Yes, you could get a reasonable idea what people were plotting on our Benson(s) from the sound. Many yards of spectra we plotted, even before Versatec matrix plotters came along.
When we got an A4 flatbed plotter (early-ish 80s), I remember using it to produce the first computer-generated overhead slides anyone in the group had seen, but it was also useful in reverse for digitizing plots from papers by moving the pen and recording points.
I came here to post exactly this. Not forgetting the almost musical accompaniment of the stepper motors.
Just as well really, as they weren't exactly fast.