Back in 2001, the nanotechnologist Jim Gimzewski learned something interesting: When living heart cells are put in a petri dish with appropriate nutrients, they continue to beat. He started wondering if all cells might similarly pulsate -- and if so, would they make noise? After all, sound is nothing more than vibrations travelling through the air.

So Gimzewski decided to find out -- by building the tiniest amplifier on the planet. He took an "atomic force microscope", a device so precise it can measure the bumps on the outside of a cell's wall. Then he held it lightly against the membrane of a yeast cell, so that like a record needle, it would record any movement and translate it into sound.

The result? The cell wall rises and lowers a distance of three nanometers -- about 15 carbon atoms stacked up -- 1,000 times a second. When you amp that up to the level of human audibility, according to a report in the Smithstonian Magazine, here's what you get:

The frequency of the yeast cells the researchers tested has always been in the same high range, "about a C-sharp to D above middle C in terms of music," says Pelling. Sprinkling alcohol on a yeast cell to kill it raises the pitch, while dead cells give off a low, rumbling sound that Gimzewski says is probably the result of random atomic motions. The pair also found that yeast cells with genetic mutations make a slightly different sound than normal yeast cells; that insight has encouraged the hope that the technique might eventually be applied to diagnosing diseases such as cancer, which is believed to originate with changes in the genetic makeup of cells. The researchers have begun to test different kinds of mammalian cells, including bone cells, which have a lower pitch than yeast cells. The researchers don't know why.

Gimzewski calls his new science "sonocytology," though he freely admits he's not sure whether the cells are really making the noise; they could be absorbing vibrations from elsewhere, including the microscope itself. But if it's true that cells make distinct sounds, this could be a weird -- and neat -- new diagnostic tool.