Harmonics/Partials

[Dave M]

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I was set up for some tap testing into Visual Analyser so in a somewhat casual way looked at some single note spectra. While we rather glibly talk about upper partials shaping the sound of notes it is still a bit of a surprise to see just how many there are and how strong they remain right out to 2000 hertz or so. This is the open bottom E string:

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And also how the fundamental is the small peak not the largest as you might expect. And this is just one note. It's no wonder it's all so complicated.

[kiwigeo]

Frustrating when you're working on intonation of an instrument and VA won't latch on to a string fundamental. Some classical strings are notorious for this.

[Trevor Gore]

"Normal" plucking is usually around the sound hole area, which is at 1/4 string length. This gives a strong excitation to the second partial and so it often appears stronger than the fundamental. Tuners of all sorts will trigger on the highest peak and will switch peaks if the highest decays faster than the others. That accounts for the step change in tuning that some tuners show through the duration of a note. Try plucking over the 12th fret if you want to see more of the fundamental.

If you want to pick up on a particular partial, G-Tune allows you to "bracket" the trigger zone using left and right cursors in the spectrum view. The peak doing the triggering is then shown with a red X over it.

AP tuner with the harmonics graph open (View menu) will show you how all the partials vary in frequency over time.

Makes you wonder what "in tune" actually means.

[Dave M]

Trevor yes it certainly does. It was in the context of reading all about nut intonation (again) that I chose to look at this. And I only have to look at my inexpert left hand fingers to just see all the pushing and stretching as I try to get to the notes!

Thanks for the tips about tuners. I have noticed this behaviour.