Loading ...
Sorry, an error occurred while loading the content.

Re: HUM_FORUM: A way to locate source of low-frequency noise

Expand Messages
  • Copsne
    Thats what common sense would think, including me in the beginning. Acoustic tools will tell the tale thou. Like flying a plane on instruments, trust them in
    Message 1 of 12 , Mar 8, 2013
    • 0 Attachment
      Thats what common sense would think, including me in the beginning. Acoustic tools will tell the tale thou. Like flying a plane on instruments, trust them in the fog. 

      Outside are a vast spectrum of freqs below 50 hz. No sensed hum or vibration. Go into a structure and reasonance kicks the hum in. A parked, quiet car does the same. 

      Check out articles on sound propagation from tunnels. Same phenomea that is studied and accepted, and can be applied here. A long planar diatributor acts different than a point source. Geometrically it attenuates less than a point source. Couple with Long LF sound waves known as Rayleigh interface waves and theres the part of the story to travel of the sound waves that induce hum

      Testing to find the epicenter takes a long day and a good distance off the suspect line taking measures, collecting data. My results here, always have the lines as the epicenter. 

      Not saying its the only source, but here, it is. 
      Steve

      Sent from Steve's iPhone and I appologize for typo's

      On Mar 8, 2013, at 4:43 PM, "technicanalyst" <mr.steven.brown@...> wrote:

       

      Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?

    • marygaylor168@btinternet.com
      Hi, Reading your post, I say you know exactly what is, I would say, a major cause of the HUM...my home has been bombarded for the past three years, and to cut
      Message 2 of 12 , Mar 9, 2013
      • 0 Attachment
        Hi, Reading your post, I say you know exactly what is, I would say, a major cause of the HUM...my home has been bombarded for the past three years, and to cut a very long story short, I have been in touch with the company responsible...who asked me what I wanted them to do. Can I ask do you know what can be done to a property, some sort of insulation or attenuators. I would like to go back to them with a plan....because although they appear to have tried, they can't stop it affecting my home. Any advice would be very welcome.


        --- In humforum@yahoogroups.com, Copsne <c_o_p_s_ne@...> wrote:
        >
        > Thats what common sense would think, including me in the beginning. Acoustic tools will tell the tale thou. Like flying a plane on instruments, trust them in the fog.
        >
        > Outside are a vast spectrum of freqs below 50 hz. No sensed hum or vibration. Go into a structure and reasonance kicks the hum in. A parked, quiet car does the same.
        >
        > Check out articles on sound propagation from tunnels. Same phenomea that is studied and accepted, and can be applied here. A long planar diatributor acts different than a point source. Geometrically it attenuates less than a point source. Couple with Long LF sound waves known as Rayleigh interface waves and theres the part of the story to travel of the sound waves that induce hum
        >
        > Testing to find the epicenter takes a long day and a good distance off the suspect line taking measures, collecting data. My results here, always have the lines as the epicenter.
        >
        > Not saying its the only source, but here, it is.
        > Steve
        >
        > Sent from Steve's iPhone and I appologize for typo's
        >
        > On Mar 8, 2013, at 4:43 PM, "technicanalyst" <mr.steven.brown@...> wrote:
        >
        > > Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?
        > >
        > >
        >
      • Steve Kohlhase
        Marygaylor For now, coping techniques that many talk about that work for you is about all we can do.  Most use masking of HEPA. nosie HVAC at work, whole
        Message 3 of 12 , Mar 9, 2013
        • 0 Attachment
          Marygaylor
          For now, coping techniques that many talk about that work for you is about all we can do.  Most use masking of HEPA. nosie HVAC at work, whole house fan in the summer do help with the audible effects. Since I am researching it, I haven't tried the other coping techniques menetioned by others  and I don't accept just living with it.  Even with the soothing effects the body is surely still being saturated with ILFN/ LFN and whatever it casues over time. I am confronting our Federal Energy regualtory Commission on getting some localized issues dealth with for misoperations of 2 compressors casuing vibrations and LF rumbling.  Resulting from my expanding research I have also been trying to engage action about the revealtion of the wide ranging sound wave induced hum here in CT from the 3 buried high pressure 24- 36 inch lines.  If it weren't for these problems, everything would be fine.  But since it is so bad, and so urgent exposing and publicly acknowledging it is priority one.  Right now the sufferers are so fragmented in getting a message out and under attended to by the authorities. 
           
          The good news is a few of us are onto a solid explanation that hasn't been looked into for 30 years (why??).  The bad news is like you found, dissmisal of the problem and no authority wants to admit it is real and it is harmful.  My Senators, DEP, FERC, etc don't want to touch this, and haven't been forced to becasue only a few pursue them.  There are mental health issues occurring from it, likely health issues.  As well as occurances of strange, unexplaianble diasters in mother nature where these lines and the hum are plausible reasons.
           
          So the first thing we need to do is to get attention to the symptoms and an outcry to congress, FERC and publicity in the papers to get lathargic attidues changed.  I recently gave facts, information as evidence of intense Hum I have from my mapping project from 2 years ago, done in Adam Lanza's  neighborhood in Newtown and the intense level of hum in our area the week before the tradegy and submitted to the GT State Crimes unit and all they said was " not enough information".  Doesn't it make sense there isn't enough information if what we are doing here on this forum may be where all the information really is and authorities aren't willing to open their eyes to this problem,,,  So you see how big a problem we have at this time of willful ignornace. 
           
          I hope to get another article published soon to enlighten more people  about teh hum and generate complaining to the authorities.  You can see my map of hum reports in the file section and you will see how many in CT there are.   I beleive if the CT population is aware of the hum story those that are experieincing known or unbeknowst symstoms inside  their homes/ businesses, schools, etc of ears ringing, chronic insomnia in the last 3.5 years,, aggressive behaviors, depression, ear pressure, body sensations like tingly feet, never before migranes, vertigo, nausea unexplained changes in animal habitats and behavior, maybe something will get done.
           
          All I can say right now is refer the company to FERC in Washington (do it in writing), and have them refer to the problem in CT.  The company will not willing help once they understand the problem . If anything, it can only help  bolster my efforts.  Stay active, push the point of the Hum/ surface vibrations out to whomever you are comfortable to sdo so, regardless if you agree with my claims or not.  .
           
          Steve
           
           
          PS- I collect so much information and may repeat myself, but for the map and my intrigue to research your area, what town and state do you experience this

          From: "marygaylor168@..." <marygaylor168@...>
          To: humforum@yahoogroups.com
          Sent: Saturday, March 9, 2013 6:38 AM
          Subject: Re: HUM_FORUM: A way to locate source of low-frequency noise
           

          Hi, Reading your post, I say you know exactly what is, I would say, a major cause of the HUM...my home has been bombarded for the past three years, and to cut a very long story short, I have been in touch with the company responsible...who asked me what I wanted them to do. Can I ask do you know what can be done to a property, some sort of insulation or attenuators. I would like to go back to them with a plan....because although they appear to have tried, they can't stop it affecting my home. Any advice would be very welcome.

          --- In mailto:humforum%40yahoogroups.com, Copsne <c_o_p_s_ne@...> wrote:
          >
          > Thats what common sense would think, including me in the beginning. Acoustic tools will tell the tale thou. Like flying a plane on instruments, trust them in the fog.
          >
          > Outside are a vast spectrum of freqs below 50 hz. No sensed hum or vibration. Go into a structure and reasonance kicks the hum in. A parked, quiet car does the same.
          >
          > Check out articles on sound propagation from tunnels. Same phenomea that is studied and accepted, and can be applied here. A long planar diatributor acts different than a point source. Geometrically it attenuates less than a point source. Couple with Long LF sound waves known as Rayleigh interface waves and theres the part of the story to travel of the sound waves that induce hum
          >
          > Testing to find the epicenter takes a long day and a good distance off the suspect line taking measures, collecting data. My results here, always have the lines as the epicenter.
          >
          > Not saying its the only source, but here, it is.
          > Steve
          >
          > Sent from Steve's iPhone and I appologize for typo's
          >
          > On Mar 8, 2013, at 4:43 PM, "technicanalyst" <mr.steven.brown@...> wrote:
          >
          > > Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?
          > >
          > >
          >

        • iprefertruth
          Hi, Did you see the results of the Zug Island research ? They had a device which seems similar to what you describe here. They were able to get a direction on
          Message 4 of 12 , Dec 20, 2014
          • 0 Attachment
             
            Hi,
            Did you see the results of the Zug Island research ?
            They had a device which seems similar to what you describe here.
            They were able to get a direction on the noise source,
            as you say here,
             by analysing which microphone picks it up first  (to put it simply!).
            I had not heard of their two 'mike' device before, but it acts like the human ears,
            whereby we know which direction a sound comes from, by the
            very tiny delay between one ear receiving it, and the other ear's response.
            Best Wishes,
            R.S.J.Mann,
            LFNSHelp, England.
             
            In a message dated 07/03/2013 20:27:12 GMT Standard Time, mr.steven.brown@... writes:
             

            I thought of a way to ascertain the direction or bearing from which low-frequency noise is coming. If bearings are obtained from two widely separated locations, it should be possible to locate the source of the noise on a map where the bearing lines intersect.

            The method entails detecting the noise with a microphone, amplifying it, electronically filtering it to isolate the noise from other sounds picked up by the microphone, and displaying it as a waveform on an oscilloscope. When this is accomplished the next step is to do this with two microphones, separated by a few meters, and display both waveforms on the screen of a dual-channel oscilloscope. When one microphone is positioned closer to the source of noise than the other, the waveform from that microphone will display to the left of the waveform from the other microphone on the screen. Position the two microphones for the greatest separation of waveforms displayed. The direction from which the noise is emanating will be along a straight line intersecting the two microphones, and pointing in the direction of the microphone at which the noise arrives first. That will be the one that displays the waveform to the left of the other one on the screen.

            Using identical microphones, the two waveforms should appear identical and differ only in phase, indicating the difference in time of arrival. It is necessary to adjust the spacing between the two microphones so that the peaks of the same cycle can be displayed. The spacing between peaks depends on the sweep rate of the oscilloscope and the velocity of sound. For example, at 40 Hz the duration of 1 cycle is 25 milliseconds. If the sweep rate of the oscilloscope is set to 5 milliseconds per division, one full cycle will display across 5 horizontal divisions. If there are 10 divisions or ruler marks displayed along the horizontal axis on the scope, one full sweep takes 50 milliseconds and two complete cycles of the 40 Hz waveform will be displayed. Each half cycle will cover 12.5 mS, spanning 2.5 divisions. To get the peaks of the two waveforms to display 2 divisions apart, it is necessary for the difference in time of arrival at the two microphones to be 10 milliseconds. As th e speed of sound in air is 343.2 meters per second, it travels 3.432 meters in 10 milliseconds. That is how far the microphones need to be apart in order to display waveforms separated in phase by two divisions on the screen of the scope.

            For picking up low-frequency sound, I have noticed that inexpensive electret microphone elements seem to work well. There is really no need to invest in expensive microphones that have good low-frequency response. It also isn't necessary to invest in an oscillosope, because software is available to use the sound card of a laptop computer to diplay audio waveforms on the screen. Stereo sound consists of two channels which can be diplayed simultaneously. I am thinking of using this method to locate the source of low-frequency noise pollution in the area where I live. I suspect it is a municipal water treatment tower 3 miles away. This method could confirm that, or it could point to a different source.

             
             
             
             



             

          • iprefertruth
            In a message dated 09/03/2013 12:24:49 GMT Standard Time, marygaylor168@btinternet.com writes: Steve, if a gas pipeline is a source of low-frequency noise, I
            Message 5 of 12 , Dec 20, 2014
            • 0 Attachment
               
               
              In a message dated 09/03/2013 12:24:49 GMT Standard Time, marygaylor168@... writes:
              Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?
              Hi,
              I have listened to large gas pipes , which were suspected years ago.....
              I heard nothing but a gentle 'hiss', definitely not a low 'hum'.
              As I have said many times before, when people claim that gas pipes
              may be culprits,
              go and listen with a stethoscope, or lie down and put your ear to the ground
              (as I did) (keeping the other ear open for approaching cars, if lying in a public as I did !)
              If there is a hum, there, surely you should hear it, as I believe that gas
              pipes are only about 2 metres below the surface.
              The fact that I could hear a high-ish frequency 'hiss', ays to me that a low hum would
              transmit easier through soil etc., than a higher frequency sound.
              Generally I do not believe that low hums can travel long distances through soil, earth, rock, etc.
              I think that the many different densities of material will muffle  any sound coming from them.
              Every time a sound meets a different density of 'stuff ' , it loses some energy.
              Plus, as Prof Leventhal said many years ago, it then has to have some
              method of escaping from the soil into the air, so you could hear it :
               it would need to have enormous energy
               to get out under those circumstances. 
               It needs a transmission method
               of some sort , to escape......
              I am looking mostly at above-ground, airborne sources.
              Our trains round here often trundle by, a couple of hundred yards away, and
              in recent years, they seem to have different-sounding engines :
              often recently, I have detected a deep, heavy, very low hum,
               and have learnt now to expect a train in a minute or so.
              That OUGHT to tell us how far its LFN is travelling ....?
              They do about 30 m.p.h. just here.....
              Someone please work it out ?
              (I'm a bit rusty on maths !)
              But that says to me that a train like that will be covering 
               a certain area either side of the track, maybe half a mile ?
               and lasting a few minutes, as the train rumbles by.....
              Imagine many, many trains all trundling around a city?
              Couldn't you get a 'piling up' effect of all their hums,
              especially where the areas they sound overlap....
              Then maybe add in loads of other LFN sources,
              of similar frequencies,
               and you could get a general hum / hub-bub,
              that is very difficult to pinpoint .
              Let's try to keep searching and testing wherever we can, folks....
              I don't suffer as much as I used to,
              but that I think is due  mainly to ditching prescription 'tranx',
              which I was told on good authority could make hearing too sensitive.
              Plus if you're stressed, you could react more  to a nuisance noise,
              plus some medical conditions make super-sensitive hearing, apparenty.
              As I have to tell enquirers, there's no simple answer,
              and there may be many different answers,
              depending on personal circumstances,
              plus environmental circumstances.....
              That's why I am having to cast around now for a database
               or website that could hold my 'Information Pack',
              I seem to have had it removed from the one that held it for a few years.....
              Am trying just now to find out what happened,
              why I cannot find it there.....
              It is SO useful to have it available online for people to read,
              because it is so much quicker for people to follow a link on 'The Net',
               rather than having to write on paper,
              get me to print 30 pages, get it weighed, pay money to post, etc.
               
              Could 'Humforum' take it, perhaps?
               
              Any possible solutions would be much appreciated.
               
              Best Wishes to all,
              and ' Happy Christmas'.
               
              R.S.J.Mann.
              'LFNS Help',
              England.
              =========================================

               
            • Copsne
              Mary I ve tried this so many times at the start. When one stands over these lines and dismisses these systems as a source of hum causing sound waves because
              Message 6 of 12 , Dec 21, 2014
              • 0 Attachment
                Mary
                I've tried this so many times at the start. When one stands over these lines and dismisses these systems as a source of hum causing sound waves because they don't hear a hiss (which is at different, higher unassociated frequencies) they are throwing the baby out with the bath water.  They need to consider more, complex scientific explanation in their search. 
                Many of us  believe the human ear doesn't easily hear the hum because the mechanism of the hum is low/ infrasonic sound. And as I found, something needs to be put into reasonance or some acoustical interaction with large enclosed spaces. 
                Standing and listening for the hum at these lines is futile. The lines are the sound source, not the affected reasonat structure, so they don't exhibit a hum causing vibration. 
                What any scientist would do is use tools appropriate for the purpose. As I've said many times a decent laptop and acoustic measuring tools like FFT or 1/3 octave analyzer taking measurements starting at these lines and working away from them will show in many cases that the line locations are the epicenter of the source. But this takes allot of time and some technical training. Think of flying a jet airliner without instruments, highly difficult if even possible. 
                Because LF Raleigh sound waves can be as long as 50 feet or more for one cycle, they do not attenuate for long distances, so thats why it is so hard to pinpoint a source. Especially a line source vs a point source. 
                My research fits that done in other fields of study like tunnel environmental engineering that linear sources radiate the Raleigh waves which interact with enclosures (buildings) at their natural reasonat frequency.  Causing surfaces to vibrate ( that tingly feeling we have in our feet) in the building, in turn inducing the tonal hum.
                Don't confuse Rayleigh waves as vibrations. There are no vibrations going through the ground unless they act with something that goes into resonance. 
                Go to Youtube and watch the demonstrations of reasonance and tuning fork sound boxes. Same thing as what I call gas pipeline syndrome

                Anyway this is what I have submitted to our State and Federal government and pursuing in varies ways, including legally. I would like to see others pursue this avenue of research 

                Sorry to be long winded. So back to writing a news article on the matter in CT

                Happy Holidays

                Steve

                Sent from Steve's iPhone and I appologize for typo's and auto corrects

                On Dec 21, 2014, at 12:10 AM, Tobypaws2002@... [humforum] <humforum@yahoogroups.com> wrote:

                 

                 
                 
                In a message dated 09/03/2013 12:24:49 GMT Standard Time, marygaylor168@... writes:
                Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?
                Hi,
                I have listened to large gas pipes , which were suspected years ago.....
                I heard nothing but a gentle 'hiss', definitely not a low 'hum'.
                As I have said many times before, when people claim that gas pipes
                may be culprits,
                go and listen with a stethoscope, or lie down and put your ear to the ground
                (as I did) (keeping the other ear open for approaching cars, if lying in a public as I did !)
                If there is a hum, there, surely you should hear it, as I believe that gas
                pipes are only about 2 metres below the surface.
                The fact that I could hear a high-ish frequency 'hiss', ays to me that a low hum would
                transmit easier through soil etc., than a higher frequency sound.
                Generally I do not believe that low hums can travel long distances through soil, earth, rock, etc.
                I think that the many different densities of material will muffle  any sound coming from them.
                Every time a sound meets a different density of 'stuff ' , it loses some energy.
                Plus, as Prof Leventhal said many years ago, it then has to have some
                method of escaping from the soil into the air, so you could hear it :
                 it would need to have enormous energy
                 to get out under those circumstances. 
                 It needs a transmission method
                 of some sort , to escape......
                I am looking mostly at above-ground, airborne sources.
                Our trains round here often trundle by, a couple of hundred yards away, and
                in recent years, they seem to have different-sounding engines :
                often recently, I have detected a deep, heavy, very low hum,
                 and have learnt now to expect a train in a minute or so.
                That OUGHT to tell us how far its LFN is travelling ....?
                They do about 30 m.p.h. just here.....
                Someone please work it out ?
                (I'm a bit rusty on maths !)
                But that says to me that a train like that will be covering 
                 a certain area either side of the track, maybe half a mile ?
                 and lasting a few minutes, as the train rumbles by.....
                Imagine many, many trains all trundling around a city?
                Couldn't you get a 'piling up' effect of all their hums,
                especially where the areas they sound overlap....
                Then maybe add in loads of other LFN sources,
                of similar frequencies,
                 and you could get a general hum / hub-bub,
                that is very difficult to pinpoint .
                Let's try to keep searching and testing wherever we can, folks....
                I don't suffer as much as I used to,
                but that I think is due  mainly to ditching prescription 'tranx',
                which I was told on good authority could make hearing too sensitive.
                Plus if you're stressed, you could react more  to a nuisance noise,
                plus some medical conditions make super-sensitive hearing, apparenty.
                As I have to tell enquirers, there's no simple answer,
                and there may be many different answers,
                depending on personal circumstances,
                plus environmental circumstances.....
                That's why I am having to cast around now for a database
                 or website that could hold my 'Information Pack',
                I seem to have had it removed from the one that held it for a few years.....
                Am trying just now to find out what happened,
                why I cannot find it there.....
                It is SO useful to have it available online for people to read,
                because it is so much quicker for people to follow a link on 'The Net',
                 rather than having to write on paper,
                get me to print 30 pages, get it weighed, pay money to post, etc.
                 
                Could 'Humforum' take it, perhaps?
                 
                Any possible solutions would be much appreciated.
                 
                Best Wishes to all,
                and ' Happy Christmas'.
                 
                R.S.J.Mann.
                'LFNS Help',
                England.
                =========================================

                 

              • Tim Kramer
                Fyi, Hum has been significant the last few weeks. It went silent this morning in Denver 80214 On Sun, Dec 21, 2014 at 9:52 AM, Copsne c_o_p_s_ne@yahoo.com
                Message 7 of 12 , Dec 21, 2014
                • 0 Attachment
                  Fyi, Hum has been significant the last few weeks.  It went silent this morning in Denver 80214

                  On Sun, Dec 21, 2014 at 9:52 AM, Copsne c_o_p_s_ne@... [humforum] <humforum@yahoogroups.com> wrote:
                   

                  Mary
                  I've tried this so many times at the start. When one stands over these lines and dismisses these systems as a source of hum causing sound waves because they don't hear a hiss (which is at different, higher unassociated frequencies) they are throwing the baby out with the bath water.  They need to consider more, complex scientific explanation in their search. 
                  Many of us  believe the human ear doesn't easily hear the hum because the mechanism of the hum is low/ infrasonic sound. And as I found, something needs to be put into reasonance or some acoustical interaction with large enclosed spaces. 
                  Standing and listening for the hum at these lines is futile. The lines are the sound source, not the affected reasonat structure, so they don't exhibit a hum causing vibration. 
                  What any scientist would do is use tools appropriate for the purpose. As I've said many times a decent laptop and acoustic measuring tools like FFT or 1/3 octave analyzer taking measurements starting at these lines and working away from them will show in many cases that the line locations are the epicenter of the source. But this takes allot of time and some technical training. Think of flying a jet airliner without instruments, highly difficult if even possible. 
                  Because LF Raleigh sound waves can be as long as 50 feet or more for one cycle, they do not attenuate for long distances, so thats why it is so hard to pinpoint a source. Especially a line source vs a point source. 
                  My research fits that done in other fields of study like tunnel environmental engineering that linear sources radiate the Raleigh waves which interact with enclosures (buildings) at their natural reasonat frequency.  Causing surfaces to vibrate ( that tingly feeling we have in our feet) in the building, in turn inducing the tonal hum.
                  Don't confuse Rayleigh waves as vibrations. There are no vibrations going through the ground unless they act with something that goes into resonance. 
                  Go to Youtube and watch the demonstrations of reasonance and tuning fork sound boxes. Same thing as what I call gas pipeline syndrome

                  Anyway this is what I have submitted to our State and Federal government and pursuing in varies ways, including legally. I would like to see others pursue this avenue of research 

                  Sorry to be long winded. So back to writing a news article on the matter in CT

                  Happy Holidays

                  Steve

                  Sent from Steve's iPhone and I appologize for typo's and auto corrects

                  On Dec 21, 2014, at 12:10 AM, Tobypaws2002@... [humforum] <humforum@yahoogroups.com> wrote:

                   

                   
                   
                  In a message dated 09/03/2013 12:24:49 GMT Standard Time, marygaylor168@... writes:
                  Steve, if a gas pipeline is a source of low-frequency noise, I would expect it to be really noticeable to someone standing on the ground right over the pipeline. This would be especially true if it sends vibrations through the ground. Has anyone tried this?
                  Hi,
                  I have listened to large gas pipes , which were suspected years ago.....
                  I heard nothing but a gentle 'hiss', definitely not a low 'hum'.
                  As I have said many times before, when people claim that gas pipes
                  may be culprits,
                  go and listen with a stethoscope, or lie down and put your ear to the ground
                  (as I did) (keeping the other ear open for approaching cars, if lying in a public as I did !)
                  If there is a hum, there, surely you should hear it, as I believe that gas
                  pipes are only about 2 metres below the surface.
                  The fact that I could hear a high-ish frequency 'hiss', ays to me that a low hum would
                  transmit easier through soil etc., than a higher frequency sound.
                  Generally I do not believe that low hums can travel long distances through soil, earth, rock, etc.
                  I think that the many different densities of material will muffle  any sound coming from them.
                  Every time a sound meets a different density of 'stuff ' , it loses some energy.
                  Plus, as Prof Leventhal said many years ago, it then has to have some
                  method of escaping from the soil into the air, so you could hear it :
                   it would need to have enormous energy
                   to get out under those circumstances. 
                   It needs a transmission method
                   of some sort , to escape......
                  I am looking mostly at above-ground, airborne sources.
                  Our trains round here often trundle by, a couple of hundred yards away, and
                  in recent years, they seem to have different-sounding engines :
                  often recently, I have detected a deep, heavy, very low hum,
                   and have learnt now to expect a train in a minute or so.
                  That OUGHT to tell us how far its LFN is travelling ....?
                  They do about 30 m.p.h. just here.....
                  Someone please work it out ?
                  (I'm a bit rusty on maths !)
                  But that says to me that a train like that will be covering 
                   a certain area either side of the track, maybe half a mile ?
                   and lasting a few minutes, as the train rumbles by.....
                  Imagine many, many trains all trundling around a city?
                  Couldn't you get a 'piling up' effect of all their hums,
                  especially where the areas they sound overlap....
                  Then maybe add in loads of other LFN sources,
                  of similar frequencies,
                   and you could get a general hum / hub-bub,
                  that is very difficult to pinpoint .
                  Let's try to keep searching and testing wherever we can, folks....
                  I don't suffer as much as I used to,
                  but that I think is due  mainly to ditching prescription 'tranx',
                  which I was told on good authority could make hearing too sensitive.
                  Plus if you're stressed, you could react more  to a nuisance noise,
                  plus some medical conditions make super-sensitive hearing, apparenty.
                  As I have to tell enquirers, there's no simple answer,
                  and there may be many different answers,
                  depending on personal circumstances,
                  plus environmental circumstances.....
                  That's why I am having to cast around now for a database
                   or website that could hold my 'Information Pack',
                  I seem to have had it removed from the one that held it for a few years.....
                  Am trying just now to find out what happened,
                  why I cannot find it there.....
                  It is SO useful to have it available online for people to read,
                  because it is so much quicker for people to follow a link on 'The Net',
                   rather than having to write on paper,
                  get me to print 30 pages, get it weighed, pay money to post, etc.
                   
                  Could 'Humforum' take it, perhaps?
                   
                  Any possible solutions would be much appreciated.
                   
                  Best Wishes to all,
                  and ' Happy Christmas'.
                   
                  R.S.J.Mann.
                  'LFNS Help',
                  England.
                  =========================================

                   


                Your message has been successfully submitted and would be delivered to recipients shortly.