How does the large central vacuole in plants maintain homeostasis?

Maintaining acidity- In case the pH in the environment drops a lot (becomes very acidic), there is a flux of H ions from the cell's cytoplasm into the cell's vacuole thereby increasing acidity to required level and thus maintaining the specific pH in the cells internal environment as well.

Turgidity- Vacuoles regulate the turgidity by regulating the amount of water inside the cell. 
cell has excessive water: vacuole absorbs the water and then diffuses it out of the cell.
cell lacks water: water from the vacuole gets passed back into the cell thereby maintaining turgidity. 

And here's a video https://youtu.be/3tqjITi8S8s

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.