To record infrasonic sound in the presence of ultrasonic sound.


I am planning to build something. For that I need to able be to record the sound less than 200 Hz, however sounds with higher frequency are present. Is there a method to avoid high frequency sounds from being recorded? Or a device that is able to do so ?


Posted 2017-10-21T11:47:10.310

Reputation: 21

Hi Aamir. I think you are using the wrong terms here- It is generally accepted that humans can perceive sounds lower(and higher) than 200 Hz, so infra/ultra doesn't really make sense here. What frequencies are you attempting to record? The mic doesn't seem to be the problem for you, so why can't you just remove the higher frequencies from the recording? I think more info is needed. – Marc W – 2017-10-27T13:41:19.357



Generally speaking, almost any transducer that can pick up infrasound will have almost zero response to ultrasound anyway, so this is unlikely to cause you any problems.

200Hz is not considered infrasound, so depending on what frequencies you want, a normal microphone may be suitable. Down below 20Hz it gets more difficult, so you will need to look at specialised tools. This site shows an example for seismic detection.

But in general, what is used is a low pass filter. This example from Audacity has a cutoff at 250Hz. And Audacity is in fact a useful tool to do this, rather than worry about building a filter yourself.

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Rory Alsop

Posted 2017-10-21T11:47:10.310

Reputation: 5 762


As long as the mic you are using can pick up the frequency you are looking for, a low pass filter should filter out the high frequencies. The amount of impact depends on the filter.

AJ Henderson

Posted 2017-10-21T11:47:10.310

Reputation: 7 961