Pitch is very important when it comes to sound. Pitch is how high or low the sound frequency is. Pitch and tone go hand in hand and especially when it comes to sound art and let me tell you why. A lot of sound compositions have to do with the sound artists expressing themselves. Usually if the pitch is high and the tone in high the sound that they are expressing either happy or a surprised feeling. If the pitch and tone is low they are usually expressing a sad or scary feeling. Now you see how it has an effect on sound art? (http://en.wikipedia.org/wiki/Pitch_(music))
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