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Open - The Singapore Marble Dropping Mystery
Written by Webmaster   
Monday, 10 September 2007 11:49



The Marbles Dropping Mystery has plagued many HDB flats residents for as long as anyone can remember. Ask anyone on the streets, chances are that 1 out of 5 would tell you that they do recall hearing those marbles dropping on the floor from the units above them, most of the time during unearthly hours, and sometimes, during the day as well. Often the marbles dropping sounds could be attributed to real playful children playing with marbles. 

But the concept of playing with marbles doesn't tie in well with modern times when marbles playing is already considered a traditional game. Besides, marbles are considered small objects and could be easily swallowed by young kids playing with them.

So, could the sounds of marbles dropping on the floor be due to playful children, or are they something else altogether? 


Children playing with marbles


Children playing with marbles in the old days 

 Though the Marble Dropping Phenomena was considered widespread, no one really dared to talk or even admit publicly that he or she had such a problem. Until 1 day.. someone wrote in to the Straits Times Forum...... 

The 1st Article in STRAITS TIMES - A letter to ST Forum
The date, June 6, 2005. 

The date, June 6, 2005. 

A Singaporean by the name of Joseph Wong wrote in to the Forum page of the Straits Times, complaining of marble dropping sounds coming from the above floor unit occurring in the early hours of the morning.
This is what Mr Joseph wrote:

I can hear marbles... or am I losing mine?
IN THE 15 years I lived in my three-room HDB flat in Lorong Ah Soo, my family had to endure what sounded like marbles being dropped on the floor of the unit above mine. Strangely, this seemed to take place only at night, at times in the wee hours of the morning. Never one for confrontation, I did not speak to the occupants upstairs, and we lived with it.

We moved to Punggol 21 five years ago, and the sound of marbles dropping in the wee hours of the morning seems to have followed us. I once trotted upstairs to see what sort of neighbours I have and the occupants were an elderly woman, her weak elderly husband and their domestic help. It is unlikely they played with marbles, and certainly not in the wee hours of the morning.

From conversations with friends, I was astounded to learn that this sound of dropping marbles is a widespread phenomenon in Singapore. It seems it happens only in HDB flats. One of my friends even suggested it may be the way HDB flats are built.

As a non-believer in the supernatural, I am eager to understand this mystery that is fast becoming an urban legend. I may have a legitimate reason to ask the HDB to explain it, since it seems to inflict only flats built by it.

Joseph Wong Yong Lye

Charles Goh: So it would seemed that Mr Joseph has wrote a  very interesting case. He had been experiencing marble dropping sounds in Lor Ah Soo for 15 years, and even when h has moved to Ponggul 21 5 years ago, the marble dropping sounds followed him there. More interesting was the fact that Mr Joseph had went up to the upper floor and found no children there, just elderly folks.
He has asked the HDB to give an explanation for the strange noise. Would HDB reply? It would certainly be interesting to hear what they had to say.

2 days later, Mr Joseph got a very interesting reply not from the HDB, but from another HDB dweller, a Mdm Sharini. 


The 2nd Article in STRAITS TIMES - The 1st Forum Exchange
The date, June 8, 2005. 

'Marbles' on the brain? Take them in the right spirit
I AM amused at the prospect of a reply from the HDB to the query by Mr Joseph Wong Yong Lye about the sound of marbles on the floor of the unit above his in the wee hours of the morning ('I can hear marbles... or am I losing mine?'; ST, June 6).

Having lived in four different HDB flats from my childhood to my present nesting ground, the familiar sound of marbles has become integral to my idea of HDB living. Amid all sorts of sounds, pleasant or otherwise, my reaction has progressed from being spooked, irritated and curious to mostly nonchalant now.

Until a better explanation can be found, my only explanation of the sound of marbles on the floor of the unit above mine is that certain jinn, or creatures from the other dimension, are fond of making such noises in the wee hours of the morning. Especially after all the neighbours above my unit have moved out! This was the case when my family was among the last few left behind in our block which was affected by the Selective En-bloc Redevelopment Scheme.

In the present situation, I unashamedly advocate that we stretch our neighbourly tolerance a little further, possibly to accommodate the ever-crowding supernatural world as we would our own fast-expanding one. I am, however, against any get-to-know-your-jinn-neighbour campaign!
If it is any relief to Mr Wong, I no longer hear the 'marbles', though my eldest son has described them exactly as Mr Wong did.

Sharini Shamsuddin (Mdm)

Charles Goh: So Mdm Sharini declared here that marble dropping sounds is very common & was an integral part of her life. She then advised Mr Joseph to take the marble sounds' in the right spirit!"

So should we embrace the supernatural world as she hoped Mr Joseph would do. So what IS HDB reply to this too?

But alas, HDB was spared from answering directly to both Mr Jpseph & Mdm Sharini through the intervention of a Ms Sujatha, who apparently had a very normal reason for the noise upstairs.  


The 3rd Article in STRAITS TIMES - The Second Forum Exchange
The date, June 12, 2005. 

No way to end the noise
I REFER to Mr Joseph Wong Yong Lye's letter, 'I can hear marbles... or am I losing mine?' (ST, June 6).

Over the past couple of months, I have been tormented by noisy children above me stomping their feet, running, throwing toys on the floor, dragging furniture, dropping heavy objects and so on.
I have asked the HDB on several occasions to advise the tenants on the upper floor to minimise the noise, but it just got worse.

HDB then passed the issue to the police for intervention and mediation, but that also ended in a deadlock, this time worse than before.

From the police, it went on to the Central Mediation Centre under the Ministry of Law. The matter is still pending.

I would like the HDB to explain how far its powers extend in situations like this.

I was told there is no clause in the Housing Act which gives it the power to penalise inconsiderate tenants.

It acts only when premises are being used as a gaming house, prostitutes' den or for other money-making activities. Eviction is enforced only on such grounds.

Can HDB amend the Act to give it the authority to enforce some kind of penalty and minimise the rigmarole of going through a gruelling series of investigations and fruitless meetings?

Sujatha Ommini Vidyadharan (Ms)

Charles Goh: Ms Sujatha noisy upstairs neighbor was real, with the HDB, Police & a Mediation Centre called in to boot. The issue of ghostly HDB tenants playing with marbles has effectiveky been 'replaced' by a real noisy neighbor problem.

Now, on safe grounds again, or maybe it was just sheer coincidence, the HDB, AND THE POLICE, now replied. Not to the 1st two forum writers though, but to Ms Sujatha only.  


The 4th Article in STRAITS TIMES  - The Government Replies
The date, June 18, 2005.

Noisy neighbours? HDB for mediation
I REFER to the letter, 'No way to end the noise' by Ms Sujatha Ommini Vidyadharan (The Sunday Times, June 12).

When the HDB receives feedback on noise nuisance, its officers will visit the affected parties. Where necessary, we also interview other residents nearby to verify the complaint.

We emphasise resolution through mediation. We encourage the parties to exercise consideration by generating less noise and also showing some degree of tolerance towards their neighbours for a harmonious living environment. We do not take sides in any neighbour disputes.

The police may intervene in cases of noisy neighbour disputes. However, most noise nuisance cases are community and neighbourliness issues that can be resolved amicably, if both parties are willing to communicate.

In private disputes, owners have to take responsibility to resolve such matters themselves. If this fails, the parties can seek mediation at a community mediation centre. In extreme cases, the aggrieved party may wish to consult his solicitor.

In Ms Vidyadharan's case, the HDB advised her upper-floor neighbour to avoid creating excessive noise, especially at night. Her neighbour has assured us they will minimise the noise created by their children. The police, together with the local grassroots leaders, also intervened to get both parties to talk. The matter has since been referred to the Central Community Mediation Centre and we understand both parties have met for mediation.

For feedback on noise nuisance, residents can contact our branch office service line on 1800-2255432 during office hours. Our HDB branch office will look into the feedback and give necessary assistance where appropriate.

The police recognise that noise pollution at night is likely to cause greater annoyance. As such, for noise pollution complaints at night (typically between 10.30pm and 7am), police officers will attend the scene.

ASP Victor Keong
Assistant Director, Media Relations
Public Affairs Department
Police Headquarters

Tay Boon Sun
Senior Public Relations Officer
Corporate Development Department
Housing and Development Board

Charles Goh: Thus for both the HDB & Police, they would be most happy to consider this case closed. Would then Singaporean be depraved of this chance to explore this mystery further?
Lucky for us, The Sleuthing Reporters from Straits Times are not lazing around & they recognized an opportunity to make news when they see one.

On June 12th, ST published an article regarding the elusive marbles, having consulted HDB and Industry Experts on this matter. Yours truly was 1 of them. 


The 5th Article in STRAITS TIMES - The Straits Times' Answer
The date, June 12, 2005

Mystery of the falling marbles
Structural engineers say noise comes from plumbing or concrete floors while others give different explanations
By Chua Kong Ho

HEAR that? Someone in the flat above is playing with marbles. But it's 1.30am. No child would be up at this witching hour.

The mystery deepens for bank executive Joseph Wong, 47, because his upstairs neighbours are an elderly couple. No youngster live in their five-room HDB flat. (Our 1st Forum Exchange)

When The Sunday Times interviewed the families living up to three floors above him, all denied dropping marbles or any other objects on the floor so late at night.

Also, the sound seemed to have followed Mr Wong from Lorong Ah Soo to his new home in Edgefield Plains in Punggol.

Wags, of course, would say he has lost his marbles.

But his letter to The Straits Times Forum Page last week, asking the HDB for answers, has stirred out of the shadows many who have been similarly vexed, if not puzzled.

It has also plunged Singaporeans into a frenzy of fuzzy theories. The Straits Times received more than a dozen letters, including one from Madam Sharini Shamsuddin, who playfully suggested that spirits are at work.

Internet forums are swelling with explanations that make you want to throw up your hands in disbelief. One that probably coaxed many laughs, both nervous and mocking, is the suggestion that the HDB had placed marbles between floors so that playful spirits would be so distracted playing with them, residents will be left in peace.

If so, private developers have been equally diabolical. Expatriate Julian Cohen, 42, has been haunted by the same sounds at each of the three private condominiums he moved into in the past 10 years. He also heard them when he was working in Hong Kong.

He said wryly: 'I guess Joseph can take consolation that the marble-dropper doesn't just live above his HDB flat but drives round to his second apartment above mine to continue his marble-dropping activities after he has woken Joseph up.'

Mr Wong's wife Geralda and six-year-old daughter Amanda, however, are sound sleepers, deaf to the disturbing noise. 'Always, the noise happens between 1.30am and 4am. It spooked me initially but as the years go by, you get used to it,' he said.

Postgraduate student Lim Leng Hiong, 28, who lives in Holland Drive, suspects golf enthusiasts are practising their putting at home.

In an experiment, he found that glass marbles, ping pong balls and golf balls, when dropped, produce different sounds. 'But it's hard to tell the difference when heard on their own,' he noted.

The only problem with his explanation, of course, is that HDB dwellers have been hearing the sounds of marbles way before the recent golf craze.

HDB would have you believe that every sound has a reason. It said in a letter to The Straits Times: 'To date, we have not received any feedback on the sound of dropping marbles where there has not been any attributable cause.'

What could be some of the attributable causes? HDB spokesman Tay Boon Sun is not telling. But he gave the assurance that the acoustic properties of flats do not differ from other residential buildings.

More forthcoming are structural engineers and the Founder of Asia Paranormal Investigators, Mr Charles Goh. Their answers, however, indicate that when things go bump in the night, the reasons are rarely beyond the mundane.

Mr Goh, 37, said the marble sounds can be traced to air-con pipes or old refrigerators, while the sounds of furniture being dragged across the ceiling, another common occurrence, could be due to lift doors opening and closing.

Structural engineers point to two probable causes: the plumbing and the concrete walls and floors.

Mr Wong subscribes to the last because that's where he hears the marble sounds in his flat.

Mr Crispin Casimir, owner of CC Building Surveyors, and Dr Tan Guan, a director at TY Lin SEA, will have you focus on the concrete.

Concrete floors may contract at night, giving off creaking sounds, Dr Tan said.

Mr Casimir added: 'Sounds travel and are distorted as they pass through concrete walls and floors.'

Mr Shek Kam Chew, 68, a structural engineer since 1966, is convinced it's in the plumbing.

'It's definitely not supernatural but what is called 'water hammer',' he said.

Water hammer occurs when water flow is shut off suddenly like when the toilet is flushed. This change in pressure rattles the piping and create 'clanging'sounds, which may sound like marbles dropping after distortion through concrete walls, he said.

Still sceptical? Why not stick with the obvious? Surveys have shown that Singaporeans sleep late. So really, it's just children playing with marbles.

Three explanations
1) When water flow is shut off suddenly, the change in pressure rattles the pipes, which may sound like marbles dropping after distortion through walls.

2) Some pre-fabricated floors used in HDB flats have an embedded high-strength steel cable which can give off creaking sounds when they contract.

3) It is really children playing with marbles

What the 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.'

What the readers say

'The pipes of some air-con units make popping sounds. These sounds resemble marbles dropping when they travel through the pipe embedded in walls. Another possibility is that in some old fridges, the compressor makes this noise which can be heard clearly only at wee hours when it's quiet.'
-- MR CHARLES GOH, Founder of the Asia Paranormal Investigators

'I'm quite sure that this 'urban legend' is due to a real social phenomenon: the Singaporeans' love of mahjong.'

'Could the sound be attributed to the expansion of a certain type of tiled floor in the much cooler early hours of the morning?'

Charles Goh: Finally the marble dropping phenomena reached its climax when the Straits Times published an article citing the results of an investigation by a paranormal group, SPI, on June 26th.    


The 6th Article in STRAITS TIMES - The Answer?
The date, June 26, 2005

Strange sounds due to water in PVC pipes
Paranormal investigators' society comes up with explanation for sound of falling marbles with an experiment
By By Goh Wen Zhong

F YOU'RE still hearing the sound of falling marbles in your flat, it could be your neighbour washing up at the sink.

After a five-hour experiment on Wednesday, members of the Singapore Paranormal Investigators (SPI), a society made up of paranormal enthusiasts, have come up with what it thinks is the real reason.

They say the sound comes from water trickling through PVC pipes, which gets distorted through concrete before emerging as the sound of falling marbles.

This phenomenon has been in the news lately.

It all started when The Straits Times Forum published a letter by bank executive Joseph Wong, who kept hearing the sound of falling marbles in his flat. A flurry of letters from other people followed, all saying they had also heard the sounds, and wanting to know the cause.

Some even suggested there might be a supernatural explanation.

But in a Sunday Times report on June 12, building experts said it might be caused by the rattling of water pipes when there's a change in water pressure, the contraction of high-strength steel cables embedded in pre-fabricated floors, or children actually playing with marbles.

The SPI was not satisfied. It wanted to narrow down the possible causes.

Said the society's treasurer, Mr Eugene Toh, 26, an insurance agent: 'We want to allay the concerns of the public with conclusive and reliable evidence to point out the cause.'

The society's month-long investigations hit paydirt on Wednesday when four of its members gathered at Mr Toh's home, an HDB maisonette in Bedok.

On the upper floor of the two-storey house, they dropped marbles big and small, flushed toilets, turned on taps and recorded the sounds.

They also recorded the sounds from the floor below.

They then compared the sound frequencies with a recording they had made of falling marbles.

SPI president Kenny Fong, 36, an assistant professor at the University of Macau, said: 'The frequency signatures of sound flowing from the sink through water pipes and that of falling marbles were almost identical.'

Asked about SPI's findings, Mr Shek Kam Chew, 68, who has 39 years of experience as a structural engineer, agreed that it was plausible.

For the SPI, which was registered as a society last month, the investigations do not end here. Mr Fong and his team want to do more tests to bolster their claim.

Charles Goh: So, could the sounds of falling marbles be due to water rushing down the sink? SPI thinks so & their investigation augment that argument.

But I beg to differ in my opinion.  Because if that would be true, then the marble dropping phenomena would have been more widespread than it is now, with multiple 'sightings' everyday.

Having lived in high rise apartments all my life, working in the building & construction industry for the past 16 years, and being an Investigators of sorts for the last 5 years. I am sure that the answers lies very simply before us. 

No scientific equipment or 'ghost hunting' gadgets is needed to unravel this mystery. Just plain common sense and some rational analyzing.  


The 7th Article NOT in STRAITS TIMES, but published here in API
The date, January 3, 2006

Marble Dropping is no Mystery
There is no SINGLE answer to this marble dropping mystery. Simple reason being the cases of marbles dropping sounds being heard should be examined 1 at a time.

No equipment is necessary. All it takes is critical & rational analysis of each case.

There are many plausible explanations, and each incident should be investigated based on its own merit.

Firstly we will need to realize that all kinds of piping run within the floor slabs and walls of a high-rise building.  These include our sanitary or soil pipes (you know... the ones which carries our waste.. erks!), water pipes supplying our PUB drinking water, refrigeration pipes from Chillers, water condensation pipes from our air conditioning. All these pipes have the potential of causing marble-like dropping sounds in our high-rise flats.

Poorly maintained or serviced equipment too can use marbles dropping sounds when they are turned on.

Therefore, the explanations would generally fall along the following lines.

(1) There are really children playing with marbles. - This is the simplest of explanation. Just go upstairs & check it out. Marbles sounds by children playing usually sound like many marbles are thrown onto the floor, and the sounds are frequent and inconsistent. 

(2)  Water hammering in PUB water supply pipes caused by prolonged period of no water activity in the water pipes. This causes air volume/pressure to built up in the pipe. When water is re-introduced into the piping system, pockets of air bubbles are formed as the water rushes in to replace the air. If you recall at times when you open the tap, and sometimes the 1st few gush of water is intermittent with air spurting out. Such gushes of water with air trapped within its flow will cause the water hammering sounds, which may travel through the concrete surfaces and appears like marbles dropping sounds. This kind of marble sounds appears only briefly and is seldom repeated for the rest of the night.

(3) Soapy water bubbles bursting in sanitary pipes. This usually occurs at night when the pipes are not so often used, and there is a sudden release of soapy water flowing down the pipes. This usually occurs when the higher floor units flushes down sufficient quantity of soap water. A similar bubbly situation would also occur when are already plenty of soapy water at the base of the piping system due to many residents bathing at the same time.  Each sanitary pipe stack has vents at the roof top to allow air to escape out. Thus the agitation of the soapy solution will cause bubbles to form and the resulting air pockets bursting will sound like "Pock! Pock! Pock!" echoing in the pipes, sounding like marbles as the bubbles 'break' on the surface of the water. Usually marbles sounds of this sort will be only singular sound of 1 marble (means only sound like 1 marble dropping) is heard.

(4) Aircon refrigeration pipes & old fridges piping after a period of time, will start to accumulate particulates and bubbles in its piping system.  and all these impurities will cause rattling and vibrations in the piping. Such sounds can manifest itself as marble dropping noises. That is why aircon serviceman would want to have 'Total Flushing System of your aircon after a period of use. Such sounds are faint, and often continuous. The sounds also appear when the old aircon or compressor unit is turned on.

(5) Aircon condensation pipes can also contribute to the marble dropping phenomena. When air-conditioning units operates, water condensation takes place, and are discharged via a small water pipe that will terminate into a sanitary pipe. Sometimes sediments or debris within the sanitary pipe will cause more water to be stored at the pipe elbow. Thus the water droplets that drip from the condensation pipe that is not flushed with the drainpipe wall will fall 'plock plock' onto the small 'water pool' inside the pipe elbow, causing the infamous marble dropping sound.

(6) Many of the floor traps are fitted with mosquito trap mechanism. This mechanism would be opened by running water, and closed when the water has ceased running. Thus a constant flow of water will caus ethe mechanism to open and shut continuously, and the sounds emitted will sounds very identical to the marble dropping sounds. 

(7) The sounds may not be marble dropping sounds at all. Our high-rise apartments have many equipments like water tanks, lifts, motor rooms, switch rooms etc. Condominiums would have even more facilities like swimming pools, tennis courts, artificial waterfalls etc. All these basically means there are alot more equipment & embedded wall piping running in our walls & ceiling. These also means alot more chance for vibrations caused by running engines, motors, turbines etc. All these vibration causing equipment has the potential of creating rattling sounds in walls and ceilings when they are start up. These rattling sounds can sometimes travel from 1 block to the next, or from the ground floor to the top floor, becoming more 'echo-y' along the way, till it manifest itself as 'marble dropping' sounds at the higher floor. These kind of marble sounds usually sounds mechanical, last for a period of time, and is constant during the period the sound is heard.

Last Updated on Thursday, 14 October 2010 13:53