Sound Waves

So, since we are studying different types of waves in Physics now, I decided to do a journal on sound waves. This past weekend my brother David had a cello recital at Punahou. While I was sitting there listening to the music, I realized that the way the cello makes noise is by the vibration that is created when you move the bow across the strings. Each note that comes out of the cello has a different frequency (number of waves per second). Also, when my brother puts more pressure on the bow, making the music louder, he is actually increasing the wave's amplitude. Similarly, if he decreases pressure on the bow, making the music softer, he is decreasing the wave's amplitude (height). I could just imagine all the waves that were flowing off of the tiny (well, not that tiny) instrument. I was amazed that I could understand at least some part of how music is created - since I am not a very good muscian at all - and it is all due to Physics class! Oh, and by the way, the picture I posted is not of my brother's performance at Punahou. He also recently performed at our church, so thats where the picture is from (in case you were confused since that stage doesn't look like Punahou).