A meta-analysis found that white and pink noise provided a small but statistically significant benefit on laboratory task performance for children and young adults with attention-deficit/hyperactivity disorder (ADHD) or elevated ADHD symptoms. The study analyzed 13 studies involving 335 participants.

Researchers from Oregon Health & Science University and Purdue University published a study in the Journal of the American Academy of Child & Adolescent Psychiatry. They found an overall effect size of g = 0.249 (95% confidence interval [CI] = 0.135-0.363; P < .001) for improved task performance with white or pink noise exposure in individuals with ADHD or high ADHD symptoms. The same noise conditions had a negative effect (g = -0.212; 95% CI = –0.355 to –0.069; P = .004) on task performance in non-ADHD comparison groups.

Methods and Results

The researchers conducted a systematic review following PRISMA guidelines, searching databases including PubMed/MEDLINE, PsychInfo, and Scopus. Initial screening identified 753 records, with 601 unique studies remaining after removing duplicates. Twenty-three full-text articles were assessed for inclusion, resulting in 13 studies for meta-analysis.

Eligible studies included study participants with diagnosed ADHD or elevated ADHD symptoms, used laboratory measures of attention or executive function, and compared white or pink noise interventions to low/no noise conditions. Eleven studies included pediatric participants, while two focused on adult college students. Nine studies included participants with formal ADHD diagnoses, and four included participants with elevated ADHD symptoms. Eight studies included participants who withheld ADHD medication on testing day, while three studies included some or all participants taking medication during testing.

The included studies, published between 2007 and 2022, were conducted in various countries including Australia, Belgium, Canada, Taiwan, the United Kingdom, the United States, Norway, and Sweden.

Studies used various tasks including go/no-go tests, Spanboard tests, Conners Kiddie Continuous Performance Test, and verbal memory assessments. 

Key findings of the review included:

• Minimal heterogeneity across studies (I^2 < 0.01, P = .93)
• No significant moderator effects for age, diagnostic status, or task type
• Individual study effect sizes ranged from g = 0.013 to g = 0.546
• Peer-reviewed studies (n = 10) showed g = 0.243, non–peer-reviewed studies (n = 3) showed g = 0.249
• No evidence of publication bias using funnel plots and trim-and-fill methods
• GRADE assessment indicated moderate certainty of evidence.

Sensitivity analyses demonstrated result robustness:

• Varying cross-condition correlation from 0.00 to 0.90 did not significantly affect results
• Excluding studies with a specific author (G. Söderlund) as first or senior author did not significantly change results (remaining n = 7, g = 0.228; 95% CI = 0.097-0.359).

For participants without ADHD, 11 studies (n = 335) showed a negative effect of white/pink noise (g = -0.206; SE = 0.063; 95% CI = –0.330 to –0.081; P = .001).

Limitations and Future Directions

The authors noted several important limitations of the study, including the lack of adequate control conditions and difficulty with masking in many studies; limited data on optimal noise levels for sustained use and potential hearing risks; insufficient data on variation in effects by sex, race, or ethnicity; and a small number of studies precluding powerful tests of symptom severity effects.

While not statistically significant due to small sample size, studies with unmedicated participants showed qualitatively larger effects compared to studies with medicated participants.

Theoretical Implications

The authors noted that the findings align with hypoarousal or optimal arousal theories of ADHD, which suggest that individuals with ADHD may respond differently to environmental stimulation. The authors discussed potential mechanisms, including the activation of stochastic resonance, whereby random noise can amplify neural signals in complex systems.

The authors declared having no competing interests.