Taming Vocal Plosives

Seven Tips From the Pros
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Seven techniques pros use to tame vocal plosives

PLOSIVES—THOSE nasty b and p consonants that explode out of the mouth with a burst of wind—can mar a vocal track by causing a mic to produce low-frequency thumps and pops. At best, these boomy artifacts distract the listener from a song’s vibe and eat up your mix’s headroom. At worst, they can damage your subwoofer with repeated occurrence.

In this article, I’ll detail methods used to break the wind. The best strategy is to prevent vocal pops in the first place.

Use a Nylon Pop Filter The foam wind screen that is supplied with most condenser microphones will tame plosives, but not without also severely dulling high frequencies. A nylon pop filter is a much better tool for the job, as it will subdue plosives while fully preserving detail, air, and nuance in the performance. For the greatest protection from pops, place the filter close to the singer’s mouth and several inches from her microphone.

Change the Mic’s Height If you don’t have a pop filter at your disposal, or it’s not getting the job done, raise or lower your mic on its stand a couple inches so that the singer’s mouth isn’t blasting directly at the mic’s diaphragm. Just be aware that raising the mic will result in a more nasal sound, while lowering it will emphasize the singer’s chest register. So if, for example, the singer sounds thin to begin with, lowering the mic will lend better balance to his or her tone than raising the mic would.

Avoid Using a Small-Diaphragm Condenser Large-diaphragm condensers and moving-coil dynamic mics are less sensitive to plosives than small-diaphragm condensers (SDCs). If you must use an SDC to record vocals (or want to for creative purposes), place the mic a considerable distance from the singer or point it at the ceiling and have the vocalist sing over the top of the head capsule. The takeaway is to avoid having the singer puffing on-axis and at close range to the tiny, lightweight mic diaphragm, or it will surely pop.

Select a Less Directional Polar Pattern Setting a multipattern condenser to omni mode will make it the least vulnerable to vocal plosives. As you progressively advance the polar pattern through cardioid, hypercardioid and bidirectional modes, the mic’s sensitivity to plosives will increase. As long as you don’t need the off-axis rejection and bass-proximity effect that the more directional patterns inherently lend, opening up the mic’s polar response (toward omni) is a good strategy for reducing vocal pops and thumps.

Up until this point, we’ve looked at ways to avoid recording vocal pops in the first place. If your track is already polluted with unruly plosives, there are a few ways you can subdue them in the mix.

Fig. 1A. The waveform for a vocal track clearly shows a plosive at the start.Fig. 1B. A tiny slice of audio is cut immediately before the plosive’s onset to create a new region. A fade is then created at the start of the region to attenuate the plosive. Fade In The most reliable and transparent way to suppress a vocal pop is to use your DAW’s fade tool to fade in the attack portion of the plosive (see Figures 1A and 1B). A linear fade will usually do the trick. Adjust the length of the fade so that the consonant is still audible and intelligible, but keep the fade long enough so that the thumping bottom end is quelled.

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Use a Filter Where a vocal track is infested with many pops, you may not have the time to fashion a fade for each instance and still meet your client’s deadline or budget. The solution is to slap a highpass filter (HPF) on the track.

Fig. 2. An HPF is fashioned in FabFilter Pro-Q to suppress vocal pops. The FabFilter Pro-Q equalizer plug-in does a great job for this application (see Figure 2). Adjust the filter’s slope so that it’s very steep: 48 dB/octave. Fine-tune the filter’s corner frequency to find the best compromise between attenuating the vocal pops and preserving the singer’s bottom end. Unless the track is for a bass or baritone singer with a signature bottom end you must fully preserve, you can usually begin rolling off bass frequencies below 100 Hz without making the vocal sound thin. Because the filter’s action will extend higher than the corner frequency, you’ll want to set the latter to roughly 70 Hz to produce the desired response.

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Fig. 3. The Waves C4 plug-in is used to dynamically diminish the effect of vocal pops without thinning the overall timbre of the track. Compress the Bottom End If an HPF thins the vocal track too much, try compressing the plosives using a multiband compressor. Be aware that most plug-ins won’t do the job without throwing the baby out with the bath water. The Waves C4 Multiband Parametric Processor is the rare exception and the most capable plug-in I’ve used for this purpose (see Figure 3).

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Switch C4 to Electro behavior and hardknee response. Set the bass band’s crossover to around 110 Hz, and bypass the other (higher) bands. Plunge the bass band’s range control to -24.0, and dial in super-fast attack and release times. Adjust the band’s threshold so that C4 attenuates plosives but doesn’t compress where they don’t occur. You may not be able to make the low-end thumps completely inaudible, but they’ll sound a lot less noticeable after C4 is through with them.

Michael Cooper is a recording, mix, mastering and post-production engineer, a contributing editor for Mix magazine and the owner of Michael Cooper Recording (www.myspace.com/michaelcooperrecording) in Sisters, Ore.