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Radar? Sonar? Solve A Mystery Please!

  1. Feb 4, 2009 #1
    I have a strange mystery. My house sings! I am wondering if anyone can take a guess at what could cause this.

    I have occasional insomnia, which leaves me lying there in bed in the wee hours of the night when it is dead silent. Well, this morning was one of those. I woke up around 1:00 am, and laid there silently as to not wake up the rest of the house. Around 2:30, my house starts to sing/hum. :surprised This HAS happened before, but it doesn't happen often.

    So a little background. A little too much info, but I believe it is necessary. Yes, I live in Seattle Washington. I am about a half a mile from Puget Sound, so often in the middle of the night I can hear ships going up or down the Sound to my west. I can also often hear trains down in the valley to my east. I am near the airport, although I always hear this tone when the airport is silent. (I assume the airport has a noise curfew) Due west from me (across Puget Sound), is Bremerton naval base.

    Now, back to this morning. The tone that my house sings is possibly a b flat or a b (my pitch is not so perfect anymore) so I would assume around 906 to 934 would be the frequency. It will change in loudness, but never tone. I decided since I was wide awake to try to analyze it, so I started paying attention to everything else around me. I could hear a low rumble in the distance, possibly a ship, but sounded more like a very heavy train. Soon after, I heard train whistles. So I will assume it was a train, but it could have been a small ship (it didn't have the throb of a large ship).

    By about 3:40, my heater turned on and I was unable to really hear the tone any more, and when the heater shut off, I was finally falling back asleep. So I didn't pay close attention (as I didn't want to wake back up) but I don't think I could hear the tone after the heater shut off. So it went on for 70 minutes for sure, but apparently not 90 minutes. This tone does vary greatly in volume, sometimes inaudible, sometimes quite loud (yet still background noise) yet always the same tone. The loud/quiet doesn't seem to follow any pattern. Since I don't want to wake the whole house, I have never wandered around to see if it can be heard outside the bedroom or outside the house. I have no idea if it is something making SPECIFICALLY that tone, or if it is a broader spectrum sound, and my house (perhaps the wiring) is resonating in that specific tone (like a harmonic). And I haven't heard of anyone else hearing this in my area.

    So quick recap. It could have something to do with the airport, although I would expect the airport to be consistent. It could have something to do with shipping, but the rumble I heard did not sound like a ship, and it doesn't take 70 (plus) minutes for a ship to pass. It could have something to do with the Navy at Bremerton, although I have only heard of the controversial sonar (that people can hear in the middle of the night) being used up at Whidbey, which is quite a ways north. But I am leaning more military...

    Anyone want to take a stab? Know about military sonar or radar use? And Why that specific frequency? Or is my house just happy at that early time of the morning? :rofl:
  2. jcsd
  3. Feb 4, 2009 #2

    Chi Meson

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    WHat kind of heating do you have?

    And, does this noise vary significantly with the seasons? Does opening a window have any effect on the loudness?

    Regarding resonance, 900 Hz will resonate in a space of just over 1 foot in length. So a room or the entire house is unlikely to be causing that. YOu would notice a huge difference by moving furniture, or opening a door.

    Is there a dish on the roof? lightning rods? anything else? DOes the wind seem to have any effect?

    Navy sonar uses "pings" not 70 minute long squeals at 900 Hz. The controversial stuff, I think, is extremely low frequencies.

    Telephone signals (through the copper wires) are carried in a range that includes 900-1000 Hz, but I don't see how...

    Do your toilets run on slightly? We had a toilet valve that caused our copper pipes to sing every time it was flushed.

  4. Feb 4, 2009 #3
    1.Because of temperature variations in the atmosphere sounds tend to travel further(because of refraction) at night than they do during the day.
    2.Plumbing systems are notorious for producing sounds due to airlocks valves etc.We had a problem similar to Chi Mesons but from a ball valve feeding a tank.
    3.Have you had your hearing checked and could you be suffering from intermittent tinnitus?
  5. Feb 4, 2009 #4
    Hi! Thanks for posting, I will answer in order?

    Chi -
    We have oil heat, forced air.

    I have only heard this twice, so I can't answer if it changes with the season. This is somewhat new.

    Good point about resonance.

    No dish or lightning rods, and there was no wind last night.

    Re the low frequency, I brought it up because I can remember hearing a looong time ago about residents hearing noise thought related to the low frequency stuff, but I can't find any articles to find WHAT they heard. And you are right about the sonar using a ping, a DOH moment for me! :redface:

    Telephone wiring is an interesting point. But as you say, how? But is it possible?

    No, it isn't plumbing. All the plumbing is on one half of the house, so it would sound very "directional" to me. I have had problems like that in the past, too, but this isn't it.

    Dadface -

    Good point about the atmospheric conditions. Would explain hearing the radar at the airport, but it definitely does not sound like their radar. (there used to be a "lovers lane" right next to the radar tower.....) What else could travel at night? (sound wise)

    Plumbing - answered above

    Good point! I do have tinnitus, but this isn't it.

    This sound is definitely THERE in the house, not in my head, not directional. I guess next time (if there is a next time) I will have to risk waking the family and pets and walk around the house, maybe even outside (or not:biggrin: don't need to flash the neighbors). Maybe I should keep a log of weather conditions, etc. Last time I heard this it was VERY cold outside, and the heater was on half of the time. Last night was very warm, so the heater did not come on for several hours. Maybe it would clarify if I explain the sound better. It is as if someone played a b flat (or very close to that note) on a keyboard and held the tone, then turned the volume up and down, but randomly, no regular pattern at all. it doesn't come from any direction, it is all around me in the air.
  6. Feb 4, 2009 #5


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    I did some investigation of an issue in a skyscraper in center city Philadelphia, where the building received the radio stations being broadcast next-door. And I mean that exactly as it sounds: the building received the radio broadcasts. The rooms in the building directly across from the broadcast tower in the spire of the adjacent building would not only hum, but a stethescope placed on a metal surface (the window frames, for example) would allow you to actually listen to the broadcast and any speaker or earphone (computer speakers, headphones, telephones), would play the radio broadcast. Unfortunately, the phenomena was intermittent, seemingly weather dependent (worse in rain or high humidity) and I never experienced the hum (only the receiving of the radio station via a stethescope) and never did find a way to attenuate it.

    Now your house probably only has a handful of metal parts that could resonate. I'd start with ductwork: see if you can stick rubber grommets between ducts and supports. This could attenuate vibration. We also experimented with grounding the window frames to absorb any induced current, but didn't have success - but that may be because there was just too much metal receiving too much radio.
  7. Feb 4, 2009 #6


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    Last edited: Feb 4, 2009
  8. Feb 4, 2009 #7


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    Could the wind be causing a something on the outside of your home to vibrate at this frequency?
  9. Feb 4, 2009 #8
    Are your neighbors experiencing anything like this?
  10. Feb 4, 2009 #9
    Do you have an electrical transformer nearby? Do the electrical lines to your home run through a conduit from the transformer to the house?
  11. Feb 4, 2009 #10
  12. Feb 4, 2009 #11
    usually when i hear a sound in the night like that, it's the icemaker.
  13. Feb 4, 2009 #12
    So I need to get me a stethescope huh? I gotta run, will check out the links tomorrow. Looks like Edward found some good links, thanks all! Be back tomorrow.
  14. Feb 5, 2009 #13
    Okay, I have finally had time to read the links provided. So the answer to the universe is 42, and it is played in the key of b flat? I would love to delve deeper in to b flat if anyone wants to. Sounds like an interesting phenomenon.

    But a correction first. I goofed and was thinking A440 was below middle C, so the correct Hz is actually 466 - 494 Hz. My bad.

    Now attempting in order (hope I don't miss anyone)

    Russ, with VLF transmitting that low, is it possible that my house could be resonating or creating a harmonic at that frequency? That would be interesting if I was hearing when a submarine was in the sound. I know they go to Bremerton. Wow, if I made that public that I could hear subs, the Navy would be at my doorstep in a heartbeat!

    dlgoff, its possible, but there was no wind yesterday morning.

    Flat - I haven't talked to my neighbors yet, and I don't know anyone that is up at that time in the morning. I wish I wasn't myself!

    Edward, those were fun links! See my first paragraph today. Whats so freaking special about b flat? i would love to know if this occurs in other notes, or just (apparently) b flat. I couldn't find anything else.

    Proton, your ice maker comment made my daughter tell me a funny ice maker story, but we will share that some other time over a beer. ;)
  15. Feb 6, 2009 #14
  16. Feb 6, 2009 #15
    A few more: A generator running on a ship, the transformer in your furnace, your doorbell transformer, a leaking toilet valve, water running outside of the house such as when a sprinkler comes on.

    I am not sure about the frquency on the above.
  17. Feb 6, 2009 #16

    This is getting even stranger than I first thought.:eek:
  18. Feb 7, 2009 #17
    Mr Music have you checked the musical instruments in your house?There could be a frequency matching from an external source setting one of the strings or whatever into forced vibrations at or close to resonance.I can play the kazoo.
  19. Feb 7, 2009 #18


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    Somewhat unrelated; the image on my old CRT monitor suffers peculiar image distortion when an F# is played (particularly evident when listening to The Pyramid Song).
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