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hearing aid

(Encyclopedia)hearing aid, device used in some forms of deafness to amplify sound before it reaches the auditory organs. Modern hearing aids are electronic. They contain a tiny receiver and a transistor amplifier, ...

Tesla, Nikola

(Encyclopedia)Tesla, Nikola tĕsˈlə [key], 1856–1943, American electrician and inventor, b. Croatia (then an Austrian province). An ethnic Serb, he immigrated to the United States in 1884, worked for a short pe...

control systems

(Encyclopedia)control systems, combinations of components (electrical, mechanical, thermal, or hydraulic) that act together to maintain actual system performance close to a desired set of performance specifications...

Glauber, Roy Jay

(Encyclopedia)Glauber, Roy Jay, 1925–2018, American physicist, b. New York City, Ph.D. Harvard, 1949. From 1952 he was on the faculty at Harvard, where he became a professor in 1956. Glauber was the co-recipient,...

tone

(Encyclopedia)tone. In music, a tone is distinguished from noise by its definite pitch, caused by the regularity of the vibrations which produce it. Any tone possesses the attributes of pitch, intensity, and qualit...

Wovoka

(Encyclopedia)Wovoka wōvōˈkə [key], c.1858–1932, Paiute, prophet of a messianic religion sometimes called the Ghost Dance religion. Also known as Jack Wilson, he was influenced by his father (a mystic) as wel...

Doppler effect

(Encyclopedia)Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is nam...

infrared radiation

(Encyclopedia)infrared radiation, electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm). Infrared rays thus occupy that part of the electrom...

Federal Communications Commission

(Encyclopedia)Federal Communications Commission (FCC), independent executive agency of the U.S. government established in 1934 to regulate interstate and foreign communications in the public interest. The FCC is co...

mixer

(Encyclopedia)mixer, either of two electronic devices in which two or more signals are combined. In the type of mixer used in radio receivers, radar receivers, and similar systems, a signal is translated upward or ...