|MadSci Network: Physics|
As far as I can tell, the answer is no, sort of. If you use a pick to pluck a guitar string anywhere along its length, the frequency is the same. However, the timbre (tone quality) will be different depending on where you pluck the string, even though the frequency is the same. The timbre is created by the strengths of different frequencies in the overtone series, so yes, you can say that the pick affects those frequencies. But if by "resonant frequency" you mean the frequency you can hear (the string's given note name) or the physical resonance of the body/neck/etc. of the guitar, the answer is no.
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