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Dec 25 1906 Reginald Aubrey Fessenden transmitted the first ever voice radio broadcast.  
A Canadian-born electrical engineer and physicist, Reginald Aubrey Fessenden (1866-1932) transmitted the first voice message by radio. On Dec 25, 1906, ships on the Atlantic Ocean received his signal, transmitted from Brant Rock, MA. He employed a high frequency alternator rotating at 20,000 RPM to generate a 50-kilohertz carrier wave. Audio modulation was provided by a water-cooled carbon microphone attached in-line between the alternator output and the transmitting antenna.  
Fessenden had other significant radio inventions to his credit, including heterodyne radio reception, and the radio compass. He eventually held over 500 patents, including one for the invention of the sonic depth finder.  
Source: http://www.hammondmuseumofradio.org/fessenden-bio.html  
http://www.broadcasting-history.ca/stations/radio/ckx.html