# Plot Spectrum Export

Audacity 2.1.2, installed via zip, XP sp3

When I export from Plot Spectrum the txt file is a 2 column list no matter what I’ve tried.
Different lengths but always only 2 columns.

Frequency (Hz) Level (dB)
10.766602 -56.411316
21.533203 -49.801842
32.299805 -55.400322
43.066406 -69.009727
53.833008 -55.846722
64.599609 -52.403141
75.366211 -59.207691
86.132813 -77.578537
.
.
.

What I expected was a file I could import to excel and plot the curve.

The directions seem beyond simple but there is something I’m missing.
I’ve tried zooming, selection,different wav files, … ad nauseam
and I’m beginning to feel feeble minded.

Could someone please walk me through a (detailed) example.

There are only two axes on plot spectrum : frequency & level. So two columns of figures is all you’re going to get.

I don’t use Excel, I use Libre Office Calc, so I can’t give step by step details, but here’s a general outline.

Plot Spectrum export gives you what you need.
To make importing into a spreadsheet easier, delete the top line of the text file first so that you have only the data in the file:

10.766602 -56.411316
21.533203 -49.801842
32.299805 -55.400322
43.066406 -69.009727
53.833008 -55.846722
64.599609 -52.403141
75.366211 -59.207691
86.132813 -77.578537

To plot the frequency curve, you need two pieces of data for each point on the curve. You need to know the frequency (which “Plot Spectrum” plots on the X axis) and the amplitude (which “Plot Spectrum” plots on the Y axis).

In the text file, the first column contains the frequency data, and the second column contains the amplitude data (in dB).

Import settings:
You need to import the file, using ‘space’ as a field delimiter, the data as ‘numeric’, and ‘new line’ as a ‘column delimiter’.
This should give you two columns of numeric data, the same as is in the text file.

Technical note:
The amplitude values are relative to a 0 dBFS sine wave.
If you want to convert from dB to linear amplitude, the equation is:
linear = 10.0 ^ (dB / 20.0)

Help for Microsoft Excel: https://support.office.com/en-us/excel

I’m trying to do a noise analysis on a recording of patterned low frequency noise - 20Hz to 1000Hz
to find the repeating frequencies.
Did realize my error re the 2 columns after I posted.
I spliced some known frequency tones together, output and charted in Excel and got a better feel
for what I was seeing.
Per your posts I’m using the “plot spectrum” correctly with the default settings.
I’m trying enhanced autocorrelation.

Used to do dsp coding for NOAA but it was years and years ago and it’s coming
back too slowly.

Thanks for the help.