Analysing Sound

A signal Generator connected to a loudspeaker can produce a very pure note. It contains only one frequency of sound. An oscilloscope will produce a trace of this sound for us.

Most sounds, even ones from musical instruments, contain lots of different frequencies mixed together. We will learn more about harmonics in the next module.

Here is a display that you might see on a home stereo. What information is it telling us?

A frequency spectrum shows us      a) What frequencies are present and       b) their relative amplitudes

Trace	Frequency Spectrum
Pure Note 800Hz
Note from piano (middle C)
Low Voice
High Voice
White Noise (all frequencies present)