In our continuing series featuring tips in audio post production in Pro Tools from Marcelo Cyro from the Oscar nominated animation - The Boy And The World.  In this article Marcelo demonstrates the use of the Doppler plug-in from GRM Tools in film sound in Chatô, o rei do Brazil, which was awarded Best Sound from ABC cinematography for 2016. Over to you Marcelo...

The doppler effect is the change in frequency of a wave for an observer moving relative to it’s source. The Doppler plugin from GRM Tools lets you move sounds through an audio space with changes in pitch that correspond to their movement. You can also transform sounds through loudspeaker modulation, create unusual vibrato effects

How Does Doppler Work?

Doppler simulates the effect obtained by moving sound through a two-dimensional space. A sound moving closer to the listener will be transposed upwards, while a sound moving away from the hearer will be transposed downwards.

Movements follow the position of the two-dimensional cursor, which you can add automatic circular movement. Based on a physical propagation model, this processing also provides the opportunity to explore non-realistic results by the decoupling of variations in amplitude and in the Doppler effect.

How I Used Doppler In This Example

To create a propeller effect we used some weird wind as source and with the GMR Tools Doppler plugin we were able to create the "rotational" oscillation effect of the propeller.

The first source that I use is a low end distorted wind and I do suggest to try to listen to this on good speakers or headphones. The second source is wind storm that I used to make the propeller of the airplane. 

It is great to use because you can control the speed of the rotation, and synchronize it with the movie, as you can see in the video example above and how easy and effective it is to use on a lot of other effects.