Think of FFT like music notation - a separation into notes, dynamics, and tempo. Alexander Graham Bell came up with the idea of increasing the capacity of tele

Think of FFT like music notation - a separation into notes, dynamics, and tempo. Alexander Graham Bell came up with the idea of increasing the capacity of telegraph lines by combining several 'dit-da-dit' streams at different pitches. He called it a 'harmonic telegraph'. The idea was that a mechanical arrangement of reeds tuned to different pitches would pluck out each stream of data. This insight eventually led to the invention of the telephone. Finally, if 'orthogonal basis set' is difficult to understand, think of giving someone 'left/right' driving directions. An FFT would then (roughly) be the mathematical equivalent of 'driving directions' for a clip of music or speech.