These are holographies taken in ENEA laboratories in the following way:

Trigger >electromagnet pulse >release of a teflon weight from a predetermined distance> weight contact with a rotating lever which enables the plectrum to pluck the string > two photograms taken in refracted laser light in a sequence of a millionth of second one from the other, after a predetermined half a second, one second, one second and a half, two seconds and a half, four seconds lapse.

PHOTOS OF ENEA LABORATORIES
H O M E
Already after two seconds and a half the activity of the soundboard of the traditional guitar appears nearly inexistent; after four seconds it stops, while vibration continues on the Greci guitar.
power = 40 cm
"medium strenght" plectrum
E = first string

comparison between "Greci" guitar and Ramirez 1st class guitar