Timbre is a little more difficult to understand than some of the other elements. Put simply, it is a word which explains why a violin sounds like a violin and a drum sounds like a drum. Timbre is the reason you can recognise your mum's voice over the phone even if she has a terrible cold. Scientifically, when you or an instrument produce sound, you not only produce one frequency, but also produce a particular combination of 'overtones'. This is the 'timbre' or 'tone quality' or 'colour' of the sound - the instrument's special sound signature.
A trumpet can sound like a completely different instrument with a mute stuffed in the end! A classical guitar and an electric guitar sound worlds apart. Violins can pluck and bow.
Click on the horns on the right to hear some very unique sounds