Human Ears Also Create Sounds of Their Own

New studies on the human ear have recently revealed the fact that not only are we able to hear things around us, but that our ears also produce an acoustic signal, which is too faint to be picked up without the help of some serious modern-age technology. Highly sensitive microphones have been able to detect that each pair of human ears emits a certain type of sound, which is similar to a print, in that it can only be produced by one person. This find could lead to the development of biometric sensors to prevent identity theft and fraud, and could potentially save millions of dollars in stolen money from banks.

The newly found sounds that the ear generates have been designated as otoacoustic emissions (OAE), and originate, according to scientists, in the spiral-shaped cochlea in the inner ear. The cause of these emissions stands most likely in the tiny strands of hair that grow on its exterior. These hairs play a crucial role in hearing, as they are the ones that capture sound waves and then convert them into electrical impulses.

These currents then travel to the brain, where they create the auditory sensation. When they brush up to the cochlea, they generate small-intensity, nearly inaudible noises, which can only be picked up by very sensitive receivers.

At this point, some experts are working on a method to integrate this innovation in standard bank security measures, as for instance to protect against someone who has just stolen another person's identity and now calls to transfer the victim's money to their own bank account. In the future, security measures could be reduced to the bank clerk simply pressing a button when you call, which will generate a series of inaudible clicks. Depending on the ear's response, the machine will determine if the person calling is the “real deal,” or if he or she is just a crook.

“Hearing is an active process – the ear actually puts energy into the incoming sound waves to replace energy lost as sound is absorbed by the ear's structure. This process helps us hear things we otherwise would not, but as a result some of the energy added by the hair cells escapes as OAEs,” University of Southampton engineer and leader of the research, Stephen Beeby, is quoted as saying by NewScientist.

“Anecdotally, audiologists say they can tell different people apart – men, women, even people of different ethnic origins – by the profile of the widely varying types of emissions the clicks evoke. In the controlled conditions of a lab, everybody's emissions are indeed different, but whether this is a practical way of telling people apart as a real-world biometric still needs a lot of work,” the expert adds. “It has to be able to reliably recognize people over long time periods. For example, a fingerprint taken from a 20-year-old is still valid when they are 60,” Beeby says of the challenges that lie ahead for the new class of biometric devices.