Brown noise (also called red noise) has a power spectral density of 1/f^2, dropping 6 dB per octave. It sounds deep and rumbling. No peer-reviewed study has specifically tested brown noise with ADHD participants. The Nigg et al. (2024) meta-analysis explicitly states: "effects of other types of colored noise, including brown noise, in ADHD have not yet been empirically assessed."
The strongest indirect evidence comes from Lu et al. (2020), who tested red noise (mathematically identical to brown noise) in a general-population sample. All three noise colors tested (red, pink, and white) improved psychomotor speed, executive function, and working memory compared to quiet conditions. Red and pink noise were rated the most comfortable listening conditions. Notably, pink noise was the only color that significantly improved sustained attention on its own, but red noise performed well across the broadest range of cognitive measures.
Brown noise is included in Ebbi based on this indirect evidence, the theoretical plausibility that the stochastic resonance mechanism applies across noise colors, and strong demand from the ADHD community on social media.
