THE MECHANICAL DEVICE
The mechanical device was conceived so as to guarantee objective repetitiveness of stimulation during sound recording. This device was conceived and created at the university "La Sapienza" in Rome, Italy, Faculty of engineering, under the direction of professor Enzo Marchetti of the Department of mechanics and aeronautics.
The device is furnished with a silent electric scaling engine with low speed rotation velocity, linked to a graduated metallic pole, and sets in motion a plectrum which pluckes the guitar string at constant impulse and velocity. The plectrum is perpendicular to the tested string, and placed at the proper height represented by a stop by a tangent screw .
The device has been designed so as to record and measure sound emission of the guitar soundboard in conditions as near as possible to those of human performance. The guitar is placed on a woollen-sponge cushion which isolates it from the bottom of the board of the mechanical device so as to avoid vibrations which would alterate acoustic parameters, and is kept firm by isolator thicknesses set so as to guarantee orthogonal levelling, measured by a spirit level.
To conclude, the tested guitar is isolated and has absolutely no contact with the mechanical device, except when the plectrum plucks the tested string.