The 'F' is Fundamental! (the why of shapes)
Why are f-holes shaped like that?
Some scientists recently wondered why the shape of the ‘F holes’ had evolved so much over time, from being a single hole, to a curved ‘c’ shape and now an ‘f’! The f-shape turns out to have physics that push a lot more air than a circular hole, making the violin’s output dramatically more powerful compared to the use of one simple hole. Over centuries, sound hole perimeter length gradually grew, providing greater conductance, greater air volume and mass flow rates over time, resulting in a richer sound quality and tone being produced.
— Niamh Clark (S5)