To Remove Frequencies Using The High-Low Pass Effect (Pro Only); Modulator Effect (Pro Only) - Adobe AFTER EFFECTS 7.0 Manual

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Change the focus from one sound to another over time. For example, in audio that contains both music and voice,
you can fade out the music while gradually bringing in the voice.
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Protect equipment from potentially damaging frequencies.
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Direct certain frequencies to specific equipment. For example, using Low Pass can isolate sounds intended for a
subwoofer.
Adjust the following controls for the High-Low Pass effect:
Specifies whether to apply High Pass or Low Pass.
Filter Options
For High Pass, specifies the frequency below which the footage is not audible. For Low Pass,
Cutoff Frequency
specifies the frequency above which the footage is not audible.
Specify the mix of unprocessed (dry) audio to processed (wet) audio in the final output. Common
Dry Out, Wet Out
values for removing frequencies are 0% for Dry Out and 100% for Wet Out.

To remove frequencies using the High-Low Pass effect (Pro only)

Determine if the unwanted sound has predominantly high- or low-frequency content.
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For Filter Options, choose High Pass if the unwanted sound has low-frequency content; otherwise, choose Low
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Pass.
Adjust the cutoff frequency to isolate the unwanted sound from the frequencies you want to keep. To help isolate
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the unwanted sound, apply the Audio Spectrum effect to a motion footage layer to see the magnitude of the
frequencies in the range you define. (See "Audio Spectrum effect" on page 442.)
Choose 0% for Dry Out and 100% for Wet Out.
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5 To verify that the frequencies you are cutting off are the ones you want to remove, switch to the opposite filter and
then preview the audio.
To identify which cutoff frequencies work best, do one of the following:
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Continue to adjust the cutoff frequency and preview the audio until you reduce or remove the unwanted sound
while minimally affecting the frequencies you want to keep.
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Set keyframes for different cutoff frequencies, and then preview the audio.
See also
"Previewing audio" on page 136
"Using keyframes" on page 192

Modulator effect (Pro only)

The Modulator effect adds both vibrato and tremolo to audio by modulating (varying) the frequency and amplitude.
Using Modulator, you can create a Doppler effect, such as when the perceived sound of a train whistle is higher in
pitch as it approaches an observer, and lower in pitch as it passes.
Adjust the following controls for the Modulator effect:
Specifies the type of waveform to use. Sine waves produce the purest sounds. Triangle waves
Modulation Type
produce more distorted sounds.
Specifies the rate in Hz at which the frequency modulates.
Modulation Rate
Specifies the amount of frequency modulation.
Modulation Depth
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