A device that eliminates cellphone background noise - even from a soccer stadium or wedding hall - has been developed by researchers at Haifa's Technion-Israel Institute of Technology. The optical microphone eliminates distracting noises by monitoring acoustic signals from the human head. Prof. Motti Segev of the physics faculty, together with Zvi Katz and Dr. Rami Aharoni, have registered a patent on the device, and three patents have been applied for in the US. "The basic concept of the microphone, which is called ONFM," is based on the optical identification of acoustic changes in the skull or other parts of the body while the user is speaking," Segev said. "When we speak, we hear ourselves from the transfer of sound waves in the bones of the head. The ability to identify these tiny acoustical changes in the skull makes possible the differentiation between the voice of the caller - the signal that interests us - and the background noises that come from outside the body." On the basis of this differentiation, Segev said, one can filter out the background noises much more successfully than with existing noise filters. A working model showed that it filtered out almost all background noises, leaving only one per 1,000. In principle, the inventors said, it can be improved even more. The microphone also eliminates sudden noises that cannot be filtered out by systems based on computer programs. Applications for two of the patents have been filed for operating a device a few millimeters from the user's mouth and for a device that can remain several meters away. The remote-control device makes possible additional applications, such as improving the use of hearing aids. The "revolutionary" microphone makes it much easier to understand the caller's words in a noisy environment, and since the surrounding sounds are not heard on the other end, the caller does not leave any hints about where he is. One could speak from home without a child's crying being heard, and sales agents could do business from a bustling cafe. It could also be used on the battlefield for communications, in factories, at sports events and even at wedding halls where the band is playing at a deafening volume.