P..p..plosives

Plosives are an engineers nightmare. They crop up even when you’ve done everything in your power to prevent them.

For those who don’t know, plosives are the powerful pop sound you get when pronouncing certain letters (p, b, t, g, k, d). You can read the simple science behind them here.

The phenomenon is common with hypercardioid or cardioid polar pattern mics. Polar patterns show where the microphone picks up sound from.

Cardioid vs. Hypercardioid polar patterns

Inside of a cardioid microphone

The diaphragm of the mic is affected when the sudden pressure of the plosive and hits the backplate insulator. The diagram above shows how close the two are. It takes a little while for the diaphragm to regain its shape so, if a sentence has been recorded, the words after the plosive can be affected too. Sound on Sound have a really detailed article about them which you can read here.

Hakan P110 pop-shield

When recording a pop-shield is set-up to prevent plosives. The pop shield should be more than a pair of tights round a coat hanger (we’ve all been there) and positioned1-2 inches away from the diaphragm of the mic. It’s important to keep the mic from being in direct line of the vocalists mouth, whether it is slightly to the side or at forehead height. Sometimes the plosives still creep through which leaves it up to post production to correct the issue.

Plosives occur around 150Hz and lower, so a roll-off is usually what you need to get rid of them. If a simple EQ roll-off doesn’t work, there are a number of plug-ins that have been developed for this specific problem, FabFilter Pro-Q and Waves C4. Have a look at this article for more information on the plug-ins: Taming Vocal Plug-ins.