or that no children are there at all, or no one is playing marbles.

Is it really human beings playing those marbles?

Is my house haunted?

Is the unit above mine haunted?

Some speculated that the go li (marble balls) are placed between the floors for the supernaturals to play so they will not disturb the occupants.

However, the acoustics in HDB is such that, if someone were to really play marbles on the level above yours, you will not be able to hear anything (much). Or it will not be as loud. Because when real marble balls hit the floor and by the time it reaches the level below, it will not be very audible.

scary blue marbles!?!?

scary blue marbles!?!? had a nice guy mentioning the change in pressure by the water flow in the toilet pipes. This vibrates the pipes and creates the clanging sound which sounds like marbles dropping.

But a more convincing urban explanation that I have personally heard is that in between the levels, and this includes the top level and the roof, there are concrete and pipes that expands and contracts during hot and cold season. And in Singapore where it can be so sunny in the day and then suddenly it rains heavily, this change of weather causes expansion and contraction to happen very quickly.

Because of this, some mechanism (or marbles, not sure are they really in ball shapes or not) were implemented to counter this. And when contraction and expansion happens and the mechanism is working, the marble sound is heard. Another explanation indicates that marble sound IS simply the expansion/contraction of the pipes and concretes.

According to Asia Paranormal Investigators (API), they also have explanations of what happened. A certain Mr Wong wrote in to The Straits Times on June 6 2005 to complain about this issue. Mr Wong previously stayed in Lorong Ah Soo but have since moved to Punggol 21.

Read the article here if you want the full story.

But the main take is what HDB says:

“HDB flats are designed based on prevailing building codes. Hence, the acoustic properties for flats are no different from other residential buildings. To date, we have not received any feedback on the sound of dropping marbles where there has not been any attributable cause. HDB Sengkang Branch Office, which manages the flats at Punggol Town, has not received any feedback about the sound of dropping marbles in the area.

In Mr Wong’s case, we have contacted him and offered HDB’s help. We will be checking with his neighbours over the next few days to see if we can locate the source of the sounds Mr Wong mentioned. Madam Shamsuddin mentioned that her eldest son described hearing similar sounds as Mr Wong. If she would like us to look into the matter too, she can contact our Toll-free Branch Office Service Line: 1800-2255-432 to provide us with her address.

In a high-rise, high-density living environment, a certain degree of noise is inevitable. It would also be in the interest of neighbourliness for residents to ensure that the activities carried out within the flat do not generate excessive noise and to exercise some degree of tolerance towards their neighbours.”

clear marble

Clear marbles.. Nostalgic?

API Explains

Real Kids Playing Real Marble

Ok, does this make sense?

As mentioned earlier, the acoustics of the HDB flats between each level make the sound of marble hitting the floor nearly inaudible when it is being hit on the floor. However if the kids are playing with go li the size of golf balls, or they are really playing with golf balls, or crystal balls, or gorilla glass balls, then maybe the sound can be heard. Low frequency sound like foot stomping, hammer hitting or mallet pounding will create a low sounding noise and yes, they can be heard loudly. But marbles, they produce higher pitch noise which is difficult to transmit to the level below.

kids playing marble
kids playing go lis – Source:

Soapy Water Bubbles Bursting in Sanitary Pipes

Happens usually at night when it is the scariest, it is because the pipes are not used often. The sudden change of water flow mixed with soapy bubbles produces air pockets bursting and echoing through the pipes, making it sound like marble balls. This usually produces a single sound instead.

roof vents

roof vents – source:

Mosquito Trap Mechanism

Running water open and closes the mechanism and the repeated closing and opening of it produces marble dropping sound (!?)

mosquito trap

mosquito trap – Source:

Air-con Condensation

Condensed water dripping within the pipes causes the marble dropping sound. Could be due to the echo, due to the bouncing of the water inside the pipes and so many more reasons.

aircon condensation

aircon condensation – Source:

But nevertheless if there really are supernatural beings playing these marbles… then there must be a lot of them because it’s practically in every HDB flat and every level that we hear people talking about them.

Also, the population of Singapore is definitely lower in the past as compared to now, so how is it possible that the “previous population” be able to fill up so many units of HDBs to play the marbles?

And yes, there will be reasons that try to explain the supernaturals, like maybe they are able to replicate themselves etc..

So there you have it. The mystery of the marble dropping sounds explained. Or is it?

Do you hear that in the new HDB BTO flats? Let us know in the comments below!


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Mosh says:

Water hammering is a totally different issues. When water hammering occurs, the continuous sound of metal pipe / PVC vibration is intense. And it occurs mainly in the toilet or in the kitchen.

yishunstar says:

i live in yishun and my family and I used to hear these marbles dropping sounds too, for many years. its definitely the sound of marbles bouncing and i know what i heard. we have asked our neighbours ,both upstairs and downstairs , they heard it too and everybody thought it was the other party who has children playing marbles.

Anonymous says:

This is also known as water hammering, if I recall correctly.
Caused by change in pressure when too many people flush toilet at the same time. Water cannot fill up fast enough, and so get the popping sounds which sounds like marbles. Please read up on water cavitation if interested

Anonymous says:

Jinnies playing with marbles..

Anonymous says:

Me too…..I stay last floor,even day time also hear mistery sound.
12 yrs at Pasir Ris,now we family used to it.But we pry,azan radio,qomat and recite quran.Alhamdulillah geting better now.Must belive theres another dimension.They also mahlok Allah!

Anonymous says: