Show Spectrum

[ross_IOr]

Hello everyone, I have a questionabout the spectrum. Why if I do "shows the spectrum" I get an amplitude of the sound with negative values?

[steve]

Topic moved to the Audio Processing part of the forum.

If you are referring to "Plot Spectrum", the reference level is a 0 dBFS sine tone. If the amplitude of a frequency component is above the reference level its dB level is positive, if below the reference level its dB level will be negative. For "normal" signals, the levels will always be less than the reference level, so will be negative.

[ross_IOr]

How does the reference level is define?

[steve]

The reference level is a 0 dBFS sine tone.

Example: Generate a tone from the "Generate menu > Tone" and set the "Waveform" to "Sine" and the amplitude to 1. This will produce a sine tone that has an amplitude the full height of the track (0 dBFS). Select the track and observe that in Plot Spectrum the amplitude is 0 dB.

For more information about Plot Spectrum, see: http://manual.audacityteam.org/man/plot_spectrum.html