Help recording low frequency sound

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TrickyNicky
Posts: 3
Joined: Sat Apr 01, 2017 4:15 pm

Help recording low frequency sound

Post by TrickyNicky » Sat Apr 01, 2017 4:36 pm

Hi everyone. I found this forum as I am looking for some help and wondered if you might have some ideas for me. Forgive me, I have no knowledge of electronics so these may be stupid questions. I have a young dog who is terrified of wind turbines. This is not a visual problem but seems to be related to a sound I cannot hear, maybe low frequency noise. The sound can travel many miles depending on the wind direction. If it is bad enough, she just runs off and heads for woodland where she clearly is less affected. She has a similar problem travelling in cars and I suspect it is again an engine sound she hears that I cannot. I have a few things I wish to try to help her.
1. I need to record the sound she hears (wind turbine and car noise) and play it back to her very quietly and over weeks, gradually increasing the volume to try and de-sensitize her. Any suggestions of how I can do this please?
2. I need something like a bat detector that changes the sound she hears into a sound I can hear so I know when she is being affected.
3. Would it be possible to cancel out the sound she hears using 'white noise'? Maybe using a CD in the car and develop something to she can wear on her collar or maybe earphones for when out walking.
I am conscious I am writing this on 1st April. This is not an April Fool. We have tried so many things to help her that have not worked so I am now looking 'outside the box' to come up with alternatives. I'm sure I am not the only person with a dog like this so the solutions could help others, not just me. If this is not the right place to post the query, perhaps someone could suggest a place I can go to get some answers. I am grateful for any help. Thank you.

David
Posts: 216
Joined: Sun Oct 04, 2015 6:18 pm

Re: Help recording low frequency sound

Post by David » Tue Apr 04, 2017 12:09 pm

Hello. I don't know much about dogs, but here goes on some things you mention.

If you want to record these very low frequency sounds, check the frequency responses of the microphones / recorders /amplifiers / speakers very carefully. It is usual (esp. in low-cost items) for the LF response to be reduced below (say) 100Hz to reduce mains hum and other intrusive noises.
I have not heard of any "reverse bat detectors", but would a straightforward noise meter - analogue or digital - work? Again look at the quoted LF response.
Noise cancelling headphones are available, but these are expensive, and made for humans! However might be worth an enquiry.

Hope this helps

TrickyNicky
Posts: 3
Joined: Sat Apr 01, 2017 4:15 pm

Re: Help recording low frequency sound

Post by TrickyNicky » Wed Apr 05, 2017 7:29 pm

Hi David. Thank you for taking the time to reply. This probably sounds daft but where do you buy microphones, recorders, speakers etc that can record LF sounds? Are there special websites or do I go to PC World? I have been advised to use the speaker on my phone but haven't had any success, maybe because of what you have mentioned. I don't actually know if it is LF sound so I like your idea of a noise meter first, to test my suspicions. Can you buy these/borrow one so I can find out? Noise cancelling headphones too. Where do you get them?
If possible I would like to find out more about wind turbines and the noises they give off. Do they give off sound even when not turning for example? Would anyone know where I might ask? A forum maybe?
Thanks very much.

David
Posts: 216
Joined: Sun Oct 04, 2015 6:18 pm

Re: Help recording low frequency sound

Post by David » Fri Apr 07, 2017 9:39 am

Hello.
Google is the Universal Guru for finding things. Search for "infra-sonic microphones / anything else". Professional equipment will be very expensive, but look on stormwise.com - there is a simple infra-sonic microphone which you can build at home. I doubt if PC World have anything of use for your particular project.
If you are going to buy anything, including noise-cancelling headphones, try Amazon first to see what they have. I am continually amazed at their range of goods.
Wind turbines are a very emotive subject to many people (for and against!) and I think you will have many hours researching their noise generating abilities, or lack thereof. Don't forget that anything which disrupts the free flow of wind houses, flagpoles, chimneys, virtually anything with a profile will produce noise of one form or another - but a lot will be in the infra-sonic region.
Let us know how you get on!

TrickyNicky
Posts: 3
Joined: Sat Apr 01, 2017 4:15 pm

Re: Help recording low frequency sound

Post by TrickyNicky » Fri Apr 07, 2017 9:54 am

Hi David. Thank you again for this helpful information. Just knowing what to search for is a big help to me. What do infrasonic microphones plug into? Does it need to be a special recording device or will an App on my computer do? (I'm not very techy)!)One other item I need to know more about is the noise meter you mentioned. Is that what it is called? Do they all measure different frequencies or just volume of noise? Any other names that I could search for? Do they all detect low frequency sound? Are they reasonably portable? It will take some detective work to find out what frequencies affect her but it would be a good start. Thanks again. Hope you don't mind all the questions but you are a godsend. I have been searching and asking these questions for months with no progress, so this is really fantastic for me. Of course I will update you on my progress, it is the least I can do.

David
Posts: 216
Joined: Sun Oct 04, 2015 6:18 pm

Re: Help recording low frequency sound

Post by David » Fri Apr 07, 2017 12:36 pm

Hello.
The different connections will probably differ from microphone to microphone - you will have to look at the specs. Commonly used ones are the mini jack plugs which will go into the mic input on your computer. You might be able to find some with USB plugs also. Search for "noise meters with USB output". Noise meters will have settings which effectively change the weighting of different frequencies to match different uses. Again, find out from the specifications. Experimentation will probably be needed!

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