# How does one call the y axis of a waveform?

In many audio applications one can find a waveform representation, but the y-axis normally is never labelled.

Now, if you would plot your own waveform and wanted to label it, what would be a correct label for the y-axis?

For me the y-axis represents vibrations, but for "vibration" or "relative vibration" as label sounds strange, I am also not 100% sure, if vibration is the correct term. Thank you for any hint!

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X is time

Y is amplitude, volume, voltage, dB or pressure, depending on exactly where you are measuring, but they can be considered equivalent in an audio scenario.

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What you've marked in the image is the scale. This will labeled with the unit of measurement. This is typically decibel (dB), percent (%) or volt (V).

The y axis represents the amplitude.

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the problem with the term "amplitude" is, that amplitude is only the maximum of a vibration. scale is probably not wrong, but isn't it a little bit too trivial? ;-) Still open for new terms :-) And thanks, doc ;-) – stefan.at.wpf Jun 24 '12 at 14:24
A dB scale always looks different from what's asked about here, because it's logarithmic. — @stefan.at.wpf: amplitude is not necessarily just the maximum of a vibration, it can also mean the... well, amplitude at any single point in a waveform. – leftaroundabout Jun 24 '12 at 17:46
@stefan.at.wpf You didn't get it. - You have to understand, the waveform represents a lot of values. These values were measurements within a time frame. Every single value is the amplitude for a specific moment. So the waveform represents a continuous series of amplitude measurements. - Second: You joker. I didn't wrote you should label it "scale". I wrote it will be labeled with the unit of measurement. – DoktorHauser Jun 25 '12 at 9:20
Thank you Doktor, I somehow managed to read this simple answer wrong ): Sorry. leftaroundabout and Doktor, thank you for the "amplitude at any single point in a waveform", that's a neat logical "trick". So I am now happy with the term amplitude :-) – stefan.at.wpf Jun 25 '12 at 9:29
Vibration is frequency, so if you want to see a snapshot of the vibrations then you should switch to spectral or FFT view. – ObscureRobot Jun 25 '12 at 14:38