Exploring Sound Design Tools: Paulstretch

Have you heard this?

That video was, years ago, my introduction to "Paul's Extreme Sound Stretch" or just Paulstretch for short, a tool created by Paul Nasca that allows you to stretch audio to ridiculously cosmic lengths

Some years ago it was fashionable to grab almost anything, from pop music to the simpsons audio snippets, stretch them 800% and upload them to youtube. When the dust settled we were left with an amazing free tool that has been extensively used by musicians and sound designers. Let's see what it can do.

I encourage you to download Paulstretch and follow along:

Windows - (Source)
Mac - (Source)

The stretch engine

The user interface may seem a bit cryptic at first glance but is actually fairly simple to use. Instead of going through every section one by one, I will show how different settings affect your sounds with actual examples. For a more exhaustive view, you can read the official documentation and this tutorial before diving in.

As you can see above, there are four main tabs on the main window: Parameters, Process, Binaural beats and Write to file. I'm just going to focus on the most useful and interesting settings from the first two tabs.

Under Parameters, you can find the most basic tools to stretch your sounds. The screenshot shows the default parameters when you open the software and import some audio. 8x is the default stretch value, that may explain why so many of those youtube videos where using a 800% stretch.

The stretch value lets you set how much you want to stretch your sound. You have three modes here. Stretch and Hyperstretch will make sounds longer. Be careful with Hyperstretch because you can create crazily long files with it. There is also a Shorten mode that does the opposite, makes sounds shorter. If you want to make a sound infinite,  you can freeze the sound in place to create an infinite soundscape with the "freeze" button that is just to the right of the play button.

Below the stretch slider, you can see the window size in samples. This parameter can have quite a profound impact in the final result. Paulstretch breaks up the audio file in multiple slices and this parameter changes the size of those slices, affecting the character of the resulting sound as will hear below.

Let's explore how all these settings will affect different audio samples. First, here is a recording of my voice on the left and the stretched version with default values on the right hand side:

Cool. As you can see on the file name above, 8X is the stretch value while 7.324K is the window size in samples. Notice that the end of the file that Paulstretch created cuts abruptly. This can be fixed using lower values of window size to create a smoother fade out. This is the classic Paulstretch sound: kind of dreamy, clean and with no noticeable artefacts. You will also notice that, although the original is mono, the stretched version feels more open and stereo.

Just for fun, let's see how the Pro Tools and Izotope RX 6 pitch algorithms deal with a 8x time stretch:

This kind of "artefacty" sound is interesting, useful and even beautiful in its own way. But in terms of cleanly stretching a sound without massively changing its timbre, Paulstretch is clearly the way to go.

Let's play now with the window size value and see how this affects the result. Intermediate values seem to be the cleanest, we are just extending the sound in the most neutral way possible. Lower values (under 3K aprox) will have poor frequency resolution, introducing all sorts of artefacts and a flangerish kind of character. A couple of examples of applying low values to the same vocal sample:

Using a different recording we get a whole new assortment of artefacts. Below, you can see the original recoding on the left, the processed version with the default, dreamy settings on the centre and lastly, on the right, a version with a low window value that seems to summon beelzebub himself. Awesome.

On the other hand, Higher values (over 15K aprox) are better at frequency resolution but the the time resolution suffers. This means that, since the chunks are going to be bigger, frequency response is more accurate and faithful to the original sound, but in terms of time, everything is smeared together into a uniform texture with timbres and chracters from different sections of the original sample blending together. So, it doesn't really make sense to use high values with short, homogeneous sounds. Longer and more heterogeneous sounds will yield more interesting results as in this case different frequencies will be mixed together.

You can hear below an example with speech. Again, original on the left, dreamy default values on the centre and high values on the right. You can still understand syllables and words with a lower window value (centre sample) but with a 66K value the slices in this case are 2 seconds long, so different vocal sounds blend together in an unintelligible texture.

Basically, high window values are great for creating smearing textures from heterogeneous audio. Here is another example to help you visualize what the window size does.

On the left, you have a little piece of music with two very different sections: a music box and a drum and bass loop. Each of them is around 3-4 seconds long. If we use a moderate window size (centre sample below) we will hear a music box texture and then a drum texture. The different music notes are blended together but we can still have a sense of the overall harmony. On the third sample (right) we use a window size that yields a slice bigger than 4 seconds, resulting in a blended texture of both the music box and the drums.

Not only can you choose the window size, but also the type of window. Sort of the shape of the slices. Rectangular/Hamming deal better with frequency but they introduce more noise and distortion. Blackman types produce much less noise but they go nuts with the frequency response. See some examples below:

Adding flavour

Jumping now to the Process tab, here we have several very powerful settings to do sound design with.

Harmonics will remove all frequencies form the sample except for a fundamental frequency and a number of harmonics that you can set. You can also change the bandwidth of these harmonics. A lower number of harmonics and a lower bandwidth will yield more tonal results since a fundamental frequency will dominate the sound, while higher values will be closer to the original source having more frequency and nosie content.

See samples below, the first two are the original recording on the left and the stretched version with no harmonic processing on the right. I left the window size kind of low so we have some interesting frequency warping there.  Further below, you can hear several versions with harmonic processing applied and increasingly higher bandwidths. Hear how the first one is almost completely tone and then more and more harmonic and noise content creeps in. I's surprising how different they are from each other.

Definitely very interesting for creating drones and soundscapes, Paulstretch behaves here almost like a synthetizer, it seems like it creates frequencies that were not there before. For example:

Also worth mentioning are the pitch controls. Pitch shift will just tune the pitch as any other pitch shift plugin. Frequency shift creates a dissonant effect by shifting all frequencies by a certain amount. Very cool for scary and horror SFX.

The octave mixer creates copies of your sound and shifts them to certain octaves that you can blend in. Great for calming vibes. See examples below:

 

Lastly, the spread value is supposed to increase the bandwidth of each harmonic which results in a progressive blend of white noise in the signal as you push the setting further. The cool thing about this, is that the white noise will follow the envelope of your sound. This could be used to create ghostly/alien speech. Here are some examples with no spread on the left and spread applied on the right:

And that's it form me! I hope you now have a good idea of what Paulstretch can do. I see a lot of potential to create drones, ghostly horror soundscapes, sci-fi sounds and cool effects for the human voice. Oh, and also just stretching things up to 31 billion years is nice too.

Mini Library

Here is a mini library I've put together with some of the example sounds, some extended versions an a bunch of new ones. It includes creatures, drones, voices and alien winds. Feel free to use them on your projects.

Pro Tools Functions, Tips and Tricks for Sound Design

Here is a compilation of tips and tricks for sound design and editing with Pro Tools. Some of these shortcuts could be obvious to the seasoned Sound Designer but you’d never know, you might learn a new trick or two. For the purposes of this post, I’ll assume that most readers are Mac users, although most of this content should also be PC-compatible.

The post contains short videos which demonstrate the shortcuts discussed in each section. If you have Pro Tools at hand, I would recommend that you open it and follow along. Let's go!

Use memory locations to mark sync points and scene changes.
Pretty basic but worth mentioning. You can add memory locations to your timeline and use them to mark certain key moments. As you import new clips to your session, these markers will be very helpful in lining up different layers. You can also jump between markers with shortcuts, which is particularly useful in long sessions with multiple scene changes.

Shortcut Function
Enter (numeric keyboard) Create new marker at playhead position.
Cmd + 5 (numeric keyboard) Open the memory location window.
Opt + Click on marker Deletes the marker.
"." (numeric keyboard) + marker number + "." (numeric keyboard) Jump to a marker location

Note: If your numeric keypad is on Classic Mode you can skip the first "." when recalling a memory location.


Using X-Form + Elastic Properties
This is my preferred method for quick clip pitch and length changes. It doesn't work very well for big changes but is good enough for small adjustments and you can tweak both parameters independently This is not a real time process, the changes are rendered offline and you'll keep the original version if you need to go back to it.

To use this method, you will need to activate X-Form in the track elastic properties, it's just under the track automation mode. (Video Bellow)

X-Form pitch changes work great when you have a sound that is similar to what you need but you feel it needs to be a little bigger or smaller in weight. The results are not always natural sounding, but adjusting the pitch can sometimes bring a clip close to the sound you're looking for.

Also, being able to change the length of a clip makes your library instantly bigger. Now your clips may work on more situations as you can make them shorter or longer to fit in context.

And don't forget this tool could be also used as a creative resource. Listen to the following clip where some plastic bag impacts are extremely slowed down, creating a weird, distorted kind of Sci-Fi sound. You can hear bellow the original sound first and then the processed one.

Shortcut Function
Alt + 5 (numeric keyboard) Opens the elastic properties for the selected clip.

Tab to transients. 

Again, pretty basic but super useful. When activated, (under the trim tool or with the fancy shortcut) you can use the tab key to jump between transients instead of clip boundaries. Very handy when editing steps, gun shots or impacts.

This function is great when working with just a few short clips, but If you just want to create clip separations on transients on a long file with loads of steps, the best to do this would be to use the function "Separate Clip on Transients".

Shortcut Function
Opt + Cmd + TAB Toggles "Tab to Transients" on and off.
TAB Jump between transients or clip boundaries.
B Separate Clip.
No official shortcut, but keep reading for a workaround! Separate Clip on Transients

Shortcuts in the ASDFG keys (cuts and fades). 

Naturally, my left hand is usually in a WASD position but when editing in Pro Tools, your fingers should be on the ASDFG keys to allow you to quickly trim and fade clips. It might take some time to get used to using these, but in no time at all, it will become second nature. Remember that you need to be on keyboard focus to use these.

Shortcut Function
A Trim Start
S Trim End
D Fade In
F Cross Fade
G Fade Out

Ctrl + click to move a clip to the playhead position.

To align two clips, select the clip to which you want to align the other(s) and then press Ctrl + click on the second clip to align them.. Also works on markers. Simple and neat.


Move a clip from one track to another without changing its sync.

Just press and hold Ctrl while moving a clip from one track to another and it will keep its timeline position no matter how much you horizontally move your mouse.. Add Opt to the shortcut to also duplicate the clip.


Fill gaps. 

This is very useful when you have an unwanted noise on an ambience track.

To eliminate the offending noise, first select it and press Cmd + B to remove it. Then select and copy another similar region in the audio clip, ideally longer than the gap you have removed. Lastly, select the area to fill and do a paste special repeat to fill selection. You can then cross fade the boundaries to make it seamless.

You can use this method rather than copying a section of audio and having to adjust the clip manually to fill the gap.. this shortcut does that tedious work for you!

Last thing, if your selection when copying is smaller than the gap itself, Pro Tools is going to paste the same clip several times until the gap is filled. It will also create crossfades between these copies of your selection. This won't probably sound very smooth but it may work if the gap is not very big and/or the scene is busy.

Shortcut Function
Cmd + B Clear or remove selection from clip.
Opt + Cmd + V Paste special repeat to fill selection.

Easy access to your most used plugins 

You can select your preferred EQ and Compressor plug-ins by going to Setup > Preferences > Mixing.

You can also select you most commonly-used plug-ins to appear at the top of your inserts list, by holding Cmd and then selecting the relevant plug-in in an insert slot. This also works with AudioSuite plug-ins.


Have Audiosuite plugins at hand with window configurations.

The previous trick will allow you to have your AudioSuite plug- ins at hand but there is an even quicker and better way to quickly access AudioSuite plugins.

First, open the AudioSuite plugin of your choice, you can even do this with more than one plugin at the same time. Now, create a new window configuration using the Window Configurations window or the shortcut. You can then call that window configuration to summon the plugin or even incorporate it in a memory location as you can see in the picture on the right.

Keep in mind that window configurations can do much more than that, you can save any edit and/or mix window distribution set up and easily toggle between them.

More info.

Shortcut Function
Opt + Cmd + J Open Window Configurations.
"," + Number from 1 to 99 + "+" (Numeric Keyboard) Create new window configuration.
"," + Window Configuration Number + "*" (Numeric Keyboard) Recall window configuration.

Or impress your friends with custom shortcuts...

Memory locations + Window configurations are very powerful. But there is hidden feature that may be even better for accessing Pro Tools functions. You can create your own custom shortcuts for unmapped commands and without any external macro software.

As far as I know, this only works on mac. Just go to Apple > System Preferences > Keyboard > Application Shortcuts and add Pro Tools to the list if it wasn't there already. Now you can create (Plus symbol button) a new shortcut to any Pro Tools function your heart desires as long as that function appears on any Pro Tools menu. Even AudioSuite plugin names. You just need to type the exact name and then add the shortcut you want to assign to that given function.

This blew my mind when I discovered it, you can now access loads of functions even if they are buried under 3 sub-menus.
Here is a list of some of the custom shortcuts I'm currently using, I tend to use Control as the modifier key since Pro Tools doesn't use it much:

Shortcut Exact function name Description
Ctrl + C Color Palette Pimp those tracks!
Ctrl + S Izotope RX 6 Connect Opens the window to send audio to RX
Ctrl + R Reverse AudioSuite Reverse Plugin
Ctrl + V Vari-Fi AudioSuite Vari-Fi Plugin
Ctrl + T At Transients Separates a clip on its transients
Ctrl + E EQ3 7-Band AudioSuite EQ Plugin
Ctrl + G Render Renders Clip Gain
Ctrl + P Preferences...
Ctrl + D Delete Deletes empty tracks
Ctrl + Opt + D Delete... Deletes non-empty tracks
Opt + Cmd + S Save Copy In....
Ctrl + Opt + Cmd + B QuickTime... Bounce to Quicktime

As you can see, you need two distinct shortcuts to delete tracks since the dialog is different depending on the contents of the track. With the set up I have, using "Ctrl + Opt + D" will always delete the track, regardless of its content, but it will only show the warning window if the track has content on it.

Of course, these are only the ones I currently have, I change them all the time. There are many other functions that you could hook up like I/O, Playback Engine, Hardware, Make Inactive (for tracks). Go nuts!


Automation Follows Edit is your friend.

By default, is a good a idea to keep this option on, so when you move a clip, its automation moves with it. But sometimes, especially when doing sound design, you want to swap a clip with another without moving the automation so you can hear how the same processing affects a different clip.

Just remember to turn this back on when you finish or you may mess things up badly. In newer Pro Tools versions like 12 the button will go bright orange to remind you the function is off which is very handy.


Moving through the session

My workflow is based on the mouse wheel because that's what I had when I started with Pro Tools. It might not be the fastest or most efficient way of working but it’s what I’m used to and I can move pretty fast through a session with this method. 

I use the mouse wheel to move horizontally and I like to use the "Mouse Wheel Scrolling Snaps to Track" feature (Pro Tools preferences > Operation > Misc) so every mouse wheel click is a track's length.

To move horizontally, I use Shift + the mouse wheel. To zoom, I use Alt + the mouse wheel or the R/T keys.

Shortcut Description
Shift + Mousewheel Move Horizontally in the timeline.
Alt + Mousewheel Zoom in and out.
R Zoom out.
T Zoom in.

Automation

You don't usually need to do complex automations while designing but here are some handy shortcuts to speed you up so you can focus on the actual sound design. One of the most tricky and annoying things is to move automation around and to automate one or more parameters on a plugin. These shortcuts may help. For accessibility, I'll avoid talking about HD features.

Shortcut Function Comment
"," "." Nudge automation. Select a section of an automation curve and nudge it to position.
Really useful when you are early or late on a automation pass.
(Pictured in the video bellow).
Ctrl + Opt + Cmd + Click Enable automation. Use it on a plugin parameter to make it "automable" or on the "Plugin
Automation Enable" button to enable everything.
Ctrl + Cmd + Click Show automation lane. Shows the automation lane for the selected parameter. Saves me hours.
Ctrl + Cmd + Left & Right Arrow Keys Change Track View Flip through track views. Very handy to go betweeen waveform,
volume and pan views.

Import Session Data

This is a very powerful and somewhat overlooked feature that allows you to import audio and other information from any sessions.

The key concept is that you can bring different elements independently. You could, for example, bring one track's plugins or its I/O without bringing any audio. 

If you decide to import audio, you can choose between just referencing the audio from the other session or to copying it on your current session's audio folder which would be a safer option.

You can also bring memory locations and window configurations. Remember those fancy window configuration shenanigans I was talking about above? You could import your little creations from other sessions with this!


Show number of tracks

Just go to View > Track Number. Very simple, but sometimes you want to know how many tracks you have used so you can brag about your unreasonable layering needs.


Miscellaneous useful shortcuts

And finally, here are some random shortcuts and functions:

Shortcut Function Comment
"*" (Numeric Keyboard) Enter timecode. Lets you type in the counter window so you can jump to any point on the timecode.
Also, this counter acts as a calculator so you can type + or - to jump a certain
amount of timecode forward or backwards.
Shift + Cmd + K Export Clips as Files A somewhat hidden feature (it's on the clip list window, not the main menus
that allows you to quickly export any clip as a separate file. You'll be able to
choose the settings of the new audio file but remember this is not the same
as a bounce, inserts and sends won't be considered.
Alt + Cmd + "[" or "]" Waveform Zoom Changes the waveform zoom in or out. Very useful when you need to work
with a zoom level that makes sense with the material you have. 
Ctrl + Opt + Cmd + [ Reset Waveform Zoom Resets the waverform zoom in case you want to see how loud a clip really looks.
Ctrl + Shift +
Arrow up/down or mousewheel
Nudge Clip Gain. It even works with several of them at the same time. A must if you use clip
gain a lot. Keep in mind that you are going to jump in a determined amount of
dB that you can change at Preferences > Editing > Clips > Clip Gain Nudge
Value. I usually use 0.5 dB but sometimes I like a smaller value.
None, Double Click on a
Crosfade and select
Equal Power.
Equal Power
(Crossfades)
Use this when there is a drop in volume on a crossfade. This setting will make
the transition much smoother.

That's it. Questions? Suggestions? Did I forget your favourite trick? Leave a comment!