Studio Acoustics 6 min read Updated: October 2026

The Critical Distance (Dc) in Enclosed Rooms: Direct vs Reverberant Sound Field

In any enclosed acoustic space, sound energy consists of two components: the direct sound traveling straight from the source, and the reverberant sound field formed by millions of overlapping reflections bouncing off room boundaries.

Defining Critical Distance

The Critical Distance ($D_c$) is the exact physical distance from a sound source where the sound pressure level of the direct sound equals the sound pressure level of the reverberant sound field ($L_{\text{direct}} = L_{\text{reverb}}$).

$$D_c = \frac{1}{4} \sqrt{\frac{\gamma \cdot A}{\pi}}$$

Critical Distance formula where $\gamma$ is source directivity factor and $A$ is total room absorption (Sabins)

When mixing on studio monitors, the mixing engineer should always sit well inside the critical distance ($d < D_c$) so that direct sound dominates room reverberation by at least 10 dB.

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