Not all noise is the same. In acoustics, different "colours" of noise refer to the way energy is distributed across the frequency spectrum. Just as white light contains all colours of the visible spectrum, white noise contains all audible frequencies at equal intensity. Other noise colours emphasise different parts of the spectrum, and each produces distinct effects on the listener.
What makes coloured noise so effective for wellness is its consistency. Unlike music or speech, which constantly changes in pitch, rhythm and volume, noise provides a steady, unchanging sonic backdrop. This consistency gives the brain something stable to anchor to, which is why noise is so widely used for sleep support, focus enhancement and tinnitus relief.
The compositions on WOU Frequency Music™ blend each noise type with musical elements - piano, harp, flute, jazz and nature sounds - creating a listening experience that carries the therapeutic benefits of the noise while remaining musically engaging and enjoyable.
Pink Noise resembles the sound of steady rainfall or a distant waterfall. It emphasises lower frequencies, producing a warm, balanced sound. Pink noise has been studied for its effects on sleep quality and memory consolidation, with research showing that it can promote more stable deep sleep and reduce mental fatigue. It also helps quieten internal mental chatter, making it effective for both rest and concentration.
Brown Noise is deeper and richer than pink noise, with a strong emphasis on low frequencies. Think of thunder rumbling in the distance or the deep roar of a strong wind. Brown noise is particularly effective for relaxation and stress reduction, producing a physiologically calming effect. It is also useful for masking low-frequency environmental sounds that other noise types may not cover effectively.
Blue Noise sits at the opposite end of the spectrum, emphasising higher frequencies. It has a bright, crisp quality - like the hiss of a fine water spray. Blue noise can promote increased alertness and is sometimes used for focus tasks that require sustained attention. It has also been noted for providing relief from tinnitus.
Green Noise sits in the mid-frequency range and closely mimics the ambient sounds found in nature - rustling leaves, gentle breezes and flowing water. It triggers a biophilic response, a deeply rooted human connection to natural environments. Green noise has been associated with reduced cortisol levels, non-intrusive focus support, and promoting restful sleep.
Grey Noise is perceptually balanced so that all frequencies sound equally loud to the human ear (unlike white noise, which can sound harsh at high frequencies). This makes it particularly soothing and is why grey noise is widely recommended for tinnitus relief and management. It promotes relaxation and can support both sleep and focused work.
White Noise contains all frequencies at equal power and is the most widely known noise type. It produces a consistent, full-spectrum sound that is effective for masking a wide range of environmental disturbances. The Babies series on WOU Frequency Music™ features white noise compositions that mimic the familiar sounds of the mother's womb, which babies respond to instinctively.
Each person responds differently to the various noise types, and discovering which one resonates best with you is part of the experience. For sleep, pink and brown noise are generally the most popular choices - their warmer, lower frequencies tend to feel more enveloping and soothing. For work and study, blue and green noise often support alertness and focus without creating agitation. Grey noise is well suited for tinnitus relief and general relaxation.
There is no single correct choice. Many listeners find that different noise types serve them best at different times of day or for different activities. The beauty of having all six noise types available is the ability to experiment and build a personal understanding of which colours of noise support your specific needs.
Listen to 30-second previews of all our Pink, Brown, Blue, Green, Grey, White Noise tracks with a free account, or subscribe for full access.