Here are two videos that do a good job of describing how sound is produced.
Sound Waves and their Sources (1933) http://www.youtube.com/watch?v=cK2-6cgqgYA&list=UUucupwTXUP0IaKzafA-WmvA...
Pitch Systems in Tonal Music Part 2: The Octave and Just Intervals http://www.youtube.com/watch?v=3ZL5evNWD2M&feature=BFa&list=PLB322565F6E...
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After watching the BluesHarmonica.com overview video, try one of the lessons below to experience a lesson at BluesHarmonica.com.