Let me revive this thread. I’d like to check if our piano (and other pianos) is tuned. I have tuner android application for the phone but it’s not very easy to use for the purpose (although given enough time task is feasible).
I’d like to record a files with all keys of the piano pressed after one another and then check that the sound had the necessary frequency .
Any recommendations how to do so? Looking at a test file I’m not sure which settings would produce best result. I’m having varying results and the frequency that should go on top don’t always appear strongest on the plot. Perhaps different settings for the different frequencies?
Look for the highest peak that is close to the expected frequency.
Set the “Size” parameter in “Plot Spectrum” to a high value (8192 should work well) and expand the Plot Spectrum window to full screen.
Hover your mouse directly below the peak that is close to the expected frequency and look at the “Peak” read-out just below the graph.
If there are two or three peaks very close together, that is because piano notes usually have 2 or 3 separate strings. Ideally all the strings for a particular note should be exactly in tune.
In this (badly recorded) piano note, the “expected frequency” is 523.25 Hz (“C” above “middle C”).
If you look closely you will see that there is a double peak (527 and 538 Hz) indicating that the piano is out of tune (sharp) and that the strings for “C” are not in tune with each other (a bad “honky-tonk” sound).
“Plot Spectrum” is not a very good way to tune an instrument as it is difficult to measure the frequency precisely enough. Hardware “chromatic” tuners are generally better.