You've probably heard of white noise. But pink noise? Brown noise? They sound like paint swatches, but they're actually different types of sound — and each one affects your baby's sleep differently. Here's the simple explanation, without the audio engineering degree. Also read our guide on whether white noise helps and our decibel safety breakdown.
White noise plays all sound frequencies at equal volume — high, mid, and low all at once. It sounds like: TV static, a vacuum cleaner, a loud fan, or the classic "shhhh" sound. This is what most baby sound machines produce. It's effective because it masks a wide range of household noises — doorbells, dogs barking, older siblings — all at once.
Pink noise reduces higher frequencies and boosts lower ones. It sounds like: steady rainfall, a heartbeat, wind through trees, or ocean waves. It's softer and more natural than white noise — less "harsh" to adult ears. Some parents find their babies settle faster with pink noise because it more closely mimics the muffled, rhythmic sounds of the womb.
Brown noise goes even deeper than pink — it drops high frequencies dramatically and emphasises the lowest bass tones. It sounds like: distant thunder, a waterfall, or the low roar of a plane cabin. Few baby machines include true brown noise, but it's growing in popularity because it blocks low-frequency disruptions like traffic or construction noise.
| White Noise | Pink Noise | Brown Noise | |
|---|---|---|---|
| Sound like | TV static, vacuum, shush | Rainfall, heartbeat, waves | Thunder, waterfall, deep roar |
| Frequency | All equal | More bass, less treble | Deep bass, very little treble |
| Feels | Bright, sharp, constant | Soft, rhythmic, natural | Deep, rumbling, heavy |
| Best for | Masking sudden household noises | Babies who startle at harsh sounds | Blocking traffic or construction |
| Womb-like? | Closest to womb whoosh | Similar but softer | Less womb-like, more nature-like |
| Common in machines? | ✅ Almost all | ⚠️ Some models | ❌ Rare |
There's no formal study comparing babies' preference for noise colours, but paediatric sleep consultants consistently observe two patterns:
Try this: If you have a machine with multiple sounds, test white noise one night, pink noise the next. Keep the volume and distance the same for both. Most parents know within 2–3 nights which one works better.
Not all machines offer multiple noise colours. Here's what's available in Australia:
See our full comparison of white noise machines for sound options on every model.
Yes — it's safe and often better than turning it off. Here's why: white noise masks sudden sounds. If your baby falls asleep with it on and it stops at 2am, a passing car or creaking floorboard can wake them. Continuous sound means continuous masking. Just keep the volume at 50 dB or below at the cot, and the machine 2 metres away. Read our full decibel safety guide for the exact numbers.
White noise is the most studied and commonly recommended. It mimics the womb's whoosh most closely and masks household noise effectively. If white noise sounds too harsh to you (or your baby startles at it), pink noise is a softer alternative. Start with white, then experiment — there's no wrong answer.
Yes. It's safe and often preferred because babies can wake when it stops. Keep the volume at or below 50 dB at the cot and the machine 2 metres away. Red Nose Australia's guidelines focus on safe distance and volume, not duration.
White noise is the most popular for baby sleep due to its broad frequency coverage. Pink noise is preferred by many adults for deeper sleep and may work better for older babies sensitive to higher frequencies. Brown noise helps if low-frequency noises (traffic, thunder) are the main disruption.
We tested 6 white noise machines in Australia — including models with white, pink, and brown noise options.
See Best White Noise Machines →