Noise Generator

What the research says

Two effects are studied in different literatures, and they do not favor the same noise.

Masking is subtractive: a steady noise covers an unwanted sound, usually speech, so the speech is harder to understand and less distracting. Office work uses pink noise, or a curve falling about 5 dB per octave, which sits between pink (3 dB per octave) and brown (6 dB per octave). White noise masks too, but it is hissier and less well liked. Brown noise has little energy in the speech band, so it is a weak speech masker.

Focus without a competing sound is additive: the comparison is silence, and the proposed mechanism is stochastic resonance. A moderate amount of external noise can help a neural system that is under-aroused. That benefit shows up mainly in people with ADHD or high inattention, and the trials are almost all white noise, with a little pink. For people without those traits, the same noise usually does nothing or slightly hurts performance. Controlled brown-noise trials of this effect are essentially missing.

Masking an external sound

• Selection of meaningless steady noise for masking of speech. Applied Acoustics, 2004. Among steady noises, band-limited pink noise masked speech at the lowest level.
• Study on achieving speech privacy using masking noise. Journal of Sound and Vibration, 2006. Follow-up: the same band-limited pink noise as a speech-privacy masker.
• Effects of five speech masking sounds on performance and acoustic satisfaction. Haapakangas et al., Acta Acustica united with Acustica, 2011. Filtered pink noise, ventilation noise, music, and water, each laid over speech. Steady maskers beat music; spring water was the best of the set, with filtered pink noise close behind on satisfaction.
• Unmasking the effects of masking on performance. Keus van de Poll et al., Journal of the Acoustical Society of America, 2015. A single voice hurt short-term memory relative to silence. Masking that voice with several other voices brought performance back to the silent level. Broadband noise works, and workers tend to dislike it.
• Auditory distraction by speech: sound masking with speech-shaped stationary noise outperforms −5 dB per octave shaped noise. Journal of the Acoustical Society of America, 2018. The usual office masker falls about 5 dB per octave. A noise shaped like the speech itself masked as well at a 3 dB worse speech-to-noise ratio.
• The effects of masking sound and signal-to-noise ratio on work performance in Chinese open-plan offices. Applied Acoustics, 2021. Speech-like pink noise, air-conditioning noise, water, and babble, each at three signal-to-noise ratios. Both the masker and the ratio changed performance and annoyance.

Focus when nothing else is playing

• Stimulus-dependent dopamine release in attention-deficit/hyperactivity disorder. Sikström and Söderlund, Psychological Review, 2007. The moderate-brain-arousal model: too little stimulation and too much both hurt, and stochastic resonance is why a moderate noise can help.
• Listen to the noise: noise is beneficial for cognitive performance in ADHD. Söderlund, Sikström, and Smart, Journal of Child Psychology and Psychiatry, 2007. White noise versus silence. Performance rose in the ADHD group and fell in controls.
• The effects of background white noise on memory performance in inattentive school children. Söderlund et al., Behavioral and Brain Functions, 2010. White noise at 78 dB helped inattentive children and hurt attentive ones.
• Different effects of adding white noise on cognitive performance of sub-, normal and super-attentive school children. Helps, Bamford, Sonuga-Barke, and Söderlund, PLOS ONE, 2014. Moderate white noise helped sub-attentive children on executive tasks and hurt super-attentive children.
• Neuropsychological and neurophysiological benefits from white noise in children with and without ADHD. Baijot et al., Behavioral and Brain Functions, 2016. White noise cut omission errors in children with ADHD. The children who benefited also showed a larger Go P300.
• Comparing auditory noise treatment with stimulant medication on cognitive task performance in children with ADHD. Söderlund et al., Frontiers in Psychology, 2016. A small pilot: white noise improved span-board and word-recall performance in children with ADHD, with or without stimulant medication.
• Systematic review and meta-analysis: do white noise or pink noise help with task performance in youth with ADHD or elevated attention problems? Nigg et al., Journal of the American Academy of Child & Adolescent Psychiatry, 2024. Thirteen studies, 335 participants. White and pink noise gave a small benefit (g = 0.25) on laboratory attention tasks for ADHD or high ADHD symptoms, and a small cost (g = −0.21) in comparison groups. No brown-noise study met the criteria.
• Spectral content (colour) of noise exposure affects work efficiency. Lu, Huang, and Lin, Noise & Health, 2020. Twenty-two students, quiet versus white, pink, and red noise. Their red noise is 1/f², a 6 dB-per-octave fall, which is brown noise. Level was only about 47 dBA against a 44 dBA room, so this is mostly an additive test. All three colors beat quiet on psychomotor speed and executive function; only pink did so on continuous performance. The sample is small.
• Stochastic resonance is not required for pink noise to have beneficial effects on ADHD-related performance. Neuropsychologia, 2024. In adults with varying ADHD traits, both pink noise and a pure 100 Hz tone improved a slow reaction-time task. Randomness of the sound was not necessary.
• Pink noise and a pure tone both reduce 1/f neural noise in adults with elevated ADHD traits. Rijmen et al., Journal of Attention Disorders, 2026. Resting EEG. Pink noise and a pure tone changed the aperiodic slope in the same direction, which argues against the stochastic-resonance account in the moderate-brain-arousal model.
• Effects of additive sensory noise on cognition. Sherman et al., Frontiers in Human Neuroscience, 2023. Added white noise did not improve cognition across the whole sample. The effect depended on the person.
• The effect of moderate broadband noise on cognitive performance: a systematic review. Cognition, Technology & Work, 2024. Forty-three studies of moderate broadband noise, mostly white, a few pink. Little evidence of a general harm, and little evidence of a general benefit. Attention tasks were usually unchanged.

One further negative result on the colors themselves: pupil-linked arousal does not differ between white, pink, and brown noise. Chait, International Journal of Psychophysiology, 2025. In naive listeners, ten seconds of each color did not change pupil size.