Hi,
I am trying to do real time Spectrum Analysis of audio signals sub 20Hz. More specifically, like in the attached image instead of the track spectrogram that Audacity does.
I don’t think Audacity has that functionality (that type of graph in real time)?
I have a professional spectrum analyser but it does not go below 9KHz. What do people use in the audio industry? Are there some freeware software perhaps that takes the signal from the PC audio jack input?
Try Soundcard Scope. Click the “Frequency” tab for the spectrum analyzer. For low frequencies you can move the cursor to the left and then zoom-in.
It shows information below 20Hz, but FFT has resolution limits (that are more apparent at low frequencies) depending on the FFT size (number of samples) and sample rate. So I’m not sure about the accuracy/precision.
To view the spectrum of very low frequencies, resample the track to a low sample rate. Plot Spectrum displays the frequency range up to half the sample rate, so if you resample to say 100 Hz, then you will see a detailed view of the sub 50 Hz range.
Thank you @Trebor
yes, but instruments don’t have a sharp “90 degrees” cutoff slope. So even if it has a flat-ish response even to just 10Hz, down to 5Hz you would still get a pretty decent plot of frequencies present (although the amplitude obviously would not be 100% correct).
