I was experimenting with sound analysis lately and from what I see when I plot spectral data of an audio file is that apart from notes that were actually plucked there are some other notes with quite high local amplitude.
For example I have a sample where D major chord is played with some nasty distortion. After looking onto the spectral plot I can observe a note D, F# and A as expected. But as I go higher some other notes have higher amplitude than threshold, one of those is E.
So, the question is: is it a normal thing that when I play D major the note E could be observed on a spectral plot but not heard or that's just error during recording ?
- that is not a DC component
- audio is in high quality, therefore there are almost no background noise
- the note E has some harmonics further in spectrum