Author Topic: Sound of silence: What does a FFT of the "silence" in your area look like?dbtech  (Read 277 times)

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Offline Beamin

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It would be cool to see what back ground noise looks like in different areas. This is created using "db Meter" app (free app so others can try this) on an iPhone 7. I live out in a kind of rural area and wondered how quiet can things get. What I learned surprised me. Shutting off all noise sources in the house and closing modern sealed windows tight you cant get less then 30 db. Now the low frequency I expected to come through the walls so I'm not sure what the high frequency is unless its harmonics of the low frequency stuff. To my ear I can hear the stuff if I watch the graph but the most part I just hear ringing, which is what happens when I hear silence, granted my hearing only goes to 15k due to loud music as a kid (regretting that stupid car stereo I had now).

The low frequency stuff I'm not sure what it is but by taking this and watching it all night and day and measuring the peaks of the sounds and their harmonics that always accompany them you can start to guess what noises are what. The low frequency 80hz and 150hz is cars driving that are too far away for me to hear. Now if the car comes down the street you can tell by watching these peaks grow, you can tell a car is coming long before you hear it let alone see it. If there are helicopters or airplanes a similar thing happens but at slightly different frequencies.

It would be interesting to see what the silence looks like in the city country and different areas to figure out why its so noisy. I see why they make anechoic chambers now, silence is really noisy!

The night is MUCH quieter then the day. Insects and cars seem to make up most of the sound as well as far away lawn mowers, which are always interesting to watch on the graph.
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