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Old 19th April 2013, 05:22 PM   #1
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Location: Appleton, WI
Default Detecting subsonic car security setups

I have been spending sleepless nights now due to what I think is a subsonic car security system.

The car which has a decal on it which says "If this car is too loud, you are too old" is the suspected vehicle. It is a Mitsubishi tricked out with customizations and the loud car audio system is already heard and known.

This is an apartment complex and the original tenant did not have this boyfriend and so the problem is new but I did call the cops when the car first appeared and was playing loud.

Loud is not the issue here: I can feel something all through the apt when it is quiet. It disturbs my sleep and even maybe physically in the bowels. This sounds like some sort of paranoia except for the fact that after googling I saw that such devices may exist.

Is arming a car security device like this known by DIY audio?

And yes the low inaudible vibrations go on for hours-- indefinitely until the car is started and moved. This noise problem has been a kind of torture because it is so hard to detect and report to authorities if I have to.
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Old 19th April 2013, 06:08 PM   #2
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Do you have a link for this LF sonar car security system?
With so many alarm systems based on vibration sensors it seems like an unusual direction to engineer a new product technology.
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Old 19th April 2013, 06:25 PM   #3
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I seriously doubt this has anything to do with car security. The point of an alarm is to be extremely loud to alert the neighbourhood that something is wrong, not to be very hard to detect and make people in the general vicinity sick. This doesn't make any sense at all.

Detection should actually be very simple. Very low bass makes a lot of waves. Put your hand on the car and you should feel it very clearly. (Although I suspect there will be nothing to feel.)

Very low bass also takes a lot of power though, so if this is happening all night long every night you would expect him to have a dead battery every morning.

I'd suspect your neighbour's HT system, the building's ventilation system, and about a dozen other things (maybe even your own medications, health and wellbeing - do you notice any other symptoms lately?), but a car security system producing these symptoms doesn't make any sense.

Besides, if his system is really that loud that you need to be calling the cops, it's very likely that the reason it is loud is because it can't play low. It's probably vented and tuned at around 45 hz and probably has subsonic filters to make sure it doesn't have to play any real subsonic bass. That's how cars get loud.

Last edited by just a guy; 19th April 2013 at 06:28 PM.
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Old 19th April 2013, 07:34 PM   #4
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@Justaguy et all,

Thanks for the advice.

Last night at 2 AM the car rolled in and the noise started up after the guy clicked it closed. I put my clothes on, and went out to feel the car. Only the very slightest tremble and it could have been me in the cold.

I have not made any accusations on this until I know something. There was a big ice storm here last week. There may be utility trucks working all night on something. That is another possibility. While up at night I looked for sump pumps to be on, lights buzzing and other cars.

The coincidence of the vehicle and the noise is hard to escape. The car makes a lot of audio noise going to and fro in the lot.

It is not hum but more like a motor or very low speaker vibrations. I can feel it sitting here like a seat shaker might feel.
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Old 20th April 2013, 05:00 AM   #5
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Quote:
Originally Posted by just a guy View Post
Detection should actually be very simple. Very low bass makes a lot of waves. Put your hand on the car and you should feel it very clearly. (Although I suspect there will be nothing to feel.)

Very low bass also takes a lot of power though, so if this is happening all night long every night you would expect him to have a dead battery every morning.
Quote:
Originally Posted by loninappleton View Post
@Justaguy et all,
Only the very slightest tremble and it could have been me in the cold.
You have your answer. No matter how hard it is to ignore this car, it's not the car. The amount of power required to generate the subsonic frequencies would be VERY large. Most batteries would be "dead" in less than an hour. On top of the battery angle, the amount of force required to generate these frequencies would be very large. The metal body would not be slightly vibrating, it would be outright roiling under your hand. It would be vibrating like a power sander (possibly slight exaggeration but truthfully the vibration would be FAR from subtle). There is no way around these two facts. Likely, since you are still convinced in your previous reply, you will still want to consider the car. Remember, its impossible to prove a negative. Instead, you look at the evidence and decide at what point does the option stopping being probable and the what-ifs start becoming crazy-man land. I think you are at that point with the car being the cause.

This leaves you to investigating other options. These can be external things such as the machinery you mentioned (large equipment have a lot of power and can produce a lot of vibrations), your air-conditioning system (there maybe a resonance issues with the air-flow, kinda like when you open one window in a car, this is unlikely but not outside the realm of possibility). Then you MUST also consider the internal ones. The latter are the hardest because no one likes to admit to being influenced by the placebo affect. That being said we ALL are, there is a reason they have to test against it in medical trials. It's not because some people are too dumb to notice it, it's because anyone who can think is smart enough to induce it in themselves. Think about the number of times, you have felt creepy-crawlies (or spiders in the dark) on your skin because of something you saw on TV.
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Old 20th April 2013, 06:05 PM   #6
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I did talk to the guy who is my neighbor. He has all the gear but this problem wasn't it and he has been pretty respectful coming and going in the lot.

My suspicion is a refrigerator that has been running for days to cool down for a new tenant. But no opportunity to get the management co. to send their guy to turn it off to check. At least now it is cycling (if that's it) and I was able to sleep some.

Yes every wild thought goes through the head with such an unknown and the persistence of it over days. It's like a torture with no endpoint known.
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Old 20th April 2013, 07:27 PM   #7
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Geological prospectors use infrasonic shakers mounted on trucks.
It seems you experienced something like this: Infrasound - Wikipedia, the free encyclopedia
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Old 20th April 2013, 07:52 PM   #8
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Originally Posted by franzm View Post
Geological prospectors use infrasonic shakers mounted on trucks.
It seems you experienced something like this: Infrasound - Wikipedia, the free encyclopedia

If that were true they should certainly alert media and law enforcement plus the health department. This is an in-town second ring suburb. I saw no trucks during the shakeup. It may return for all I know.
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Old 20th April 2013, 08:19 PM   #9
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Quote:
Originally Posted by loninappleton View Post

Last night at 2 AM the car rolled in and the noise started up after the guy clicked it closed.
I don't want to be disrespectful or make assumptions here but this sounds a lot like anxiety disorder. This will cause a lot of the same symptoms as infrasound. You expect a problem and your brain creates it for you free of charge - uneasiness, nausea, disorientation, all that fun stuff. The only reason I suspect this as the most possible cause is because you associate these feeling SO strongly with the car in question even though the car is unlikely to have anything to do with it.

Quote:
My suspicion is a refrigerator that has been running for days to cool down for a new tenant.
Again, extremely unlikely. Making this kind of sound requires a ton of power or a very strong resonance (like long ducts). It's theoretically possible, I suppose, if the fridge was obscenely defective and producing a relatively loud 20 hz sound and it was directly in front of a duct that was at least 15 feet long, with the duct leading directly from that apt to yours and open on both ends. So theoretically possible maybe, but exceedingly unlikely.

The only things that have produced any type of infrabass that was even noticable in my house have been large trucks on the road and helicopters (not regular helicopters, but the large military style monstrosities that pass once or twice a year). I've got a fridge and 2 freezers (and I know what they sound like when they start to fail), HVAC system, and all that stuff and like most people I don't have any problems with any of it.

Anyway, make sure to record the time (start and end time) and date of these occurances so if you find a possible cause (like construction events or something else) in the future you can check your records to see if they match.

Last edited by just a guy; 20th April 2013 at 08:22 PM.
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Old 20th April 2013, 08:32 PM   #10
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The process of unknowing is very hard to cope with. I acknowledge that readily. Today my next door neighbor had some throbbing and thrumming low freq. noise coming my way. I went over to tell her to turn down the volume. No stereo was on just tv which I never hear from there. So I went down the hall. The sound became less. I returned and listened across the hall (where "the car" lives.) not as noticeable as at her door.

We then agreed that for a moment she'd turn off the dish washer. That was it. Once I knew what it was I knew and could accept the sound knowing it would end soon.

I never use the dishwasher-- never had it on after years. I live alone and so do dishes by hand never wanting to mess with it.

I include this anecdote because it might help others with similar situations.
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