Putting it into layman’s terms, white noise is a sound signal which can be best described as flat or neutral sounding. It’s commonly used to help drown out sounds which might otherwise prevent you from falling asleep, or mask sounds that might subconsciously disturb you while asleep. So how does white noise work?
The term “white noise” is more of a general description for a constant, unchanging background noise. A sort of a “shhhhh” type noise.
If you are old enough to remember, it’s the same noise as that made by a television set years ago when the last program had finished for the evening and all that was left was the fuzzy blue or grey screen after the presenter had bid you goodnight.
So many people would fall asleep to that sound and then wake up at 3.00 in the morning only because they were cold or uncomfortable.
But white noise doesn’t have to be that monotone level sound made by the television just before ET lands in your back garden and tries to abduct you. It can in fact be any of a diverse range of sounds including:
- Sounds from nature such as the lapping sea or waves, crickets chirping, forest sounds and so on.
- Mechanical noises like the humming of air conditioning and desktop fans, or the spinning of a washing machine on it’s drying cycle
- Even surround sounds like the chatter of a crowd or the drone of being inside an airplane.
In fact, it’s amazing how many mothers put new born babies in the kitchen or utility room to fall asleep while the washing machine is on. It works like a miracle…
The point is that a monotonous flat sound, although louder than other surrounding sounds gives something for the mind to latch on to and relax, rather than being in alert mode and jumping into action whenever a different pitched sound comes into range.
There are other colours in the noise spectrum apart from white including red, violet, grey and brown. The different colours represent a specific spectral density and they have numerous uses within acoustics, engineering and physics.
Pink noise for example has been studied as another potential sleep aid with some promising results as it’s not as sharp and crackly as pure white noise.
How does white noise work as a sleep aid?
The idea of adding more noise in your bedroom to help you sleep may sound counter-intuitive, but it works because white noise smooths the surrounding and external sounds such as traffic or a dog barking in the distance into the overall background noise. The result being that your mind pays less attention.
According to neuroscientist Seth S. Horowitz, our hearing has evolved as an alarm system, and it works even when we’re asleep. We become habituated to most background sounds unless they flag up on our cognitive radar as being worthy of attention.
It’s not necessarily the volume that keeps us awake but the context of the sound. That’s why (other than being totally intoxicated) it’s possible for some people to fall asleep in the middle of a noisy nightclub, whereas a noise in the distance (such as our barking dog again) can create a response from the mind even when we’re in deep sleep mode.
It’s all about masking the noise
When you add white noise to your sleep area, you’re effectively masking the surrounding sound. Instead of drowning out the sounds, they become ‘masked’ by the frequencies generated by the white noise signal.
Using light as an analogy.
Imagine being in a darkened room and switching on a flashlight. The light is pretty obvious immediately.
However, imagine that the room was already brilliantly lit, the flashlight would hardly be noticeable because it has been “masked” by the brighter surrounding light.
This is the effect of masking noise.
What other uses are there apart from sleep?
Tinnitus is a very disturbing hearing disorder that causes continual ringing noises in the ears.
Sufferers have often reported that the use of a white noise machine in the bedroom at sleep time can significantly aid falling asleep and staying asleep.
Again, the same principles are at work. Mask the continual surrounding sound by a noise frequency that blends everything out.
In the office.
The continual noise of chitter chatter in an office, along with the constant whirring noise of printers and photocopiers can be a major source of distraction for a lot of people.
The use of screening to deaden sounds along with a white noise machine can help to combat distraction, reduce stress and tension and make an office more productive and pleasurable.
Can music be used to help sleep instead of white noise?
Extensive studies have been carried out into the properties of music as an aid for sleep, and music has been shown to be effective in improving sleep quality.
However, it’s not for everybody.
While music can be soothing and stimulate emotional responses, the range of frequencies in music isn’t wide enough to blend and mask all sounds. In fact, music can be counter active as it can promote memories and emotional responses which the brain may react to and become alert.
At best, music should be regarded as a pleasant form of relaxation rather than a means to block out other sounds.
Is white noise suitable for babies and baby sleep patterns?
As humans we are pre-programmed to only a small number of fears. Two of them being the fear of falling, and the fear of loud noise.
They are a survival mechanism that we are gifted with even inside the womb. Every other fear is learned from birth.
Surprisingly, the womb is quite a noisy environment where babies are subject to sounds that can make them jump or flinch, but despite this they are born with an immature nervous system and unregulated body clock.
Combine those two attributes and it’s not difficult to see why sleep can be a problem for the first few months of life.
While swaddling is often helpful in calming the startle reflex, it doesn’t mask out all the different sounds in the environment.
Interestingly enough, we may have a natural affinity with white noise and calming babies. As mentioned earlier, the sound of white noise is very similar to a ‘Shusssh’ type noise which is exactly the same sound we automatically use to calm a baby or child.
Is white noise harmful for either a baby or adult?
There have been many studies carried out over the last 15-20 years with a lot of them available to review on the internet. However, it seems fairly inconclusive with opinion being more weighted on the side of white noise being beneficial for babies struggling to sleep and those with sleep disorders or tinnitus for example.
One small study in 2014 titled ‘Infant Sleep Machines and Hazardous Sound Pressure Levels‘ looked at the effect of sound machines on the health of sleeping infants.
The main recommendation was that babies should not be exposed to white noise sound machines above a volume level of 85dB (equivalent to the noise of a hairdryer) for more than 8 hours.
It also recommended that sound machines should be placed away from the crib, not next to your baby, which all makes perfect sense.
Additionally, a baby’s brain needs stimulation in order to develop and some reports have suggested that over use of white noise may limit the range of sounds the baby gets to hear, which was born out by a related study on the effect of white noise on the brain development of young rats.
There doesn’t appear to be any concrete evidence that the use of white noise machines are harmful to an adult or infant, and in fact some reports say that it can be very beneficial in treating certain sleep, hearing or anxiety disorders.
Like most treatments though, you need to know when enough is enough.
So the important points to remember are:
1) Limit the volume of the sound machine to around 50dB, and certainly no higher than 85dB
2) Don’t place the sound machine next to the crib or bed.
3) Use your sound machine sparingly. This way you will always reap maximum benefit when you need it.