Looking at this page, history of sound waves, I would conclude that Fouriers work was a precondition for any abstract measurement.
Savart produced sound waves with a chosable frequency, but a comparison via a human ear and correction (tuning?) iterations were required, which I would consider as sort of an indirect or relative measurement. Similar other references for comparison existed earlier, but were not adjustable, like the tuning fork invented around 1711.
So I would be surprised, to find a measurement deserving that name in time of Bach.
Mechanical frequency meters can be imagined (stack of resonators with step-wise resonance frequency, measurement by checking which one vibrates most) but I have seen real world examples only for very small frequency ranges as for alternating current here and its not clear, how to adjust the principle to undirected and poorly selectable wave as sound.