Spectrum: Viewing in the Frequency Domain

When viewing in the frequency domain, a “spike” at a frequency indicates there is a sinusoid in the signal at that frequency.

**Figure 3:** Adding sinusoids at 5, 10, 15 Hz in both time and frequency domain.
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The height of the spike indicates the amplitude--all sinusoids here have a peak amplitude of 1.

The harmonic relationship between the partials can be seen by the even spacing between the “spikes”.

``Music 175: Spectrum'' by Tamara Smyth, Department of Music, University of California, San Diego (UCSD).