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April 30, 2013 / Randy Coppinger

Voice Processing – Extreme EQ

Typical EQ discussions look at frequency cuts and boosts intended to bring out desired qualities in the voice. But sometimes there are obnoxious problems that need to be fixed. Or we want to use EQ as an effect. Sounds like a job for extreme EQ manipulation.

When a performer works too close to the mic, and/or blows a lot of air, plosives may seem more like small nuclear blasts. All of that extra bass sounds unnatural and can be distracting. A severe low rolloff (high pass) filter can often make it sound normal again, but can also make everything else sound thin and terrible. A better solution: EQ only a small portion of the recording, the part where the plosive sounds bass heavy.

In a DAW, low frequencies appear longer than high ones. Compare what you hear with what you see to help locate just the part of the recording with the explosive sounding plosive. Separate the “pop” from the rest of the voice recording. Select just that part, apply a low roll off at 150 Hz and listen to it. If that kills enough bass to sound natural again, great. But often you will need to undo, set the roll off higher and listen again. Sometimes you can stop at 200 Hz, sometimes 250 Hz, other times you need to go even higher. Steep slopes like 12 and 18dB per octave seem to work well.

Any signal processing has the opportunity to create latency. Filters often change the timing of a recording. This means that once you get the frequency and slope worked out, the processed section of voice may no longer transition smoothly to the surrounding audio. One solution is to process a larger section of audio, cut it back down to a section that fits and slide it into place. A simpler and often quicker solution is to cross fade in and out of the processed section. Experiment with these techniques in conjunction with EQing the overly plosive section of audio and your p-pop elimination kung fu will get better and better the more you try.

Here’s a sweet tutorial for removing plosives in Reaper.

When a voice is well recorded, sibilance will have already been avoided through mic selection and placement. If all “s” sounds are harsh, simple EQ may not be a good solution. But sometimes a voice sounds sibilance free most of the time, with occasional harshness. Like occasional plosives, sibilance may be made to sound more natural by selecting only the small portion that sounds bad and EQing that only.

Sweep through the 3-12k Hz region with a narrow Q and a significant boost and listen for sibilance (see Boosts for details). Or have a quick look at an RTA for an obvious peak when you hear sibilance. If you can identify a frequency to cut, doing so may return that “s” sound to something more normal (less distracting). As with plosives, aim your EQ at the part of the recording that is sibilant and leave the rest unaltered. I find a Q of 4 or narrower is needed. The cuts are pretty drastic. Start with 6dB and listen. But there are times when 9dB, 12dB, 15dB or more may be needed to to get things sounding good again.

But if every “s” sound rips out your ears, EQing each one by hand could be a huge time suck. When a recording is consistently sibilant throughout, you may need a de-esser.

Recording on the other side of glass takes some effort. Recording underwater requires even more effort. Both of these can be approximated using extreme EQ. Set a high roll off (low pass) filter at around 8k Hz. Then adjust it lower and try different filter steepnesses until it sounds convincing. Rolling off for glass will be fairly subtle. Under water will be a lot more muffled.

My favorite way to make a voice sound like it is coming from a phone, intercom, toy speaker, megaphone, etc. is to play the voice through the device and re-record it. Nothing is quite as convincing as the real thing. But in a pinch, many of these sounds can be approximated with extreme EQ.

Take a low roll off (high pass) filter and set it higher than you would want for a full sounding, realistic voice. You want to set it higher than 100 Hz. Somewhere just below 200 Hz things start to get weird. And they get weirder the higher you go. Decide for yourself how thin you need to make the voice sound for the effect to be convincing. For a phone you might add some distortion and/or severely lower the bit rate to really sell the idea. For an intercom, try adding a short delay or tight reverb. For a toy speaker go especially high with the roll off and more severe with distortion than for a phone. For a megaphone, make greater use of delay… either louder than you might for an intercom and/or use a longer delay time.

Combine high roll off or switch to band pass filter for more vintage phone, intercom, toy, and megaphone effects. You’ll hear very narrow effects like this on some vocals during an intro, bridge, or other low fidelity moments in some songs. If you’re not trying to emulate something in the real world, experiment with really wacky settings and hear what works for your production. You can even automate frequency sweeps using band pass, high pass, or low pass filters to create a sense of motion, revelation, or closure.

Also in this Voice Processing series:
Frequency Cuts
Compression Effects
Compression Technique
Frequency Boosts

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