Golden Eyes: Experiments with Audio - Part 2 (are you shaved?)

Continuing from the Part 1, let's look at the waveform for track C:

Track C

If you are familiar with waveforms, you may recognize the apparent shaved-ness of the data here. I have to point out that all of the processes/artifacts has been applied to each instrument part separately and then they are glued together. Because of that, the flatness is at different amplitudes for each part as can be seen above. If we zoom into the orchestra part, it is obvious that the flat shaving is amplitude dependent and the quiet parts are not affected:

Orchestra part

Let's compare it with the original (select both audio clips in Cubase and then select 'events to part' from the Audio menu then press Enter):

Comparison of the orchestra part

Now the effect is clear! Remember to compare the left channels and right channels with each other. There are two main ways to do this effect to an audio: 1) clipping 2) limiting/maximizing. Of course clipping can also be considered as a crude type of limiting/maximizing. In clipping, the digital audio signal has become above the maximum representation capacity of the digital audio format and become cut-off abruptly. In limiting/maximizing, the audio has been similarly prevented to go above some limit but the transition to the cut-off is more gentle to prevent audio artifacts and degeneration. To make it clear, clipping is 'bad' and you don't want it to happen unless going for that specific effect. On the other hand limiting (which is a form of compression) and maximization are very common processes in the audio world but their specific usage is outside the scope of this post.

So, which has been applied here? We need to zoom in further:

Zoomed in to orchestra part

...and further:

I see waves itself!

..and further:

Shaving in plain sight

Now we see the individual waves and it looks like digital clipping more and more. If we zoom in further in the audio part editor in Cubase, the display changes to lines:

Really zoomed in

Here, the cut-off parts look flat with some exceptions. For a sound wave flatness is usually audible as pops and clicks if separated out in time, but if they are really frequent in a small time period (as in here, look at the timecode) then it sounds cracked and unpleasantly distorted (clipping distortion). (If you remember that sound is essentially a continuous or smooth change of air pressure as a function of time, the musical content will be essentially removed from these flat parts).

Even further...

I produced this effect by turning up the volume fader of the main output in Cubase allowing it to clip and then bouncing the result into the project. Let's overlay the differences showing the clipping line:

Overlay of the effect

It is interesting that the clipped parts are not actually completely flat as expected; but instead almost dips or bounces back as the clipped data goes higher. It is really weird and if anyone knows why this is happening please share it in the comments. I think this may be the result of how Cubase or my audio interface are handling the clipping data.

As another example, let's look at the drum kick clipping. Here the longer wavelength low frequency part of the kick drives the data over the clipping point. Since the higher frequencies 'live' on the lower frequency waveform, they are also gone forever (apart from that interesting dipping effect).

Overlay of the effect in the drum kick

This will provide a reference point when we compare the results with the more gentle maximizing and compression effects. In the next part I will look into phase inversion and difference of two tracks which will come really handy for our analysis.

Take care until then,
Cagil

Continue with Part 3