Imagine you’re sitting at a pond, listening to the din of croaking frogs. You want to know how many frogs are in the pond, but you can’t pick out the individual croaks—only the combined sound rising and falling in volume as frogs start and stop communicating.

But what if you were able to examine these volume changes to figure out how many frogs are in the pond?

That’s the idea behind a new method developed by the Funke Lab at Janelia to count the individual molecules contained in a single spot of light detected by a fluorescence microscope—a quantity important for understanding the underlying biology of a living system. The paper is published in the journal Nano Letters.