Boom Mic Distance Calculator

About this calculator

Sound pressure level follows the inverse-square law — every time you double the distance from a sound source, the level drops by about 6 dB — which makes microphone placement on a boom pole a precise, calculable decision rather than guesswork. This calculator finds the dB change when a boom mic moves from one distance to another using ΔdB = 20·log₁₀(d₁/d₂).

Moving a mic from 2 feet to 4 feet away from a speaker's mouth drops the level by about 6 dB — enough to noticeably hurt the signal-to-noise ratio in a room with background hum or hiss. That's why boom operators aim to hold the mic as close as the shot allows, typically 1–3 feet from the actor's mouth while staying out of frame.

Boom operators and production sound mixers use this relationship to judge how much headroom they're trading away every time a wide shot forces the mic further from the actor than the ideal working distance.