Hi everyone Newbie needs advice on how to record low frequency noise.

People I played with , we used them during recording, tuning, or just to look at the pretty wave from the synthesizer on the screen. they help to find and isolate noises.

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I rebuilt transmissions, not good with computer stuff . Cel phones today could have O scope apps. There might be software options. This will prove if there is something there or not regardless if they say they can 'hear' it.
 
There are measurement microphones that will measure down to 3 to 5 Hz, such as the Earthworks M23 and M30, but they aren't cheap. Figure to spend somewhere around £400 to £600 for the microphone. You can find them on Thomann's website. Many measurement mics only go to 20Hz, so if you REALLY want to measure subsonic, then it's going to cost to get the better ones.. You'll need an audio interface to hook the mic into your computer and record. Figure another £100. Set it up and record away, then you can analyze the recording to know if there is anything there.

You might consult with an environmental services company that does noise monitoring. They may have the equipment and for a fee would be happy to take measurements. Be sure to tell them it is for low frequency noise, as most noise measurements done for health and safety purposes involve simple noise measuring to make sure overall sound levels don't exceed government regulations.
 
You could also experiment to see if it's coming through the air, or through the structure. The old glass on the wall pressed up against your ear will let you know if it's structure born, but the the thing that is really important is that lower than 10Hz, which you can actually see is wind, not sound - so wavefronts that have real trouble being captures my smaller lighter diaphragms. The rate of change from + to - is too slow to accurately move the membrane, so they become very insensitive. Maybe you could attach a guitar piezo pickup to your wall - that might give you something.

Can I clear something up. Have you tried to record it and failed? One good trick we used in the reel to reel days was to record at 3 ¾ IPS, and then play it back at 15IPS - the two octave upshift often revealed low frequency noises and with modern DAWs, you could up it even more by fiddling with the sampling rates. the 6.5 could easily be got up to 50 or 100Hz with some doublings, and this might be very visible. The trouble is that recording it might be possible, but your system cannot reproduce it back?
 
Guy's thanks for advice this really is good advice, ive come to a placeand people know what they are talking about.
Yes i have tried recording it but play back was nothing...i have a down load of it which could put a link on to it on here..
The reason i snuck in to clear this matter up, was to see if the sound started or was not there when i was not in, make sense, AND LOW AND BEHOLD it wasn't there.

Soon as i was in after a hour sound started...

Look i'm not very tech minded, so some of the suggestions i need to do research on.. All i know is its low frequency below normal hearing, i can hear it other people can't and its very difficult to record.

Look guy's thanks i mean it.
 
Bones00 said:
My research on guitar piezo they don't go low frequency.
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They do if fed into a very high input resistance. You need something like 100,000,000 Ohms (100 meg Ohms) and that is easily doable with the common TL072 op amp but, such pre amps are not available 'off the shelf' so the only recourse is to make one or have one made.

BUT! We hit simple logic and economics. OP is "not technical" so the ONLY other option is to employ someone who is. Is the OP wealthy? I don't believe so...so, rock and hard place. WISH I could help but I am old, knackered and not there!

Sorry chap but some things we just cannot have. I for instance would love an electric car but cannot afford one by at least two orders of magnitude. I HAD planned to get some really good monitor speakers next year but the way cost of living is going in UK, not likely (I had planned to go into about $3000 of card debt but dare not do that for the foreseeable)

Dave.
 
Have you got a local university or college who do geological courses? Maybe they have seismographs or other equipment that were optimised for those frequencies?
 
Bones00 said:
The reason i snuck in to clear this matter up, was to see if the sound started or was not there when i was not in, make sense, AND LOW AND BEHOLD it wasn't there.

Soon as i was in after a hour sound started...
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You snuck in. ..Ok.

It was quiet. Then what happened after an hour? What you gave your position away to the enemy? Don't tell me you turned on the lights..Thats a rookie mistake.
 
sure its no air lock, speak against the wall, trust me. ok. i will try some of your suggestions though.
 
I've tried a speaker up against the wall with 6.5Hz - nothing, as just wind coming out of it, gentle wind too. I increased it to where I could feel the sub actually vibrating and it was 22Hz before the first physical event could be felt. Unless he really has got subs that can do this, then it's going to be louder in his house than yours.
 
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