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3.2.2.2
Spectrum, and Frequency-Domain Attributes
Instead of looking at a signal as something in motion through a period of time, we can look at the collection of
sine-wave components of the signal. In such graphs, the horizontal axis is a frequency range (instead of a time
period), and we indicate each spectrum component with a single vertical line in the graph. The height of the line
indicates the strength of the component at that frequency. This is the frequency-domain, or spectral-domain, view
of a signal.
It is the distribution and relative strength of spectral components that we experience as the tone-color of a sound
or sounds. “Bright,” “dull,” “sharp,” “tinny,” “heavy,” and so on—these are all descriptive words for the spectral
attributes of sounds.
3.2.2.2.1
Harmonic Series
The spectral view of any periodic signal has components at simple multiples of the signal frequency. For example,
suppose we examine a sawtooth wave at a frequency of 110Hz. It will have components at 110, 220, 330, 440,
and so on.
