The frequency spectrum
A fundamental tone, when combined with various harmonics of different levels, is perceived as a sound. The level relationships between these sonic elements change over time (controlled by envelopes, as described in Amplifier envelope overview). The combination of a number of harmonics is referred to as the harmonic spectrum or, more commonly, the frequency spectrum.
The frequency spectrum shows all individual sonic elements in a sound. It is shown low to high and runs from left to right over time. The respective levels of all harmonics are reflected vertically, with taller spikes indicating higher levels.
The illustration shows the level and frequency relationships between the fundamental tone and the harmonics at a particular moment in time. These relationships constantly change over time, which results in continuous changes to the frequency spectrum and, therefore, changes to the sound.
Download this guide: PDF