BACKGROUND: The mini-microphones in cell phones and other communications equipment may soon be replaced with non-acoustic sensors that detect speech without actual sound, so that speech can be heard above loud background noise.
HOW IT WORKS: The tuned electromagnetic resonator collar (TERC) uses sensing techniques developed for magnetic resonance imaging, or MRI. The collar acts like a large capacitor -- an electronic device that can be charged to hold electricity. As a person speaks, the vocal cords vibrate, and the collar translates the movement into an electrical signal. The signal is processed by computer microchips and then synthesized into human speech.
ADVANTAGES: Non-acoustical sensors like TERC pick up only the sound of the person wearing the device. Conventional microphones pick up not just the speaker's voice, but also every other sound within its range, so there is a lot more background noise.
USES: Divers working underwater, crews in noisy vehicles, or soldiers on covert missions will use the sensors first. The technology is perfect for factory or constructor workers who must wear helmets for safety. But one day such sensors may allow people to use cell phones in places such as trains, theaters or libraries without disturbing those around them.
ABOUT SOUND: Sound occurs when a vibrating object, such as a ringing bell, sends a pressure wave through the atmosphere. This moves the air particles around it, which in turn move the air particles around them, spreading the vibration through the air in a wave that ripples outward. Dropping a pebble into a calm pool of water will have a similar effect. Just like light waves, sound waves have their own spectrum of frequencies, known as pitch. A higher wave frequency means that the air pressure is vibrating faster per second and the ear hears this as a higher pitch. With lower frequencies, there are fewer vibrations per second, and the pitch is lower. Unlike light, sound can't travel in a vacuum. Objects can only produce sound when they vibrate in matter.
IEEE-USA contributed to the information contained in the TV portion of this report.