Proximity effect
The extra bass a directional mic adds when you speak very close, creating that warm radio voice or an unwanted boom.
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What it is
Directional microphones boost low frequencies as the source gets very close. That is the proximity effect: the warm, chesty radio sound you get by speaking a few inches from a cardioid mic. Figure-eight mics usually show it strongly too, while pressure-operated omnidirectional mics largely avoid it. The exact amount depends on the microphone: the Electro-Voice RE20 uses a Variable-D design to suppress it on purpose, which is why radio booths are full of them, while a Shure SM7B hands you a bass rolloff switch instead.
Use it deliberately when a thin voice needs weight, or avoid it by backing off and keeping the speaker at one marked distance. Mic position is the first tone control: moving from 2 inches to 8 inches can change the low end more naturally than a large EQ boost, while also capturing more of the room.
Gotcha: the flattering bass comes bundled with more plosives, mouth noise, and level swings every time the speaker moves. A pop filter blocks air blasts but does not remove the bass rise. Pick a distance, angle the mic slightly off-axis, and high-pass only after the position is consistent.
Ask AI for it
Record a warm voiceover on a Shure SM7B using proximity effect on purpose: place the mouth about 6 inches from the grille, keep that distance fixed, angle the mic 15 degrees off-axis, and use a pop filter for plosives. Record a second take at 2 inches and a third at 10 inches, level-match all three, choose the closest take that stays clear rather than boomy, and apply an 80 Hz high-pass filter only if rumble remains.