Recreating the Doppler Effect in Bitwig Studio

Tutorial | Feb 02, 2023

In this video, I demonstrated how to recreate the famous Doppler effect within Bitwig Studio using an FX grid. I explained how the sound from a car driving past you would pitch up until it is directly in front of you and then pitch down as it moves away from you. To achieve this, I used a modulator, an absolute module, and an X and Y pad. I also used a logarithmic modulator and an convolution reverb to simulate a more realistic sound. Finally, I provided a preset with the settings used in the video in the description below.

You can watch the Video on Youtube

What is the doppler effekt in audio? #

The Doppler effect is an acoustic phenomenon in which the frequency of a sound wave changes as the source of the sound and the observer move relative to each other. As the source of the sound moves away from the observer, the frequency of the wave gets lower and the sound appears to be pitched down. As the source moves towards the observer, the frequency of the wave increases and the sound appears to be pitched up.

For what is the doppler effect used in audio? #

The Doppler effect is used in audio to create the impression of a sound source moving in relation to the listener. By manipulating the volume and pitch of the sound, the Doppler effect can make it sound like the sound source is getting closer, then moving away again. This effect is often used for creative purposes in music production, sound design, and video games.

How can we re-create the doppler effect in Bitwig? #

To recreate the Doppler effect in Bitwig, you will need to use the FX Grid and a few modules such as a modulator, a delay, and a panner. Use the modulator to control the volume and the delay to control the pitch. Use the panner to move the sound left and right, and use the X and Y output of the pad controller to control the sound. Use the modulator to attenuate the volume, and use the absolute module to turn negative values into positive values. Finally, use a convolution reverb to add a sense of distance to the sound.

Transcription #

If you don't want to watch the Video, or search for a specific topic, here is the transcription of the video with links to video markers:

[00:00.000] Hey folks, today it's about recreating the famous Doppler effect inside of Bitwig Studio.
[00:07.640] And to explain this roughly, this is not an physics experiment, right?
[00:12.160] So it's not about precision, it's more about explaining what happens in the real world.
[00:17.960] So this is you on the street, right?
[00:21.400] And there's some kind of car on the street driving past you or up to you.
[00:27.400] And you kind of hear the engine from the car.
[00:32.080] But because the car moves and it also moves up to you, the sound waves are getting squeezed
[00:39.920] together, which means it sounds like pitched up.
[00:43.760] So you hear the sound of the car engine, but it's pitched up until it's exactly in front
[00:50.160] of you.
[00:51.160] The car is also the loudest and the pitch is more or less static.
[00:57.120] But as soon as the car drives past you and away from you, you still hear the sound from
[01:04.360] the car engine.
[01:05.720] But now it's the opposite, the sound waves are getting stretched out and they sound kind
[01:12.120] of pitched down.
[01:14.560] And this is what we are trying to simulate inside the grid with some easy patching, some
[01:21.040] easy modules.
[01:22.040] I want to show you this.
[01:24.280] So this is here our sound source.
[01:26.240] So this is not what we are talking about.
[01:28.840] It's just a placeholder for some kind of sound effect.
[01:31.680] Maybe you have a car sound, an engine sound, or maybe some, I don't know, a spaceship or
[01:39.040] whatever that you want to have to fly by.
[01:43.000] So this is our sound engineer.
[01:51.280] So it's just, you know, just some kind of placeholder sound here.
[01:57.280] Maybe a peak limiter on there.
[02:00.080] Okay.
[02:01.080] So and now we want to implement this Doppler effect here with an FX grid.
[02:06.440] And we know we need to change the volume because sometimes the sound effect or the sound source
[02:15.600] is close to you.
[02:17.840] And sometimes it's far away.
[02:19.360] When it's far away, then you probably want to tune down the volume.
[02:24.320] And then we need a delay and the delay is for implementing the squeezing and the stretching
[02:31.640] of the sound waves, which means pitching up or pitching down the pitch.
[02:39.520] And also we need a pen to move the sound to the left or to the right.
[02:46.920] And as an interface, we are going to use the X and Y pad here.
[02:52.000] And I usually never use this, so I thought it's a great opportunity to actually use this
[02:57.040] here in the grid for this experiment.
[03:01.880] Okay.
[03:02.880] So we have two outputs here for X, Y and coordinates.
[03:06.640] And we also select this device here and switch it to bipolar mode on the left side.
[03:12.720] So now we have positive and negative ranges, right?
[03:15.400] Positive, negative, positive and negative.
[03:19.440] And this is here the Y out, up and down.
[03:23.880] Okay.
[03:25.380] So the first thing we want to implement is basically the volume change.
[03:28.880] So every time the sound source is not in the middle here of this X, Y pad, we want to tune
[03:37.200] down the volume.
[03:39.880] So we do this with the modulator, of course.
[03:45.080] And we use here the output of maybe the blue first, right?
[03:50.120] And then we modulate your attenuate.
[03:52.320] So every time we go up, you can see the volume goes down, right?
[03:57.760] But when you go in the negative range, nothing happens.
[04:00.280] Why?
[04:01.280] Because we only modulate it here in the negative range.
[04:05.360] And when we go negative here, it goes in the positive range.
[04:08.760] So we have to switch the negative values to positive values.
[04:13.080] We can do this with an absolute module here.
[04:17.240] And this one turns basically negative values to positive values.
[04:21.320] And positive values stay positive.
[04:23.360] So when you use an oscilloscope here, and use the output here, and see when we go up,
[04:30.400] we go positive, when you go negative, we go negative.
[04:35.480] When we use here the absolute with this, you can see positive goes positive, negative
[04:41.900] goes also positive.
[04:43.400] Okay.
[04:44.400] And this is exactly what we need.
[04:47.440] So you modulate your attenuate with this.
[04:51.040] So we go positive, and it goes quiet, go negative, and it also goes quiet.
[04:57.160] So it's exactly what we want.
[05:00.280] And we also probably want to use the modulator out and switch this to logarithmic, which
[05:07.320] means here it gets faster, quiet.
[05:12.840] And then at the end, it becomes more fine grained, right?
[05:19.160] You can see at the first few millimeters, first few inches, are doing a lot of modulation.
[05:31.360] And then at the end, you need to move more and more to actually modulate something, right?
[05:40.000] It's a different curve, a different modulation curve, that's what I want to say.
[05:44.080] And then we also need to do this here with these ones, with what's that, it's X out.
[05:52.760] So we do the same.
[05:56.560] And we just add this here, do that.
[06:02.160] So left, right side, we move away, left side, we also move away.
[06:06.560] So let's try this out.
[06:31.840] So basically you are always here in the center of this XY pad, and this is your sound source,
[06:36.680] and you can move the sound source around you, and then see what happens.
[06:41.240] So now we have here the volume change, let's call this volume, volume change.
[06:47.880] So now we implement here the pitch.
[06:51.040] So we basically do kind of the same thing without the absolute, I think.
[06:57.680] So let's use this here, and let's modulate delay, let's see what happens.
[07:15.880] So we also need here probably an absolute.
[07:44.360] So we need to implement this here also for left and right, so we do that the same.
[08:02.400] So we need to find here also nice modulation amounts, maybe that's a bit too much here,
[08:23.920] to simulate the real world.
[08:25.160] So this is not about precision, it's more about does it sound good or realistic or does
[08:30.640] it sound believable.
[08:33.880] So you can find here the sweet spot of all these modulations if you want to.
[08:39.800] So now we have this, we also want to use the pen for the left and the right, so we need
[08:48.480] the red out here, let's use this.
[08:54.360] So if we move to the right here, we want to modulate all the way to the right, okay let's
[09:25.280] So this is one way of doing it.
[09:30.000] We can also use here maybe a convolution reverb, and this is maybe I find some real places
[09:39.920] here, real rooms, and you probably are better off here with some main hall, let's see, it's
[09:52.280] maybe too big, wooden attic, okay let's use this.
[10:12.200] So now we can basically say when the sound source here is close, we can take here the
[10:18.840] volume out, when the sound source is close, we want to have pretty close sound, so less
[10:32.040] room, we want to have less room in there, and we want to have as much as possible try,
[10:39.040] a try signal, and then when we move away, we want to hear more the room instead of the
[10:52.480] close sound source.
[11:11.000] And you probably also can just use my penner, my binaural or realistic penner from yesterday's
[11:20.560] video in this instead of just using here the pen knob, so you can implement here after in
[11:26.480] the postfx, can just input here my penner from yesterday's video, and use that for more
[11:32.240] realistic panning, and that's it for today's video, so I put the preset here in the description
[11:37.800] below so you can download it if you want to, and thanks for watching, leave a like if you
[11:42.680] like the video, subscribe to the channel, thanks for watching, and I'll see you next
[11:46.200] time, bye.