More Information On Reducing Low-Frequency Home Noise and Vibration –

We received a question from a consumer regarding low-frequency home and vibration. After a response from expert staff of Acoustics and Noise instructors and a few additional posts on this general topic of interest, the response below came from the original consumer. Dear Sir, Here is my reply. You asked for it, and it is […]

We received a question from a consumer regarding low-frequency home and vibration. After a response from expert staff of Acoustics and Noise instructors and a few additional posts on this general topic of interest, the response below came from the original consumer.

Dear Sir,

Here is my reply. You asked for it, and it is lengthy. I am so grateful that you all are taking your time to give me your suggestions. I think a probable low frequency noise source, in addition to the trains, and obvious manufacturers’ noises, could be an asphalt batch plant that is located just behind our neighborhood. I drove by and listened and it is quite noisy with its clattering conveyer belts, giant blower, and the huge rotating mixing bin. I doubt we could have any influence on quieting such an operation. When we moved into our present house this plant was hidden by trees. Now that the leaves are gone, it is easily seen. Let the renter beware!

We have tried all the things that were suggested in your e-mail. White noise machines and fans just added noise to the home and was not the solution I needed. The best brand of ear plugs worked well, but are kind of dangerous when you need to listen to what is going on in the house at night….like when someone might be sick and need help. ( mothers can appreciate this reason), or a tornado siren, etc. My husband must sleep and so I have the “night watch”. .The Bose headphones (thanks Grandma) did not do a thing for the low frequency, but one of my sons is enjoying them tremendously now for listening to music. I hate that she wasted so much money on something that didn’t work. I, too, have wasted lots of money buying several bundles of Fibrex to use as “bass traps” of sorts thinking that it might help. It did not.

We did the realtor thing also. We moved from our first house recently. That house has its own story. We had moved to this town from out of state and did not know much about the area. Well, the house we bought was down the street from a gas well compressor. It was hidden in a wooded area and we did not know about it. Who would ever think that such a thing as a gas well compressor would be in a neighborhood…..only in Texas. The days we viewed the house happened to be some of the few days a year that the compressor was down for repairs or maintenance. On closing day when I walked up the stairs to turn the key in the door, I said to my self, “What is that noise.” After searching the neighborhood, we discovered the culprit to be a very old noisy natural gas driven compressor on a gas well. I fought that oil company for a long time and only was successful getting them to put up a wooden fence that did absolutely no good. Oil companies are King around here. They always expressed to me that they were compliant. They were, but this city has wimpy standards and codes that do not measure low frequency. We had spent lots of time, sweat, tears and money fixing up “this old house” and we did not want to move. We had redone the wooden floors ourselves, and I did not want to cover them up with carpet, even though that might have helped with the sound. We couldn’t afford to change out the old windows that were huge and had just been refurbished by me. Our home was built in an L shape facing the compressor. This was perfect for capturing the “waves”. They came right in through our large glass windows. In addition to that, there were metal awnings over each window acting like ears to reflect the sound in through the single pane windows. (I had refurbished those as well) The neighborhood was refreshingly quiet on the few days that “The Beast” was off for one reason or another.

After three years of torment, the for sale sign went up. We disclosed the noise ( which probably brought our home value down) to the new buyer. She was not home much of the time anyway so she was not as bothered by it. The search for a quieter place was on. We were scared to think of buying again without knowing if “the sound” would be in that area too. , “ I had gone to look at houses for sale, just to see if I could hear how the house “sounded” and just to “test” a neighborhood. We decided just to rent. Little did we know that rental homes that are large enough for our family of six and that are in our price range are extremely hard to find in our town. We ended up having to grab a house when it became available just to get a decent place to live. As it turns out, we ended up moving from one frying pan to another frying pan so to speak. We have now been living in this rental for ten months and we are still plagued with noise problems. I say we because even though the others of our household are not as sensitive to LFN as I am, they still have to live with someone (the mom) who is and whose daily life is not as efficient as it could be were I able to sufficiently rest and relax. I went with our church on a mission trip to Mexico a couple of years ago. While up in a quiet mountain village, I discovered how wonderful peace and quiet were, and I realized just how much that LFN affected me while living in our bombarded home.

Since we now rent, I can’t beef up the windows, but I have heard that double panes do not help with low frequency anyway. I’ll try to make a window plug to see if that helps. I can’t run the TV “off channel” because we need to concentrate and study at home. We are one of those homeschooling families. Also, that noise is annoying to my teenage daughter and me.

You asked about whether or not other neighbors have had the same problems as I. I can’t tell you that. We haven’t gotten to know our neighbors very well yet. There are some factors to remember when questioning the neighbors about noise problems. Many in our neighborhood are retired and wearing hearing aids. They, of course, do not have problems with the noise. Second, if they did hear the offending frequency, they would be hesitant to say so in fear that this information might be something that could “go public” and cause their home values to go down. Third, low frequency noise is most often a source of annoyance to those fifty and older (I give away my age). The younger ones in the neighborhood have not yet reached that point. On a side note, there is an old man in the neighborhood who sits out in his attached garage with the garage door up for many hours a day. He will even sit out there when it is 100 degrees outside. I am just curious if he has a problem with LFN and is trying to escape it as I am. By the way, when I am out working in my ten by twelve foot shed (made of that composite siding stuff and sitting on wooden skids) I can’t hear or feel the vibration. This makes me wonder if the noise could be possibly ground borne. The LFN does seem to be worse when it is raining…..hum….saturated soil conducts noise very well doesn’t it. If the LFN was ground borne, would ….putting down a wood or laminate flooring that had a good coating of Green Glue behind it help. Is there any conclusive way to determine if LFN is indeed coming through a concrete slab? (I know this is some of that thousands of dollars of advice coming my way.) As was suggested, I am going to try to decouple the bed from the floor. I’ll order some sheets of sorbothane for that purpose. They are supposed to work better than rubber. What kind of instrument would measure the wall or slab vibrations?

My son, who is now an engineering major (ME), once measured the sound with a microphone on his computer. Using music recording software, he measured the frequencies from 30 to 60htz or so. He had fun isolating the sound and turning it way up for all to hear and feel till we yelled at him to shut it off….ah teens. He captured it in the tile shower. So I know it is “out there” and not just “in my head”. It could be that I am one of those “hummers”. Read about them online. They can hear the Kokomo Hum, the Taos Hum, the London Hum, etc. There is even a low frequency sufferer’s society. This is your market for whoever invents a comfortable low frequency blocking head gear that can be worn at night. This wouldn’t block (as ear plugs do) the types of noise that parent’s need to hear at night.

I would be interested in any tests like the one that one of the teacher’s mentioned ….measuring the frequency outdoors and comparing it to the indoor reading. I guess I just have to rent a device that measures what I need to measure. We would like to move, but as I said previously, I would not like to buy a home without knowing that I can block the offending noise that this town seems to produce whether from trains, underground gas pipes, well drilling, or chemical and manufacturing industries, etc. If we were to rent, we could not spend lots of money to “treat” the house for LFN. My husband likes his job and would like to stay in the area if possible. Me, I’d rather move to a small mountain village in Mexico. Or until then, I’ll just sleep with a pair of sorbothane shoe insoles smashed over my ears.

I am glad you are teaching classes to train engineers in ways of mitigating noise and vibration, because ultimately these problems have a personal side and a personal face. If I have been a “textbook” case for you then so be it, and may you all become the best problem solvers in this area. If any of you have any other suggestions for me, send them my way. If you solve my problem, then my hat is (or should I say ear plugs are) off to you. Please do not share my e-mail address with the masses.

My humble thanks,

C

3 thoughts on “More Information On Reducing Low-Frequency Home Noise and Vibration –

  1. Dear C

    I read your harrowing tale with much interest as I too suffer from LFN (low frequency noise) at night time. It is produced by a nearby landfill gas to energy facility here in the UK. In our case I can hear it but my wife cannot. Nor can other visitors we have had staying over. The noise survey carried out on behalf of the company that runs the plant indicates that it is compliant with the regulations but the regulations are hopelessly inappropriate for such an application. As for attenuating the noise level of LFN there is nothing you can do; it will come through walls as well as windows so double glazing has no effect. In fact, if anything it makes the situation worse because it attenuates the mid and high frequency noises (to varying degrees) which has the effect of making the LFN more noticeable. Masking it is often the only solution if it is very discontinuous. If it is more continuous – a kind of hum – I find that if I broadcast a 100Hz pure sinusoidal tone (that is less unpleasant than the LFN pure tone) it will often serve to destabilise the resonant standing wave that the nuisance noise sets up in my house – the hum – and which makes it so unpleasant. (If you assume the noise is airborne – which it probably is – and you go outside you notice that even when it is quiet you can hear no or very little LFN. And yet it is there. It must be there to be able to create the noise in the house. In effect the house acts as a low-pass filter allowing the LFN, mainly, to get in whilst the higher, frequencies which serve to mask the LFN, especially during the daytime are attenuated. And then when the LFN sets up the resonant standing wave it amplifies the noise level considerably. So if you can destabilise this wave with another wave you broadcast yourself it can be very beneficial. I downloaded a 30-second clip of 100Hz sinusoidal tone and using software called Wavepad I copied and pasted the clip till I had a 30 minute clip. I then transferred this to my Nanopod and created an “album” of 16 tracks (8 hours total running time) which I play through some smallish PC speakers. And for the most part, when the noise is a hum it works quite well. I certainly would have had to sleep elsewhere without it. Like you I have tried headphones – I even invested 120 dollars in some fancy Sony “Noise Canceling” headphones – but they achieved nothing and were no better than a pair of passive headphones. And your comments about discussing it with the neighbours are very perceptive; none of our neighbours have heard the noise either and you get the impression that they don’t really want to know. It’s a very divisive experience in all sorts of ways and has certainly caused my relationship with my wife to deteriorate as a result of my waking her up in the middle of the night on the really bad nights as I wander around the house, mattress under my arm trying to find a location where it is tolerable. Last night I slept in the conservatory. Again.

    So I don’t know if any of this helps. But sometimes I find that such experiences as this, which can be very isolating (are you sure it’s not in your head? they ask, again) can be rendered just a little more tolerable by the fact that you know you are not alone in your suffering.

    Good luck C, may you soon find the peace you are looking for.

    David
    Bedfordshire
    England

  2. I am an environmental scientist, and have been involved in the wind energy industry where this is also an issue. The problem is uncommon, with less than 1% of the general population able to detect LFS (Low Freq sound – less than 20 Hz) dominated by people over the age of 50, and two thirds are women. So you are not imagining the issue, but keep in mind that it is unlikely that it is your ears that are detecting the sound, and that LFS behaves very differently than audible sound does.

    I find your solution to be very innovative, and supported by some excellent work by a retired Univeristy Prof (Dr Barnes) in London, England. He obtained a microphone and laptop datalogger and wandered the city obtaining background readings. One of his more interesting observations was that background LFS declined after heavy trucks passed when near high traffic roads. This suggests that LFS can be neutralized by other LFS sound.

    I am no sound expert, but this is the only solution I have ever read about. It is basically the “white noise” approach used for audible sound, but in that case the goal is to increase the individuals toleration for the sound (which is how white noise works, by raising our detection threshold) but rather to distrupt and decrease the level of LFS inside your house, by increasing the levels of LFS generated inside the house.

    I know this sounds a bit out there, but read a few of the other accounts given on this page, for example the one where the hum returned after a new water heater was installed. The owner blamed the new water heater as the source, but it may very well have been that the old heater was “noisy” enough to have created the interference with the LFS. Getting the new heater to run better would of course just make the problem worse.

    So I put this idea out there. If you can generate a background inaudible “sound” of less than 20 Hz inside your house, using the technique described above, and play it over and over, it could disrupt the LFS being generated by the house. This could require a specialized “woofer” type of a speaker.

    If anyone tries this, I would be very interested in the result.

    Good Luck
    Don

  3. It’s me again, the one who wrote the “harrowing tale”.
    Thank you for your suggestions. I finally bought some sorbothane sheets from McMaster Carr. # 8514K62 . These were 12 by 12 inch sheets that were 3/16 inches thick. I bought the 30 durometer softness because the salesman said that the softer the sorbothane, the lower the frequency that was blocked.
    I cut four large circles out of the square. I doubled them up and placed two each in a pillowcase. I center one ear on one set of circles on top of my pillow, and I place the other set on my other ear being careful to cup my hand over it so my fingers and thumb are pressing around my ear. This “seals” my ear from the vibration. This is the most relief that I have been able to find. The sorbothane sheets in this thickness and size were $25 dollars a sheet plus shipping. I am very happy with the results and I now have a way that I can fall asleep at night or in the middle of the night if I am awakened. It is not a permanent solution, but at least I am thankful that I have some “escape”. We need to spread the work that there is this helpful product out there. I also bought a wrestler’s ear protection head gear. The circles of sorbothane can fit inside it so that I may wear it around during the day if I want. It is pretty funny looking, I’ll agree, but more importantly, it’s effective. I just tell any one who asks, ” I ‘ wrestle’ with a low frequency noise problem.” ha ha. Yours truly, C

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