Credit: Courtesy of William Saidel

Rutgers–Camden researchers, left to right, William Saidel, Dawei Hong, and Joseph Martin, have produced a mathematical theory that accounts for or explains all observed situations where noise actually increases the ability to hear.

Can’t hear? Turn up the white noise, says a team of Rutgers–Camden professors who have produced a mathematical explanation for the benefits of noise. Their findings could lead to major improvements in hearing-aid technology.

Dawei Hong, a computer scientist, and biologists Joseph Martin and William Saidel are using mathematics to explain the biological benefits of noise.

The Rutgers–Camden team’s breakthrough mathematical theory is comprehensive, explaining or accounting for all observed situations where noise actually increases the ability to hear. To develop the theory – actually a mathematical expression like E=mc² – Hong and his colleagues employed a variation on the wavelet technique, a standard method used in cleaning up digital images. The scientists’ discovery could have numerous applications – most obviously in treating hearing loss by artificially increasing the amount of noise in the cochlea of the inner ear, perhaps by an implanted device.

Although the Camden research team studied noise in the auditory system, for example “white noise” or “noise-in-the-channel,” noise also can refer to other random phenomena in biological systems and the natural world where it may be a fundamental feature.

The team applied this principle of noise to a process called “quorum sensing” in bacteria. How bacteria signal one another to coordinate certain behavior and act collectively – such as when causing an infection – may be based on “noise” in the cellular environment.

The researchers used bacteria as a starting point for observing how noise affects cell-to-cell communication. A full understanding of how this simple form of communication works might show how to disrupt it, and the resulting infection. The team will next apply their idea to the nervous system, where the cell’s entire job is to communicate.

The dotted line represents the threshold for detecting a signal. The top graphic shows a low amplitude signal (blue) and low noise (green). The middle panel shows two types of signals that have had noise added. The red one doesn’t reach the threshold while the blue/green signal crosses the threshold but is too noisy to be intelligible. The bottom panel illustrates the result of applying the new three-step mathematical approach to a signal combined with noise, giving a "denoised" signal that both crosses the threshold and is understandable.