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I'm pretty new to sound design and currently working on a soundscape project for school. I want to add that "shell shock" silence effect, like when a grenade goes off to close to a character, but I'm not having any luck. Anybody have any suggestions? I'm working in ProTools 9.
A common method is to use the Signal Generator AudioSuite and generate a sine tone @ 7-12Khz. You can then use the 1-band EQ set to a low-pass with a steep rolloff (24dB/oct) with a slight resonance and automate it down to a cutoff of around 120-200Hz. To augment the effect you could increase the Q on the filter when it reaches the lower frequency, even use a delay/phase effect. Tip: Using a short delay time with a mix of ~30% @ <20ms you can also achieve comb filtering effects.
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What you could do is process the sound multiple times with AudioSuite reverb and EQ it to make it sound somewhat dull. Maybe add some reverse sounds in there and a light flapping or fluttering and at the end of the sides of the stereo field use a particular sound perhaps a ringing or someone screaming but have it processed so that it doesn't sound like a scream at all maybe by pitching it up, time compressing it, and duplicating it a bunch with EQ.
You could go a little more figurative with it and pull everything, all of the sound, and replace it with something really uncomfortable, two slightly mismatched tones (100hz or something), maybe some low-passed thunder.
The filter thing is a little cliche for my liking, but then again, it's probably accurate...
I'd use a filter and a synth. Use the filter to create a low-pass and remove almost all of the sound, then sweep the frequency back up as the "shell-shock" effect wears off. While the sound is filtered out, use the synth to create a high pitched "whine". A sin wave will probably work for this.
This is just off the top of my head, it might not work, but it could be a good place to start. Let us know how you get on!
EDIT: Just saw you're using PT9, you'll be able to get the whine from the Vacuum instrument and you would be able to automate the EQ3 plugin for the filtering.