Recording the sound of your clocks beat
The above screen shot shows the volume of each beat, along with any other sounds that the mechanism makes as it ticks away. For reference, since the horizontal scale on this plot is time, the difference between subsequent peaks reflects the duration of the beat. In this case, one beat (I labeled it the “Tick”) is longer than the next (the “Tock”). Please realize, I use tick and tock interchangeably, in as much as I am not focused on describing which is associated with the entrance or exit pallet.
What would cause different sound levels in a tick or tock? Two things: Variations in the power being delivered to the escape wheel and differences in the drop of the escape-wheel tooth. Differences in drop can be due to the escapement not being properly depthed (as in the drop is wider on one side than the other) or due to bent escape-wheel teeth. NOTE – bent escape wheel teeth will not impact the beat of a clock as much as variations in the length of the teeth.
It is interesting to note that the louder beats on the right-hand side of the plot occur every 4 beats: I suspect this is because the power transmitted to the escape wheel goes through a maximum when an escape-wheel pinion leaf is in its optimum position relative to the tooth of the wheel driving the pinion. Given there are 30 escape-wheel teeth, and the pinion has 8 teeth, one would expect the maximum force to occur once every roughly 4 beats. Of course, as the escape wheel turns, there will be times then the maximum force doesn’t align exactly with a beat, hence the fact that not every 4 beats shows a maximum.
Delving a little deeper I note that there seems to be quite a bit of “noise” just before these louder beats – I suspect this is related to the sound of the escape-wheel tooth sliding down the impulse face of the pallets. When I have a mechanism hooked up to a beat amplifier I can hear what sounds like a sliding sound just before the beat – I believe this plot shows a visual representation of this sound.
While this plot suggests that the tick and tock are about the same volume when not being impacted by the alignment of the pinion and driving wheel, it is not uncommon to find a mechanism that has one beat that is louder than the next – this is usually associated with uneven drop for the two pallets.