How Does Sound Masking Work? The Science Behind Sleep Sounds
1. Introduction + At a Glance
Have you ever noticed that the quieter your room is at night, the more noticeable your partner’s snoring or the traffic outside becomes? Yet when you turn on a fan or play gentle rain sounds, those noises seem less bothersome. That is sound masking at work. It does not actually make snoring or traffic noise disappear. Instead, it uses another sound to make them stand out less. But not just any sound will produce the desired effect. The type and volume of the masking sound, as well as the noise you are trying to mask, all affect the result.
[1]
2. How Does Sound Masking Work?
Think of sound masking this way: a black dot stands out on a blank sheet of white paper, but the same dot becomes harder to notice on a sheet covered in patterns. Our hearing works in a similar way. When two sounds occur at the same time, one may make the other harder to detect, especially when their frequencies are close or overlap. This masking of sounds that occur at the same time is called simultaneous masking, and frequency overlap is an important factor in its strength. It raises the minimum sound level needed for us to detect a sound, also known as the auditory detection threshold. [1]
3. What Makes Sound Masking More Effective?
Sound masking is not simply about using a louder sound to cover a quieter one. Its effectiveness depends mainly on three factors:
Sound Frequency: Masking is usually more pronounced when the masking sound and the target noise have similar frequencies or overlapping frequency ranges. For example, deep brown noise may be better suited to masking some low-frequency environmental noise. [1][2]
Relative Volume: The volume of the masking sound affects how easily the target noise can be detected, but turning up the volume should not be the only way to pursue stronger masking. WHO notes that volume, listening duration, and frequency of exposure all affect hearing risk. [1][3]
Changes in Sound (Sound Characteristics): Continuous, steady background sound often makes some environmental noises less noticeable, while a door suddenly slamming, a sharp impact, or snoring that varies widely in volume may still be clearly audible. In a 2005 laboratory study, 4 participants completed all three conditions; adding white noise to recordings of ICU noise reduced sleep arousals. The researchers attributed this to the smaller difference between background sound and noise peaks. [4]
It is important to note that sound masking does not actually reduce the sound pressure level of environmental noise and may instead increase overall sound intensity. It changes our perception of the noise, not the noise itself. [1]
4. What Types of Sounds Are Best for Sound Masking?
White noise, pink noise, and brown noise. Although all three are called “noise,” they sound quite different: white noise has a steady hissing quality, pink noise sounds softer, and brown noise has a distinctly deep, rumbling quality. The key to these differences lies in how sound is distributed across frequencies [2]
Put simply, lower-frequency sounds generally have a lower pitch, such as the hum of an air conditioner or a distant engine, while higher-frequency sounds generally have a higher pitch, such as an electronic alert or a faint hiss. Most noises we hear in everyday life do not consist of just one frequency; they combine sounds at many different frequencies. [1]
Figure note: The curves above should be understood as relative power spectral density, not perceived loudness. White noise has the same average power within equal frequency bandwidths; the power spectral density of pink noise and brown noise decreases by approximately 3 dB and 6 dB, respectively, for each octave increase in frequency. The natural sounds shown are listening analogies, and the curves do not represent sleep benefits. [2]
5. How to Use Sound Masking for Better Sleep?
Now that you understand the characteristics of different masking sounds, how can you actually use them for sleep? The key is not to find the loudest masking sound, but to choose a sound that suits your current noise environment and play it at the lowest possible volume.
1. Match the Sound to the Noise
Different environmental noises have different frequency characteristics, so the masking sounds that suit them may also differ. For example, if you are bothered by the low hum of an air conditioner or distant traffic rumble, you can try brown noise, which has more low-frequency content. For neighbors talking, mild snoring, or other sounds that contain a mix of frequencies, you can try white noise, pink noise, or steady rain sounds. [1] [2]
2. Keep the Volume Low and Comfortable
Do not rely solely on turning up the volume to achieve stronger masking. If you keep raising the volume to completely cover snoring, background sound intended to help you sleep may become another source of disturbance. Start at a low volume and adjust it until environmental noise is less noticeable and you feel comfortable. If you only need help falling asleep, you can try setting a shutoff timer. If you play sound all night, consider the actual volume, playback duration, and frequency of exposure together. [3] Do not assume that headphones or low-volume playback will leave your ability to detect important alarms unaffected; test smoke alarms regularly according to the manufacturer’s instructions. [5]
3. Combine Sound Masking with ANC
Sound masking and active noise cancellation (ANC) do not conflict with each other; they can work together.
ANC can reduce some continuous low-frequency noise, such as air conditioner hum or traffic rumble. [6] Sound masking uses background sounds such as rain or brown noise to make the remaining noise less noticeable. [1]
For example, product information published by DUVA lists Hybrid ANC and sleep audio playback among DUVA ONE’s features, allowing these two approaches to be combined. When ANC reduces some of the background noise, users may not need to turn playback volume up as high. WHO also lists well-fitted, noise-canceling headphones as a way to reduce the need to raise the volume. The actual experience still depends on the noise, fit, and settings. [3]
6. Frequently Asked Questions About Sound Masking
Q1. Does Sound Masking Really Help You Sleep?
Sound masking may help people who are easily disturbed by environmental noise, but making noise less noticeable does not necessarily mean better sleep. A systematic review published by Riedy and colleagues in 2021 included 38 studies and found results ranging from improved sleep to disrupted sleep. The overall quality of evidence supporting continuous noise for improving sleep was rated very low (GRADE: very low). [7] A 2026 laboratory crossover study involving 25 healthy adults found that playing pink noise at 50 dBA throughout the night reduced REM sleep compared with a quiet control condition. [8] These findings cannot be directly generalized to all sounds, headphones, or populations, but they show that sound masking cannot guarantee better sleep for everyone.
Q2. Can Sound Masking Completely Block Out Snoring?
There is no guarantee. Snoring may contain a range of frequencies, and its frequency spectrum can differ by type. In 2008, Herzog and colleagues analyzed simulated and nighttime snoring in 50 men and found different frequency distributions for different types of snoring. [9] It is therefore difficult to guarantee that a single, fixed background sound will completely mask snoring. You can try good passive noise isolation and, depending on the device’s features, combine it with ANC or low-volume masking sound. This is a suggestion to try based on acoustic principles, not a headphone effect verified by that study. [1] [6]
Q3. Is Brown Noise Better Than White Noise for Sleep?
Not necessarily. White noise has the same average power within equal frequency bandwidths, while brown noise has more prominent low-frequency content, so they may perform differently when masking different noises. [1] [2] But a difference in frequency spectrum does not directly prove that brown noise is better for sleep. Findings from studies of continuous background sound are inconsistent. The systematic review cited here is not a direct comparison of brown noise and white noise, so it cannot establish a universally applicable ranking of their sleep benefits. [7] Consider both the actual masking effect and your personal comfort when choosing.
Q4. Is It Safe to Listen to White Noise All Night?
Sounding comfortable is not enough to determine that all-night playback is safe. WHO notes that hearing risk depends on actual volume, listening duration, and frequency of exposure together. Start at a low volume; if you only need help falling asleep, you can try a shutoff timer. Avoid continually raising the volume in an attempt to completely cover environmental sounds. [3] During use, do not assume that important alarms will remain audible, and test smoke alarms regularly according to the manufacturer’s instructions. [5]
Q5. Can Sound Masking and ANC Work Together?
Yes, and the two technologies work differently. Active noise cancellation (ANC) uses opposing sound waves to reduce some of the noise reaching the ears, while sound masking uses background sound to make the remaining noise less noticeable. For example, ANC can reduce some air conditioner hum or traffic rumble. Adding low-volume rain sounds or brown noise may then make disruptive sounds in the sleep environment harder to notice. [6] [1]
References
[1] National Research Council. (2005). Basics of Sound, the Ear, and Hearing. In Hearing Loss: Determining Eligibility for Social Security Benefits, pp. 42–68. National Academies Press. DOI: 10.17226/11099. Cited pages: 43–44, 50–52.
[2] MathWorks. Colored Noise — Generate colored noise signal. DSP System Toolbox documentation.
[3] World Health Organization. (2026, March 6). Deafness and hearing loss: Safe listening.
[4] Stanchina, M. L., Abu-Hijleh, M., Chaudhry, B. K., Carlisle, C. C., & Millman, R. P. (2005). The influence of white noise on sleep in subjects exposed to ICU noise. Sleep Medicine, 6(5), 423–428. DOI: 10.1016/j.sleep.2004.12.004.
[5] National Fire Protection Association. Smoke Alarms.
[6] IEEE Technology Navigator. Active noise reduction.
[7] Riedy, S. M., Smith, M. G., Rocha, S., & Basner, M. (2021). Noise as a sleep aid: A systematic review. Sleep Medicine Reviews, 55, 101385. DOI: 10.1016/j.smrv.2020.101385.
[8] Basner, M., et al. (2026). Efficacy of pink noise and earplugs for mitigating the effects of intermittent environmental noise exposure on sleep. SLEEP, 49(5), zsag001. DOI: 10.1093/sleep/zsag001.
[9] Herzog, M., et al. (2008). Frequency analysis of snoring sounds during simulated and nocturnal snoring. European Archives of Oto-Rhino-Laryngology, 265, 1553–1562. DOI: 10.1007/s00405-008-0700-2.