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

B

Bones00

New member
Hi

I have a major problem, my neighbour is playing low frequency noise through the wall, i have had environmental health out with recording equipment and it does not pick it up.
The equipment was a cirrus CR171A nuisance noise recorder.. I now have a big problem as nobody believes me what is going on. The microphone went down to 6.5htz. So how come it never picked it up when i can hear it clearly.. i have rented the equipment myself and have one recording put tbh, it seemed the the noise was below or not strong enough to pick up the noise. Its very frustrating as this has been going on for some time now, any advise on how to record please. This need to be done cheaply...

btw i am not very techie with computers or sound equipment..
Regards Bones UK.
 
Sorry hi everyone please welcome me to the forum...I have joined hopefully to get some good advice and help please.
I'm just very stressed about what's going on.
 
Bones00 said:
Hi

I have a major problem, my neighbour is playing low frequency noise through the wall, i have had environmental health out with recording equipment and it does not pick it up.
The equipment was a cirrus CR171A nuisance noise recorder.. I now have a big problem as nobody believes me what is going on. The microphone went down to 6.5htz. So how come it never picked it up when i can hear it clearly.. i have rented the equipment myself and have one recording put tbh, it seemed the the noise was below or not strong enough to pick up the noise. Its very frustrating as this has been going on for some time now, any advise on how to record please. This need to be done cheaply...

btw i am not very techie with computers or sound equipment..
Regards Bones UK.
Click to expand...
I see one of these 'noise nuisance' posts over at soundonsound.com forum about once a month, the answer is always the same, there is little the private individual can do and you must just keep banging on at Ev health dept until they sort it...or move.

I suspect the reason their gear did not pick up the noise is because their meter is "A weighted". This attenuates frequencies below about 200Hz (I will find the curves in a mo') by several dB and below 50 Hz it is WAAAAAY down and getting worse. "A weighting" is judged to give the best idea of the nuisance value of traffic noise to the human ear and traffic noise is almost 'white' noise, i.e. more of a hiss than a rumble.

You CAN buy a pretty cheap SPL meter with a C weighting (there are several apps for smart phones but see later) These should give a flat response down to 30Hz iirc. The MO is to set up the meter then VIDEO it with a phone and present that data.

https://www.noisemeters.co.uk/help/faq/frequency-weighting/ now going to look for a cheap C meter.https://cpc.farnell.com/tenma/ten01075/sound-level-meter-mini-c-type/dp/IN05466?mckv=s_dc|pcrid|490691434463|kword||match||plid||slid||product|IN05466|pgrid|49730280129|ptaid|aud-610668504919:pla-370500412984|&CMP=KNC-GUK-CPC-SHOPPING&s_kwcid=AL!5616!3!490691434463!!!network}!370500412984!&gclid=CjwKCAjwopWSBhB6EiwAjxmqDbxr6hYTi38uMeFt06ptBmAgt-rxH-7rccjUsEi4XeOhKs7FT2XjvBoCJAMQAvD_BwE

Dave.
 
thanks DAVE it is a nighmare as he turns it on when i try to sleep.
Please any more advice?
keep it coming.
 
Dave i looked and your link and the meter they used is there, but it did not pick it up and it was A and C weighted.
Any idea's
 
Bones00 said:
Dave i looked and your link and the meter they used is there, but it did not pick it up and it was A and C weighted.
Any idea's
Click to expand...
Ah but, did they have it switched to the C weighting. Could the people hear the noise? One trick to record VLF noise is to use a hi fi speaker as a microphone but this needs some technical knowledge to setup.

One problem is that the sound level that disturbs people trying to sleep (in near silence) is often too low to measure accurately with conventional SPL metering kit.

Dave.
 
A couple issues with this. It is highly unlikely you are hearing 6.5hz. Human hearing is around 20hz and above. It is sort of like infrared light being outside our ability to see. Also, you stated "playing". What is it he is playing that is able to reproduce 6.5hz? It is a guess, but I suspect you are hearing some sort of resonance from something in the structure. An overtone if you will. One would feel 6.5hz, not hear it. Cause? Unless you can add additional information on the "playing" aspect, could be something like a refrigerator compressor.

Also, as Dave indicated, it may be enough to bother you but below the threshold of where it would trigger any regulation.
 
My neighbour 400m away has a car with what sounds like no silencer. He leaves to walk the dog at 6.15 every morning. he returns at 6.40. He then goes to work at 6.50. My new neighbour thinks he probably chose the new house badly and wants to do something about it. Everyone on the route to the local park knows the noise. My son is a Police Officer - they've had loads of complaints, but the car has had a new MOT twice in the year, and passes - just. The snag is at 6-7am here it is silent and we can hear him all the way to the park. It wakes up probably hundreds of people, but looking at the sound meter on my phone, it's not, on the scale of the main road 100m away during the day, loud. It just wakes us all up.

No microphone goes down to 6Hz - you can see 6Hz but it's a pressure wave that is silent. It's pulsed wind, in effect. However - as it's capable of moving your ear drum, it can induce a very strange sensation but you cannot hear it. Electret microphones have extremely taut polarised membranes and they, at around 6-15mm in diameter don't have the physical ability to do much at all at that frequency. The actual wavelength of 6Hz is road map lengths - so the usual measuring devices don't work - a seismometer high! It's almost earthquake frequencies. I doubt any of us have anything that can detect it.

Where did you discover it was 6Hz? If we cannot measure it, who told you the figure? Maybe they were wrong. 6Hz is almost impossible to generate too.

What exactly is your neighbour doing? Are we talking about the thud thud of a kick drum, or something percussive? I doubt if music is the source that it's remotely that low - but it could be passing through structures. If you cannot get him to stop, you either haver to spend serious money, or move. Remember that if it can't be measured, it's probably not something you can offer to a court?
 
Hi rob thanks for reply, he is a very clever guy, who by the way is very computer and tech minded. I think he has some sort of speaker which emits a very low noise in which when i have had people round can not hear it, but i can. all i know its low very low i can feel my ear drum moving when hen turns the volume down or intensity. As for the 6hz i phoned cirrus research and they said the microphone can go down to 6.5hz. So why didn't it pick it up. He changes the sounds all the time from very bouncy sounds to long rumble sounds. I have had major problems about this problem. I come home from work nothing then once night comes its starts...When he knows someone in the house noise goes off. When they leave it starts again.. during lockdown i got hammered by the noise with know body to turn to. I don't understand why it does pick it up...I think is some kind of power full guitar speaker, but i'm not sure. As soon as he knows people are about i e, postman, police, environmental health workers noise goes. Even with the trojan 2 nuisance noise meter i'm told nothing picked up. I hired a CR171A noise meter from cirrus and i have one recording, but even with that i can't seem to play the sound back. As i set up the noise meter i hired i could hear the sound but the software graph on the meter wasn't bouncing to the sound the microphone even picked up my stomach rumbling, i saw the graph move but as for the low frequency sound nothing..I know the sound exists, ive been tested for titanus and i'm fine. The air goes very thick some times and i can feel the waves....I'm baffled. tbh..Thanks for response it is helping tbh. One enviromental officer who is susceptible to low frequency sound could hear a noise, but i ended ujp having an argument with him as he said the noise is coming from miles away. I said no, its only when i'm in the house i'm being targeted. I have snuck in a few times and heard nothing zipp. zero, then as soon as he knows im in bang the noise starts...Like a rumble very intense, very low.

Regards Chris
 
Bones00 said:
. I have snuck in a few times and heard nothing zipp. zero, then as soon as he knows im in bang the noise starts...Like a rumble very intense, very low.
Click to expand...
who would do that? are you the type that has some balls? Id go knock on his door and see whats up..
 
Ignoring the 6.5Hz for now, I'll begin by asking what part of the country you live in and what are your daytime and nighttime outside temperatures?

You and your neighbor share a wall.. are you in a townhome, rowhouse or apartment?
 
Bones00 said:
... when i have had people round can not hear it, but i can....the microphone can go down to 6.5hz.....He changes the sounds all the time from very bouncy sounds to long rumble sounds...When he knows someone in the house noise goes off. When they leave it starts again.. during lockdown i got hammered by the noise with know body to turn to. I don't understand why it does pick it up. I have snuck in a few times and heard nothing zipp. zero, then as soon as he knows im in bang the noise starts...Like a rumble very intense, very low.
Click to expand...
First thing - you nor anyone else can hear 6hz - nothing except a highly specialized repro system can reproduce 6hz - and it is not likely he has the gear - let alone just to annoy you. The fact that only you can hear it? - I don't know what to say but perhaps you should get some therapy - seriously - if you believe he is really torturing only you go knock on his door - ask him if he's playing anything and then if he is ask him if he could stop - more likely there is a train of some industrial process near you and it starts at night - but I go back to if you are the only one hearing it - I'm sorry but that is highly suspect.
 
Papanate said:
First thing - you nor anyone else can hear 6hz - nothing except a highly specialized repro system can reproduce 6hz - and it is not likely he has the gear -
Click to expand...

They have these rigs you wear on your chest. That low hz is more felt than heard. The 'speaker' looks like a vest you wear.

Screenshot 2022-04-01 060524.jpg
For those that like their sternum vibrated.
 
To put this in a bit of perspective. The Earthworks Measurement mic goes down to 3Hz. My interface when I tested it while setting it up to measure the studio acoustics does pretty well in low frequencies doing a loop test.

Here is the graph for the interface. It is only down 2.4db at 2Hz and less than half a db at 6.5Hz.

Soundcard-Cal.jpg


Now for the reality of play back. I have a 15inch Tannoy sub that can shake the room. Here is the response graph in the room prior to treatment. No where near the legendary brown note territory. Measurement mic or interface wasn't an issue. Just the limitation of the sub. OP should find out if his neighbor has a back to the future Doc Brown speaker in his flat cause even an 18 inch isn't going to do what he claims regardless of how computer savvy his neighbor is.

Sub.jpg
 
A speaker isn't the only way to produce a 6.5 Hz sound wave. If I had to do it, I'd use a motor spinning an off-center weight, and I'd mount it to a wall or floor with the motor shaft parallel to the surface.
 
You must log in or register to reply here.
Back
Top