# 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! 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.

• 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

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.