How to measure constant low frequency tone?

[Tom32]

Hi,

I would like to know how I can measure a low, constant “hum” coming from a heatpump with a laptop ?

Can someone please tell me how I can do this?
Do I need specific hardware. What screens or functions of audacity do I need?

Kind regards,
Tom

[Trebor]

Can record and display sound in Audacity …

https://manual.audacityteam.org/man/multi_view.html

but such recordings are not proof of how loud the sound is.

There may be law regulating the maximum sound permitted in your home by your neighbors heat pump, need (trained person with) a calibrated sound meter to measure it.
[ Environmental health department ? ].
I don’t think the cheap sound-level (decibel) meters on Amazon would stand up in court.

[Tom32]

Hi,

Thank you for the help.

When i record i get this:

The sound i am trying to record is not loud, but a monotous tone like under an electrical powerline, but i guess i should see something ?

Does this mean my microphone is not good enough ?
I am using a miniDSP Umik-1 microphone.

[DVDdoug]

Yeah, Audacity isn’t calibrated… There is no known calibration between dB SPL levels (acoustic) and dBFS levels (digital).

Although, with a calibrated USB mic (like you have) you could make a calibration. It might even be included in the specifications for the Mic.

@Tom32

but i guess i should see something ?

Try the Amplify effect. The display doesn’t have nearly the resolution of your hearing and quiet-sounds don’t show-up well (If they show-up at all).

And maybe a low-pass filter to remove the higher frequencies that you don’t care about.

I am using a miniDSP Umik-1 microphone.

You might try REW (FREE). It can use the calibration file supplied with your microphone to get an accurate SPL measurement, and it can show a corrected/calibrated spectrum. (I don’t have a calibrated mic and I’ve never actually used it.)

[Trebor]

@Tom32

Does this mean my microphone is not good enough ?
I am using a miniDSP Umik-1 microphone.

If the mic records you speaking, but flatlines when you are quiet, there may be an “audio enhancement” called a noise-gate which stopping you recording comparatively quiet sounds.

https://support.microsoft.com/en-us/topic/disable-audio-enhancements

[Tom32]

Ah, im gonna try the amplify and low pass suggestions.

REW: what is the diagram that would show me the most information ?
I have to read the tutorial to use it. a LOT of options
( or is measuring what i want not so difficult ? )

I measured this, but i have no idea what i am reading:

thank you!

[Tom32]

Thank you very much for the suggestion. I will try this tomorrow.

[Tom32]

i tried measuring a second time with audacity and this time i got this when analyzing a small part of a larger recording:

[Trebor]

NB: microphone recordings often include mains hum at 50Hz/60Hz, This deep hum is picked up electrically, (like an antenna), not acoustically, (not audible in the room).