It is unknown who discovered sound. It is known that discoveries regarding sound and how it travels were made as far back as 1500 when Leonardi Da Vinci discovered sound traveled in waves.
In the 1600s, Martin Mersenne was the first to measure the speed of sound in the air. Over the next 100 years, many scientists made discoveries regarding different aspects of sound as humans understand it today. Some of the scientists were Galileo, Kircher, Newton and Boyle and Hook. They would discover ideas, such as the relation of pitch to frequency, consonance, dissonance, the speed of sound in gas and that sound does not multiply in a vacuum.