I am not expert in music.
There are number of [musical instruments](http://en.wikipedia.org/wiki/List_of_musical_instruments). One (especially a person who knows about music) can blindly recognize which instrument is being played just by listening to it. 

**I need mathematical explanation about following**

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> Every instrument (say Guitar, Harmonium , Violin like that) seems to be unique while listening. My basic question is why is it so?
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> Why different musical notes sound different on different instruments? 
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