Shushing works because it mimics the constant whooshing sound your baby heard in the womb for nine months. That sound, mostly from blood flowing through the placenta, stopped crying in 86% of newborns in clinical testing and put 30% of them to sleep. The technique is simple, but getting the details right makes a big difference.
Why Shushing Calms Babies
Inside the uterus, your baby was never in silence. The sound of blood rushing through vessels created a constant low-frequency noise, ranging from a few hertz up to about 1,000 hertz. That’s roughly the same frequency range as a sustained “shhhh” sound or a running shower. After birth, especially in the first few months, babies are still wired to respond to these familiar sounds. Hearing something that matches what they experienced in utero triggers what researchers call a calming response: their heart rate drops, their nervous system shifts from a stressed state into a more relaxed one, and fussiness decreases.
This response is strongest in the youngest babies. Newborns are extremely sensitive to womb-like stimuli because their bodies are still transitioning from intrauterine to extrauterine life. By around three to four months, the effect gradually weakens as babies adapt more fully to the outside world. So the window where shushing is most powerful is roughly the first 12 weeks.
How to Shush Effectively
The most common mistake parents make is shushing too quietly. A crying baby can’t hear a gentle “shh” over the sound of their own screaming. To get their attention, your shush needs to be at least as loud as the cry itself. This feels counterintuitive, but babies don’t need silence to calm down. In fact, silence can make them fussier because it’s the opposite of what they’re used to.
Here’s the technique step by step:
- Get close. Bring your mouth within a few inches of your baby’s ear. You don’t need to shush directly into the ear canal, just near it so the sound is clear and present.
- Start loud. Match the intensity of your baby’s cry with a strong, sustained “shhhhhh.” Think of the sound of a running faucet or radio static, not a librarian’s whisper.
- Keep it continuous. A long, steady stream of sound works better than short, clipped shushes. The goal is to replicate a constant background noise, not a rhythmic pattern.
- Taper down. As your baby starts to settle, gradually lower your volume. Let the shush become softer and softer until it fades out or your baby is calm.
Shushing works best when combined with other soothing techniques. Pediatrician Harvey Karp popularized a system called the 5 S’s: swaddling, holding the baby on their side or stomach (in your arms, not for sleep), shushing, gentle swinging or rocking, and offering something to suck on. Each of these recreates a different aspect of the womb environment. Used together, they’re more effective than any single technique alone. You don’t always need all five, but if shushing alone isn’t cutting it, adding swaddling or gentle motion often tips the balance.
White Noise as a Substitute
Your voice will get tired. A white noise machine, a fan, or even a phone app playing static can take over the job once your baby starts to settle. These tools produce the same type of broad-spectrum sound that triggers the calming response. Some machines include a heartbeat setting that mimics the mother’s pulse, which can add another layer of comfort for newborns.
The key difference is that a machine can’t adjust in real time. When your baby is actively screaming, your voice is better because you can match and then gradually reduce the volume. Once they’re winding down, a consistent mechanical sound can maintain the calm while you rest your lungs. Many parents find that running white noise during sleep helps babies stay asleep longer, since it masks sudden household sounds that might startle them awake.
When Shushing Isn’t Working
If your baby seems to cry harder or turns away from you when you shush, they may be overstimulated rather than understimulated. Overstimulated babies show specific signs: they clench their fists, wave their arms and legs frantically, turn their head away from you, or act increasingly irritable despite your efforts. More sound and more touch can actually make things worse in this state.
Babies between about 2 weeks and 4 months go through what’s called the purple crying phase, a period of increased fussiness that peaks around six to eight weeks. During this phase, some babies resist being held or touched when they’re overwhelmed because the physical contact itself is part of the overstimulation. If your baby pulls away or arches their back, try laying them on their back in their crib and sitting quietly nearby. Sometimes reducing all input is more effective than adding more.
It’s also worth noting that shushing addresses discomfort from the transition out of the womb, not from hunger, a dirty diaper, or illness. If the basic needs are met and your baby still won’t settle with any combination of soothing techniques, that’s worth bringing up with your pediatrician, especially if the crying is accompanied by fever, unusual stool, or refusal to eat.
Practical Tips for Tired Parents
Sustained loud shushing is physically exhausting. A few shortcuts can save your energy. First, you can make a “shh” sound on the exhale and inhale, creating a nearly continuous stream without pausing to breathe normally. It takes a little practice but doubles your endurance. Second, once you’ve gotten the initial crying under control with your voice, hand off to a white noise source immediately. Don’t wait until the baby is fully asleep, just until they’ve shifted from active crying to fussing or quiet alertness.
If you’re in public or somewhere you can’t easily shush at full volume, a phone held near the baby playing white noise or shushing sounds at moderate volume can work as a substitute. It won’t be as effective as your voice up close during peak crying, but it’s better than a quiet environment. Running water from a sink or faucet also produces a similar sound profile and can buy you a few minutes of calm in a pinch.