[TriEmbed] Monitoring Environmental Sound

[Scott Hall]

You'll need a low-frequency microphone, like a bass drum or tympani mic,
but one designed for sustained sounds (the pickup should go down to 16 Hz
or so). You may also need to insert a preamp prior to sampling. There is a
good buildable circuit and mic recommendations in an issue of Elektor
Magazine from about 7 years ago - if I can find it on their archive DVD
I'll forward you a copy.

I can hear a sustained low-freq rumble near my house, but I've analyzed it
as coming from I-540 traffic travelling through the ground creating
interference patterns with high-power power lines near my house - a
subharmonic of the 60Hz power frequency, below C1 of a handbell. I've
looked up the geology of the area, and my house is along a buried
ridge-like feature that borders Wake and Durham counties, that in theory
could guide and amplify such a wave. The two cross each other near
Leesville Road, then the ground feature runs along there to right by my
house and beyond.

Scott G. Hall
Raleigh, NC, USA
scottghall1 at gmail.com
*Although kindness is rarely a job, no matter what you do it's always an
option.*

On Mon, Mar 24, 2025, 9:52 AM Rob Parsons via TriEmbed <
triembed at triembed.org> wrote:

> Hi All,
>
> A project...
>
> I have been interested in monitoring environmental sounds for quite a long
> time.
>
> Am I hearing "The Hum"?
> https://en.wikipedia.org/wiki/The_Hum
> My wife does not hear it.
>
> What is driving my dog crazy sometimes?
> (Dog hearing range is 40Hz - 60000Hz)
>
> What hidden sounds is my house generating?
>
> There are some ultrasonic microphones.
> https://batsound.com/
> <https://batsound.com/product-category/usbmicrophones/>
> https://www.dodotronic.com/product-category/usb-microphones/
>
> Some are very expensive.
> https://roga-instruments.com/ultrasonic-usb-mic/
>
> https://www.titley-scientific.com/product/omni-directional-ultrasonic-microphone/
>
> My 'Analog Discovery 2' has a spectrum analyzer feature. Been looking for
> a microphone or ultrasonic sensor that I could hook up to it.
>
> Anyone out there done any work in this area?
>
> Rob
>
>
>
>
>
>
>
>
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