The first sync sound experience I had in animation was to animate a water splash. Back in the day, sound was on 1/4 tape and you had to record this master take unto a roll of perforated 16mm Magnetic film.Once the sound was on the 16mm mag stock, you had to add a head and tail leader. I shutter to remember those days myself, but I learned how to read the sound and figuring out when the splash occurred and when the second droplet of water fell.
No Animateducated website or Youtube references to learn from; my only source was the Disney " Illusion of Life" book and still photographs that I could find in books about science high speed photography. Once the splash was animated and pencil tested, I had to sync it up to the mag stock of the splash sound effect. I will spare you the gruesome details, but let's just say when that drawing of a ball hit the water and the sound of the splash happened at the same time as my animation, that was pure magic to me.
So, here's a sequence with sound effects added to my animation again, but using the tools of today. When it works, I am still amazed.