Every note played on an instrument, or even sung, is actually a composite sound consisting of approximately 32 overtones. On stringed instruments, these overtones can be isolated using harmonics. Sympathetic vibration occurs when the overtones of an executed note overlap with the overtones of an open string. Harmonic nodes, as the overtones are called in string geography, respond to similar frequencies, and vibrate the open string audibly, and sometimes even visually.
Select an instrument to calculate its most resonant keys and most resonant notes:
Select the tonic, scale quality, and instrument to find the most resonant notes in the key.
Select a note and an instrument to calculate the sympathetic frequencies on each string.