art synonyms Sunglasses allow better vision in bright daylight, and may protect one's eyes against damage from high levels of ultraviolet light. Typical sunglasses are darkened for protection against bright light or glare; some specialized glasses are clear in dark or indoor conditions, but turn into sunglasses when in bright light. Most sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be ordered. Specialized glasses may be used for viewing specific visual information (such as stereoscopy) or 3D glasses for viewing three-dimensional movies. Sometimes glasses with no corrective power in the lenses are worn simply for aesthetic or fashion purposes. Even with glasses used for vision correction, a wide range of designs are available for fashion purposes, using plastic, wire, and other materials. The discovery that electromagnetic waves are capable of transmitting information sparked the invention of radio. The technology scaled like the old inventions in the telegraph as well as the telephone. According to some researchers, the amplitude modulation technique originated in the experimental and theoretical work of Leblanc, in 1886, Mayer (1875) and Rayleigh (1894). For example, the very first successful attempt to transmit audio signals over telephone lines happened inside mid-1870s and this may be called one of the first transmissions happening by using some type of amplitude modulation. The range of frequencies readily available for AM transmission comes from 535 to 1705 kilohertz. There is also the Frequency Modulation or FM technique, in which the frequency - instead of the amplitude - of the second signal is regulated based on the carrier wave. For a better understanding look at the comparison image. If you are seriously interested in work in music, whether it be singing in the band or playing a musical instrument, you have to create a professional demo CD in the recording studio. Making your individual demo on your hard drive won't being as professional or of fine audio quality as a more respected recording studio with greater equipment. The acoustics are better, the tools utilized is normally high tech, plus you've got the expertise of a producer or engineer to help you increase the audio quality of your respective demo.