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Difference in Hum at 11,700 feet

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  • marykwart
    I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don t (didn t hear it around Buena Vista, Colorado).
    Message 1 of 8 , Oct 3, 2011
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      I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.
    • Margaret
      Wow. Fascinating. Scientific explanation anyone? Maggie ... sometimes hear the hum and sometimes don t (didn t hear it around Buena Vista, Colorado). When I
      Message 2 of 8 , Oct 4, 2011
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        Wow.  Fascinating.  Scientific explanation anyone? Maggie

        --- In humforum@yahoogroups.com, "marykwart" <mkwart@...> wrote:
        >
        > I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.
        >
      • Jim
        ... It would be presumptuous for me to offer an explanation , but can offer a hypothesis. If you assume that the hum is truly a sound wave, it will move at
        Message 3 of 8 , Oct 4, 2011
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          > Wow. Fascinating. Scientific explanation anyone?

          It would be presumptuous for me to offer an "explanation", but can offer a
          hypothesis.

          If you assume that the hum is truly a sound wave, it will move at the "speed of
          sound". A lot of times that is thrown around as a constant, but it varies based
          on a number of things. I'm not an expert, but I believe most of the variation is
          due to air density.

          If you are standing at ground level and measure the speed of sound you'll get
          some value. If you get up on the roof say (just making up a number) 50 feet
          higher and measure the speed of sound, it will probably be slightly faster
          because air decreases in density as you go higher SO LONG AS TEMPERATURE DOESN'T
          CHANGE.

          But temperature does change. And colder air is denser than warm air. (That's why
          warm air rises--it's "lighter" in effect. Without that, there would be no hot
          air balloons floating around.)

          So instead of going up 50 feet and checking the speed of sound, say you go up
          50,000 feet. Now if you measure the speed of sound, it will be slower than on
          the ground.

          There should be some point where the speed of sound is it's fastest--the air is
          less dense and hasn't become cold enough for air density to increase faster than
          the rise in altitude would make it fall. So at some point, there is an altitude
          where sound travels at its fastest. It seems possible that if you were below
          this things would "sound" one way based on how the sound's wavefront changed
          because of the differences in speed as it traveled. If you were above it, it
          could sound different because the wavefront would be dealing with something that
          is "upside down" compared to how speed is affected by minimal changes in height
          at ground level.

          At ground level, the wavefront "over" us travels faster and will hit us sooner
          than the wavefront "under" us. That could account for it sounding like it's
          "above" the observer. Above the critical altitude, this would be reversed and
          the wavefront "over" us would now travel slower and hit us later than the
          wavefront "under" us. Maybe that could account for it sounding like it's "below"
          the observer.

          Lots of assumptions and simplifications in there. I'm also an electrical
          engineer, not a physicist. So I could well be wrong. But at first glance, it
          does seem like there is at least a reasonable hypothesis that could be offered.
          I guess one question it would be interesting to answer is where the "crossover"
          between the speed of sound increasing with altitude and decreasing with altitude
          occurs. As one of my old professors often put in the text book he'd written,
          determination of that is left as an exercise for the reader... :-)

          Thanks,
          Jim
        • Copsne
          I ll take the challenge. Cant look into it for a day or two thou. Either way I ll collect the data points Steve Sent from Steve s iPhone and I appologize for
          Message 4 of 8 , Oct 4, 2011
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            I'll take the challenge. Cant look into it for a day or two thou. Either way I'll collect the data points

            Steve

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

            On Oct 4, 2011, at 2:12 PM, "Margaret" <coatesmargaret@...> wrote:

             

            Wow.  Fascinating.  Scientific explanation anyone? Maggie


            --- In humforum@yahoogroups.com, "marykwart" <mkwart@...> wrote:
            >
            > I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.
            >

          • annereeder
            Is a very interesting post, Margaret. I don t have an explanation, but one thought is, maybe at 11,700 ft. up, she may have got away from the electro smog
            Message 5 of 8 , Oct 4, 2011
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              Is a very interesting post, Margaret.  I don't have an explanation, but one thought is, maybe at 11,700 ft. up, she may have got away from the electro smog below at that altitude, but could have something traveling with her that is still connecting her to it below.
              Anne
               

               

              Wow.  Fascinating.  Scientific explanation anyone? Maggie


              --- In humforum@yahoogroups.com, "marykwart" <mkwart@...> wrote:
              >
              > I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.
              >

            • Margaret
              Hello Anne, nice to see a post from you. Electrosmog might fit. I ve never before read anything like that on the forum, Mary. It could be very pertinent.
              Message 6 of 8 , Oct 5, 2011
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                Hello Anne, nice to see a post from you. Electrosmog might fit. I've never before read anything like that on the forum, Mary. It could be very pertinent. Maggie

                --- In humforum@yahoogroups.com, "annereeder" <annereeder@...> wrote:
                >
                > Is a very interesting post, Margaret. I don't have an explanation, but one thought is, maybe at 11,700 ft. up, she may have got away from the electro smog below at that altitude, but could have something traveling with her that is still connecting her to it below.
                > Anne
                >
                >
                >
                >
                > Wow. Fascinating. Scientific explanation anyone? Maggie
                >
                >
                > --- In humforum@yahoogroups.com, "marykwart" <mkwart@> wrote:
                > >
                > > I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.
                > >
                >
              • Copsne
                Nice. I still have to do home work on locations mentioned than I ll weigh in. Re engaged with FERC right now on pipelines and compressors as priorty 1 Sent
                Message 7 of 8 , Oct 7, 2011
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                  Nice. I still have to do home work on locations mentioned than I'll weigh in. Re engaged with FERC right now on pipelines and compressors as priorty 1

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

                  On Oct 4, 2011, at 2:41 PM, Jim <w4jbm@...> wrote:

                   

                  > Wow. Fascinating. Scientific explanation anyone?

                  It would be presumptuous for me to offer an "explanation", but can offer a
                  hypothesis.

                  If you assume that the hum is truly a sound wave, it will move at the "speed of
                  sound". A lot of times that is thrown around as a constant, but it varies based
                  on a number of things. I'm not an expert, but I believe most of the variation is
                  due to air density.

                  If you are standing at ground level and measure the speed of sound you'll get
                  some value. If you get up on the roof say (just making up a number) 50 feet
                  higher and measure the speed of sound, it will probably be slightly faster
                  because air decreases in density as you go higher SO LONG AS TEMPERATURE DOESN'T
                  CHANGE.

                  But temperature does change. And colder air is denser than warm air. (That's why
                  warm air rises--it's "lighter" in effect. Without that, there would be no hot
                  air balloons floating around.)

                  So instead of going up 50 feet and checking the speed of sound, say you go up
                  50,000 feet. Now if you measure the speed of sound, it will be slower than on
                  the ground.

                  There should be some point where the speed of sound is it's fastest--the air is
                  less dense and hasn't become cold enough for air density to increase faster than
                  the rise in altitude would make it fall. So at some point, there is an altitude
                  where sound travels at its fastest. It seems possible that if you were below
                  this things would "sound" one way based on how the sound's wavefront changed
                  because of the differences in speed as it traveled. If you were above it, it
                  could sound different because the wavefront would be dealing with something that
                  is "upside down" compared to how speed is affected by minimal changes in height
                  at ground level.

                  At ground level, the wavefront "over" us travels faster and will hit us sooner
                  than the wavefront "under" us. That could account for it sounding like it's
                  "above" the observer. Above the critical altitude, this would be reversed and
                  the wavefront "over" us would now travel slower and hit us later than the
                  wavefront "under" us. Maybe that could account for it sounding like it's "below"
                  the observer.

                  Lots of assumptions and simplifications in there. I'm also an electrical
                  engineer, not a physicist. So I could well be wrong. But at first glance, it
                  does seem like there is at least a reasonable hypothesis that could be offered.
                  I guess one question it would be interesting to answer is where the "crossover"
                  between the speed of sound increasing with altitude and decreasing with altitude
                  occurs. As one of my old professors often put in the text book he'd written,
                  determination of that is left as an exercise for the reader... :-)

                  Thanks,
                  Jim

                • annereeder
                  Hi Mary, I was looking at the area of the location where you camped at 11,700 feet and did not hear the hum. I realized that there was not enough population
                  Message 8 of 8 , Oct 8, 2011
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                    Hi Mary,
                     
                    I was looking at the area of the location where you camped at 11,700 feet and did not hear the hum.   I realized that there was not enough population there to create a lot of electro smog.   I think that it could be possible that the electromagnetic fields of the mountain itself from all the different minerals there, could be a possible cause of the hum.   Perhaps when you reached the top you were then above them causing the hum to cease.  I am not a scientist, just someone who has spent nine years with the hum, but have been mostly free of it since 2005.
                     
                    It must be a wonderful feeling being able to climb those mountains when you finally get to the top.  I have spent some time up there traveling through the Colorado Rockies.   I have only reached the top of those mountains  that had a road up that was passable for vehicles.  I wish you good luck there.  Anne
                     
                    ----- Original Message -----
                    From: marykwart
                    Sent: Monday, October 03, 2011 9:37 PM
                    Subject: HUM_FORUM: Difference in Hum at 11,700 feet

                     

                    I recently backpacked the Colorado Trail from Denver to Durango. I sometimes hear the hum and sometimes don't (didn't hear it around Buena Vista, Colorado). When I do hear it is always above my head and to the right, no matter how my orientation is-- (I only hear it at night or in the early morning when I am usually laying down). An interesting thing happened when I camped at 11,700 feet--the hum was no longer perceived to be above my head, but below it. That was the only change--often the hum is more persistent in wilderness than in cities. When I camped at Baldy Lake on the Colorado Trail in a rock cirque, the hum was continuous and loud.

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