- published: 02 Jul 2013
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Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.
Sound is a sequence of waves of pressure that propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation). During propagation, waves can be reflected, refracted, or attenuated by the medium.
The behavior of sound propagation is generally affected by three things:
When sound is moving through a medium that does not have constant physical properties, it may be refracted (either dispersed or focused).
The perception of sound in any organism is limited to a certain range of frequencies. For humans, hearing is normally limited to frequencies between about 20 Hz and 20,000 Hz (20 kHz), although these limits are not definite. The upper limit generally decreases with age. Other species have a different range of hearing. For example, dogs can perceive vibrations higher than 20 kHz, but are deaf to anything below 40 Hz. As a signal perceived by one of the major senses, sound is used by many species for detecting danger, navigation, predation, and communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds. Many species, such as frogs, birds, marine and terrestrial mammals, have also developed special organs to produce sound. In some species, these produce song and speech. Furthermore, humans have developed culture and technology (such as music, telephone and radio) that allows them to generate, record, transmit, and broadcast sound. The scientific study of human sound perception is known as psychoacoustics.
Elizabeth Warren (born June 22, 1949) is an American bankruptcy law expert, policy advocate, Harvard Law School professor, and Democratic Party candidate in the 2012 United States Senate election in Massachusetts. She has written several academic and popular books concerning the American economy and personal finance. She contributed to the oversight of the 2008 U.S. bailout program, and also led the conception and establishment of the Consumer Financial Protection Bureau.
Born in Oklahoma City, Oklahoma, Warren attended The George Washington University and the University of Houston. She received a J.D. from Rutgers School of Law–Newark in 1976. Warren taught law at several universities and was listed by the Association of American Law Schools as a minority law professor throughout the 1980s and 1990s. In the wake of the U.S. financial crisis, Warren served as chair of the Congressional Oversight Panel created to oversee the Troubled Assets Relief Program in 2008. She later served as Assistant to the President and Special Advisor to the Secretary of the Treasury for the Consumer Financial Protection Bureau under U.S. President Barack Obama.
Donald John Trump, Sr. (born June 14, 1946) is an American business magnate, television personality and author. He is the chairman and president of The Trump Organization and the founder of Trump Entertainment Resorts. Trump's extravagant lifestyle, outspoken manner and role on the NBC reality show The Apprentice have made him a well-known celebrity who was No. 17 on the 2011 Forbes Celebrity 100 list. He is well-known as a real-estate developer who amassed vast hotel, casino, and other real-estate properties, in the New York City area and around the world.
Trump is the son of Fred Trump, a wealthy New York City real-estate developer. He worked for his father's firm, Elizabeth Trump & Son, while attending the Wharton School of the University of Pennsylvania, and in 1968 officially joined the company. He was given control of the company in 1971 and renamed it The Trump Organization.
In 2010, Trump expressed an interest in becoming a candidate for President of the United States in the 2012 election. In May 2011, he announced he would not be a candidate, but a few weeks later he said he had not completely ruled out the possibility. In December 2011, Trump was suggested as a possible Vice Presidential selection by Michele Bachmann. Bachmann has since suspended her presidential campaign.
Actors: Quirino Cristiani (director), Pepe Iglesias (actor), Pepe Iglesias (actor), Pepe Iglesias (actor), Constancio Vigil (writer),
Genres: Animation, Short,