The Bristol hum has blighted sufferers in the city for decades - but what is behind the elusive buzzing noise? Hearing gone wrong or could sinister forces be to blame?
The hum is a phenomenon that has been reported in towns and cities across the world from Canada to New Zealand.
In Britain, the most famous example was the Bristol hum that made headlines in the late 1970s.
One newspaper asked readers in the city: "Have you heard the Hum?" - now we want to know if you can still hear it.
The problem has persisted for years with residents complaining of sleep loss and headaches with experts claiming traffic and factories were to blame.
But, according to the Low Frequency Noise Sufferers' Association the problem is on the increase with 2,000 people so far contacting its helpline.
It says it receives several new cases every week.
What could be behind the noise? Everything from gas pipes, power lines, mobile phone masts, wind farms, nuclear waste and even low-frequency submarine communications have been blamed.
Dr David Baguley, who's Head of Audiology at Addenbrooke's Hospital in Cambridge says over-sensitive hearing may be to blame.
"It becomes a vicious cycle," he explains. "The more people focus on the noise, the more anxious and fearful they get, the more the body responds by amplifying the sound, and that causes even more upset and distress."
I'd never heard of this till today, however I am relieved to realise that its not my tinititus that has got worse, which was my first assumption. I used to live in Horfield which was very quiet area and seemingly no noticeable 'HUM'. I moved to Bradley Stoke last year and noticed the 'HUM' on my first night there. I put it down to all sorts of things, but could never really put my finger on it! Alexis, Bradley Stoke
I have had this for years, lived in Yatton most of my life, but with 18 years in Sheffield/Doncaster (still heard it there), but have recently returned from two weeks in the Highlands of Scotland, noise free, now it's back with a vengance. Also there are times when one ear appears to be just muffled for a short period, although I did have more than 24 hours of this recently. Lyn, Yatton, North Somerset
The 'hum' is definitely AC mains noise from outside transformers. Some years ago I noticed a loud, low-frequency hum that only happened late at night, when all other sounds like traffic and birds had died away. It was so infuriating that I armed myself with a torch and I set out to find the culprit. The problem was that once outside, the 'hum' appears to be coming from all directions - you can't just go in the direction it sounds loudest - I guess this is something to do with the physics of low-frequency waves? But this does correlate to what other people have said above. Nick, Reading
I totally agree with everyone who has heard the hum. No one in my family can hear it but me. There appears to be a rhythm where the dull tones go up and down with gaps, yet constant. Great to hear there are other who can hear this annoying noise they have my sympathy! Diane, Derby
I am so pleased to read this story and the comments that go with it as I now know it is not just me. I have been very conscious of the hum since I moved into my flat in Redland in 2004. It's not always there but all the comments about an electric hum at night as you are about to sleep really resonate with me. Interestingly, I also live down the hill. I think the explanation of over-sensitive hearing can only go so far, because I don't hear it much elsewhere. Eric, Redland, Bristol
I was victim of so called Bristol HUM. At first I was unaware of it having a name and suffered sleepless nights being anxious as all i could hear was this low frequency noise, until my grandad told me it was a well known phenomenon. I looked into online to find it affected older people (i was 34 at the time), with good hearing but also deaf people. Likely to arise in buildings with several floors, especially with a basement, which all corresponded to my circumstances. I noticed it was especially strong on Sunday night around midnight and Saturday mornings before lunch. Oliver, Bristol
I had never heard of the Bristol Hum until today, but I'm also delighted to hear that it's not just me. We live right out in the quiet of the countryside and although the local farm sometimes has fans working in its chicken sheds at night, this doesn't always account for the sound I can hear in the early hours - a low frequency, barely audible sound that pitches higher then lower. Would it not be a good idea to map all of the 'hearings' to see whether or not there is some sort of pattern? Intriguing for sure. Sue, Worcester
I hear this all the time!!! I find that it gets louder at night and like so many others, no one else seems to hear anything. The local council actually did sound testing and couldn't hear anything. I am looking forward to the day that it is found out and stopped or I may just go crazy. I have tried noise cancelling headphones and they don't work for me. Amanda, Reading
As someone said above, I thought I was the only one. Interesting that here in South Wales we're not too far from Bristol. 'The Hum' began for me when I returned from holiday lasy summer. Lying in bed at home I heard what I assumed was a plane or helicopter in the night sky (it's a common event). However, after half an hour it was still there, not varying in volume or tone. It was there the next night, and the next... and there was nothing in the sky. It's not humming at the moment (went again a couple of weeks ago) but since last summer it's been constant almost every night. I don't hear it in the daytime or early morning - just late at night. John, Newport, South Wales
I could hear the Bristol Hum when I lived in Bedminster in South Bristol. It persisted for the entire 8 years I lived there. Now I live in East Bristol and haven't heard it since. It was a hideous high-pitched buzzing hum but only in evidence during the daytime, thankfully. I'm sure it was this little tiny electricity substation thingy just up the road - sounded like vibrating cables or something. Awful, really tinny and intrusive. It can't possibly be 'oversensitive hearing' or it would be surely in evidence all the time! Sounds like a lame excuse for not bothering to investigate to me. Steph, Bristol
Yep, I've heard this for years at night and I can't believe that my wife, lying next to me can't hear a thing when I tell her about it. Here it sounds to me as if there is a truck parked outside with its diesel engine idling, or that the washing machine is rumbling along downstairs. Nigel, Woodstock, Oxfordshire
I recently went to the doctor as I was getting stressed and anxious about sounds which I could hear but no one else could, but I could always prove that the sound did exist. My audiogram showed that I had extremely sensitive hearing. Being told this and discussing with my doctors strategies of how to solve it was a great help. Though getting help on the NHS was a nightmare as most doctors will simply ignore you as if you are wasting there time so I had to go private. Jay, Wiltshire
I have heard it, intermittently, all my life... always at night, when it is otherwise quiet, so more often in rural or suburban neighbourhoods. Happens about five or six times a year in the suburbs and maybe once a fortnight in a very quiet rural location, such as where I live now. David, Kingsbridge
Thank you BBC, and thank you everyone. I've been hearing this noise for 5 years or so, and in three different houses near the same area in east London. Drove me mad, as it pulsates as well as drones at night. It can be heard during the day but other noises block it out. I'm now learning to accept and it doesn't bother me as much but it's still auditable. It stops with ear plugs, but not with short term power cuts. I believe it its man made, and I believe it's related to water pipes and valves in properties. I changed all my water valves (water tank and toilets) and the noise stopped for a month. Then started again but at a lower pitch. Mr Patel, London
I experience this low level droning at one of my homes in Hampshire. I do not hear it at my other home in Bath. I would suspect that the cause - in at least some of the cases - is other people's music systems. Although the top notes cannot be heard, the base notes vibrate and this is what sufferers hear. I have come to this conclusion after staying in a block of flats where sound from home cinemas was a real problem. Margret, Hampshire
I used to hear a pulsating, low-frequency noise, like an electrical buzzing, when I lived in Luxulyan, a village on the edge of the clay country in Cornwall. It only became apparent under certain atmospheric conditions - damp, cool air and a low cloud base. We lived overlooking one end of a valley, and it was as if the clouds and valley were serving to channel and amplify whatever the sound was. It didn't ever seem to last very long, and was not always audible indoors, but it was very puzzling indeed. Ben, London
It is great that the LFN is being taking serious at last. I have had a lot of conversations with the County Council environmental agency and although understanding can not help me. I have also had a piece written in the local paper to highlight the problem and had lots of response from it. The best advice I can give for a good night sleep is to buy on Amazon a 'womb music for babies' on CD and have it on automatic playback at night, it masks the sound and works great. After months of not sleeping I am now getting a good night sleep. Joanne, St Asaph, North Wales
Hallelujah! I thought it was just me! When I lived in Woking, the noise was almost deafening at times. I went walking about for hours to find the source. Eventually driving for miles and turning the engine off. It sounds like a HGV idling its engine some streets away. Here in Edinburgh, there's more background noise, so not as noticeable, but if I listen out for it, it's still there... Alan, Edinburgh
I've been hearing the hum at night on and off for a few years. It's very different to tinnitus which is high-pitched and difficult to ignore. I don't have a problem with the humming sound, it doesn't disrupt my sleep much; the main problem is trying to convince my family that I really can hear something. I always assumed it was something to do with electricity/cabling - although a Dr Evil-style base deep underground sounds a lot more fun. Angie, Manchester
We have lost countless nights sleep due to a low frequency pulsing hum. Stroud Council kindly sent a noise engineer who pinpointed a low frequency noise, but at too few decibels to be an official nuisance. By chance we discovered that the council offices had a huge ventilation shaft pointing our way, and they put in a timer system so that their noise switches off during the night, which has been brilliant. However - to our embarrassment there is still a residual noise pulsing through the day and night which is tolerable most of the time, and playing a "waves" CD at night helps mask the noise. Thanks for all these comments, it is good to know we are not alone. David and Adrienne Rudd, Stroud
Thanks goodness for this thread! I thought I was the only one!! My hum is the same as Kathleen's - an undulating noise like a generator and I have tinnitus in both ears. I also occasionally hear it in other locations - but always only inside a building, not outside. I also hear it during the day as well as at night. David, London
I can't tell you how relieved I am that the BBC has raised this issue. I've been thinking I'm losing my mind since October last year when I started hearing a low humming sound. I'm convinced it's something in my neighbours' house and I've had environmental health investigate it and they say there's nothing I can do about. I'm due to go to for a hearing test next month to rule out tinnitus, just to convince the Council I'm not hearing things!! I'll certainly be bringing this article to their attention today. Norma, Dundee
I used to live in Bristol and I started hearing the hum in the 1970s. I continued to hear it up until I moved to Portishead in 2000. I always assumed it was tinnitus, but my husband says it is to do with the storm water tunnels that run under the city with water pumps running. When I moved to Portishead I stopped hearing it. Helen, Portishead
I suffer from high pitched tinnitus, so I know the difference between it and the 'hum' that we hear. The hum has a throbbing element to it. At first I thought that it may have come from machinery in the quarries, but was told they do not work at night and all machinery is closed down. We live among the Snowdonia mountains in the Nantlle Valley, so we thought it may come from the traffic on the new by-pass which was resounding among the hills. It is not a permanent phenomenon and is sporadic, so must be man made. Brian, Caernarfon
I have been hearing 'the hum' for about two years and find it distressing, especially as I live in one of the most peaceful areas of the country and one of the few locations where one can experience 'silence' unless of course you can hear the hum. It is worse in my home and at night although I have heard it in other settings. It is maddening as my husband and other people close to me can't hear it although one neighbour also suffers similarly. Faye, Richmond, North Yorkshire
For years now I have been aware of noise in the background. I always called it white noise. Since the introduction of mobiles and the increase in computer usage, for me it has got worse. The effects for me are things like, intense earache within seconds of using my mobile phone, so I never really use it. I can also tell if the person that I am speaking to on the phone, landline or mobile, has their computer switched on. The intensity of earache, and the time in which it comes increases if they are connected to internet. I find myself becoming scrambled, and another effect is excessive tiredness. Sahra, Taunton
I think it could be phase 3 electricity with a faulty switch. I think the cables go under my terraced house to a pottery at the rear. Does anyone else have a view on this? Pat, Barry, Vale of Glamorgan
I have had the hum on and off for years and have on many occasions opened windows and looked outside for a car running but have come to the conclusion that it must be some for of tinnitus. There is no logic to when I do or don't hear it but it seems to be mostly when I'm at home in bed. How nice to hear that it is not just me! Julian, Bournemouth
I have had this problem now for some time and noticed it first at night and found that my husband couldn't hear what I could. I went to see my GP and was referred to a specialist. The sound is a low droning noise, like an aircraft approaching from a distance. The specialist said it was tinnitus but that I also had exceptional hearing - in the top 10% of people so the theory that it could be something to do with the volume control in my brain being turned up too high, does make some sense. It only bothers me when it is very quiet and other sounds don't block it out. Linda, Farnborough
Thank goodness it's not just me! My wife and kids think I am mad. It is every now and then, a very low frequency hum mostly at night and I can 'feel' the sound in my ears. It is very oppressive. Andy, Burnham-on-Sea
I hear it off and on at night. I live close to the sea. Used to think it was the flour mill in Newhaven, or perhaps a tanker or large ship coming down the Forth. My husband doesn't hear it. I'm relieved to hear other people hear it - although in other locations! Jude, Edinburgh
Thank goodness it's not just us! I thought we were going mad. Ever since moving to our new house last year my wife and I have both been able to hear what we call "The Shipston Hum". She hears it more than me and some days it goes away completely. Originally I thought it was the wind blowing over the top of the chimney pots, then I thought it could be the sound of pumps echoing along the sewer pipes. Who knows? Edward, Shipston-on-Stour
For nearly 11 years I heard the 'hum' in Westbuty-on-Trym, north bristol. On some occasions nothing but at other times I found it very difficult to sleep. It did not affect my children. Three years ago I moved 'up the hill' overlooking the village of Westbury-on-Trym. I have not heard the hum at all. I can assure people it is incredibly irritating I am so glad I moved the mile out of the village! Jane, Bristol
Indeed! I have for the past decade or so started becoming aware of a constant noise in my ears, if I concentrate on it, almost like a high-pitched whispering buzz. It is not tinnitus, I am sure. It is however, very, very disturbing, and can threaten the sanity quite easily. I always ignore it and keep my mind occupied, because I would go bananas if I were to pay attention to it. Arun, London
Yes - there definitely is a hum! We hear it all through the night - have put it down to the Avonmouth Docks or perhaps the motorway? Don't believe the comment that it is because of sensitive hearing, or that the brain exaggerates - nonsense. This is certainly due to something physical. Maggie and Lee Bradley, Bristol
Yes! I hear 'the hum' even though my husband, whose hearing generally is better than mine (we have both had our hearing tested), cannot hear it. I also hear an almost constant 'hiss' which has been diagnosed as a kind of tinnitus, so I know the difference between internal and external noise and the 'the hum' is definitely external. I heard it as a child living in Bedminster, then didn't hear it when I lived on the outskirts - now I am back in Bedminster I hear it again - especially at night when other sounds are quieter. Sometimes it is louder than others and it can be quite maddening and stop me sleeping some nights. Lis, Bedminster, Bristol
I am fairly certain that the hum I hear, which as most people have said only occurs inside, is due to sewage and/or drainage and water pumps, which run at all times, just about everywhere! They are linked to buildings directly via pipework systems, so it is logical (in fact to be expected) that they will be heard even over long distances from the source. I am fairly sure this is the case, as I have only been aware of complete silence during major power-cuts, not during small localised cuts. It is an eerie sensation when that happens. Until we return to an age where gravity is used instead of electric pumping, this phenomenon will not improve. Mick, East Leake
I was very excited to hear that scientists had discovered what was behind the Bristol hum. I remember the news stories from years back and was fascinated by the phenomenon. How disappointing it is that scientists have once again put it down to over-sensitive-hearing. So, there remains to be no explanation for it. I can sympathize with the people who are affected by this - it must be so frustrating, and especially now that a new report suggests that victims of the hum are imagining it. In other words we haven't come any closer to discovering the answer to this mystery than we had in the seventies. Paul, Bath
My mother has complained of a humming noise for a long time and I am sorry to say I didn't take it seriously and thought she was hearing things. About two years ago my husband said he could hear a droning noise I couldn't hear it then. However he keep complaining about it and one morning I was lying in bed and I heard it. Now I hear it all the time. It is like a fridge motor running all the time and really irritating! Two of our neighbours that we have spoken to can hear it there may be more but people tend not to mention it for fear of not being taken seriously! The environmental people brought a meter and said there was low frequency noise and they would look into it. they said it might be coming from Wessex Water in the village. They also said they would put a meter in the house but that was back in January and we have not heard from them since. I don't think they think it a priority but it can be very distressing - especially at night. Alison, Saltford
I have the 'hum' Its in my head. Its like pressure, throbbing. Like a car engine being left on. All to do with tubes and sinuses. If I use headphones its worse. The 'hum' isn't outside my head. Doreen, Swindon
I can always hear a constant hum from where we live which is near the Avonmouth and Portbury docks. I have always put it down to the docks and the work which goes on there at night. I must admit I quite like to hear it on the few nights throughout the year when it is not there I have terrible trouble getting to sleep. Kim, Shirehampton, Bristol
I have certainly heard it in Burwell, a village just outside Cambridge. I am always amazed when I visit there that people can live with that continual deafening hum but it appears my friends don't hear it. It is quieter inside the house than out so it is definitely an external sound and yes there is a power station near by but whether it is that i couldn't say. Jayne, Cambridge
In some cases, the sources of these disturbances are obvious, like my neighbouring farm. They run a large pump overnight to irrigate their fields and this produces in me all the effects others describe: most stressfully, an inability to sleep through it. It's worse in the house as the low frequencies penetrate the house and bounce around off the walls: this is why many other correspondents report being only able to hear their hums inside - such noises may travel miles unnoticed outside. Neil, Blaxhall
Refrigerator / washing machine motor hum can come from neighbours' flats or houses. It is often transmitted through connecting concrete flooring. It can be eliminated by placing vibration absorbing matting between the machine and floor. Paul, Munich
I hear the hum a lot. Where I live, on the outskirts of Glasgow, it can be quite loud at times, but it often dies down at weekends. If there is a fall of snow it seems to go away altogether. It is nice to get out to the Highlands where I can get away from it. To me it is modulated harmonics of the AC mains. Outside the Partick Thistle's ground there is a transformer station which strongly resonates at these frequencies. When the Mugdock Reservoir improvements were going on, I could here the diesel generators which ran all the time. These were just one of many contributors to this sound that can travel significant distances. David, Glasgow
I experienced a low frequency hum in the Egham area which went on for many months. It was not noticeable during the day, probably due to the the noises of daily traffic etc masking it out. It was worse at night around midnight and the early hours. I believe its source was from the heavy electrical equipment at the nearby railway station but cannot confirm this. Good luck with trying to get an environmental health officer out at night! Because of its frequency it gave a surround sound and it was difficult to say where it was coming from. Robert, Egham
Thank you. I thought I was the only one who had this problem. I hear the noise all day and night but only in the house and I have previously blamed the freezer, the pipes and the neighbours. I have only been aware of the hum in my current house as in the last property I lived within a few feet of a main road so constant noise was a normal part of my life. My current solution is to place the dab radio near my bed, tune it to the Birdsong channel and play it throughout the night. This works quite well to drown out the hum and I can get a good night's sleep. Steve, Bedfordshire
I have suffered "The Hum" off and on for several years my husband cannot hear it and I thought I was going mad. I have kept a diary about the noise. I live out in the countryside no main road (private drive)no wind farms, or overhead power cables, the hum varies at times in noise level, and has reduced me to tears at times. If I leave the house and go several miles away I cannot hear it. Outside the house it is fainter, but still there. Perhaps now there will be people who believe me. Jenny, Aberdeenshire
For some time now, while trying to get to sleep I have been aware of a low frequency background sound in the bedroom, rather like the distant sound of a fridge running. I have tried, before going to bed, switching off the fridges, central heating and anything else in the house that could make a noise, but the sound remains unexplained, to this day. I live in a quiet, semi-rural suburb, where there is nothing outside which could generate such a background sound. It remains a puzzle... Dave, Winchester
I've been noticing a very low background hum when it's quiet in the house, and I thought it was perhaps the freezer or the electricity lines. But that theory was scotched when all our power was cut during a big storm, and the hum was still there! It's not maddening to me, just puzzling! Ann, France
I am male, 50, and have heard the "Hum" at night, on and off for many years. I used to get up and check all electrical items, then thought it might be work on the rail lines (about 1km away) some nights it only happens for a few minutes and others I cannot sleep all night. Nigel, Bournemouth
I've had this problem since about 1997. It came on suddenly one night, and I thought to myself, what on earth is that noise? A major nuisance at first, but I've got used to living with it. I believe it's my ears hearing the blood flow through my head. Like listening to a river. If earplugs don't block it out then, logically, it's an internal noise. Something your body is generating from within. Sufferers: Eventually you will get used to it and it won't be such a problem. Colin, London
I tried to locate a hum when I moved here. Eventually I realised that there is no one source, but an aggregation of many, which is why we don't find 'IT'. The 'many' are lorries cruising at the legal maximum on area roads, driven by motors with 4, 6 or 8 cylinders and all turning at speeds with common fundamental frequencies. Example: 4 cylinders cruising at 2000 rpm gives a frequency of 133 cycles per second. Simple summation plus selective amplification by household structures means that there is a pervasive but non specific background noise, since these frequencies carry more efficiently than higher ones do. Mike, Martock, Somerset
I moved to Bristol in 2003 from London. I moved to Cliftonwood in 2004 and after about a year I started to hear a droning deep humming noise. My wife heard it too and we contacted our neighbours and the local council. One of our neighbours heard the noise but the others didn't. I assumed it was the work on the harbour front and underground drilling for laying pipes. However, the droning would continue all night and our sleep was badly affected. I have since moved to Bath and the noise has gone. In my experience, I think the scientists have got it wrong as I never had a problem with my hearing in London or Bath! Tony, Bath
I have been hearing this hum for years, it usually happens in the middle of the night. I wake up and it is impossible to go back to sleep. I have no idea were it comes from but I do know it is not in my house, it is outside, and seems to come from a specific area, but I could be wrong because it seems to be everywhere. Pauline, Merseyside
I hear a hum all night. I live beside a electricity sub station- so I assume that is where it is coming from. It is there every night! Sometimes can become quite loud. Maggie, Aldershot
I asked my partner for the first time last week about this noise like a generator. It's an undulating noise. I am interested in this because I hear it whatever my location. I have had tinnitus for 25 years and its different - tinnitus is localised in my right ear, this is a sound like a vibration in my head. Kathleen, Gateshead
In hot dry weather, the overhead cables create an intolerable (to me) low hum. We tracked this around the north west, along all the roads where the cables are. At the worst spots, even my husband could hear the hum. At home, in the night, wrecked my sleep. Once the hot weather broke and the breeze got going, and showers, the hum stopped. This is a known phenomenon in Australia and the USA. Time to put those cables underground, say I, in the towns and villages. As it is, they are a nuisance anyway when there are gales as trees and flying branches can bring them down. Rose, Australia
Noise cancelling headphones for everyday use, or more elaborate and expensive, microphones and time delayed inverting amplifiers and loudspeakers in a bedroom, or other fixed head position locations; are they a possible solution? Jim, UK