Some people are lucky, they can sleep through a tornado, but most of us struggle to fall asleep in a noisy environment. So what do you do if your neighbour’s dog insists on barking all night or traffic noise keeps you awake? If that’s the case you might want to consider trying out white noise.

What is white noise?

In simple terms, white noise is a special type of sound signal which is used to mask background sounds. When used to promote healthy sleep, white noise helps to drown out sounds which might otherwise prevent you from either falling asleep or waking up whilst asleep.

In technical terms white noise can be described as noise whose amplitude is constant throughout the audible frequency range.

White light

White noise, like white light, consists of all frequencies combined together

A useful analogy is that of white light, which as we all know from school, contains all the colours (frequencies) combined together.

White noise theory has it’s origins in mathematics and engineering and these days it has applications in fields as diverse as acoustics, electronics, computer programming and even economics. If you want to delve deeper, Wikipedia which has an excellent resource on the science of white noise.

What does white noise sound like?

Click below to play a sample of white noise. Caution: Do not play loud if wearing earphones

Genuine white noise can only be generated electronically and sounds similar to TV or radio ‘static’. It is not very pleasant on the ears as it contains a lot of high frequency energy. 

Other types of ‘white noise’ sounds

Sometimes “white noise” is used as a general description for any type of constant, unchanging background noise. It’s become a colloquial term for a diverse range of sounds including:

  • nature sounds – rain, sea/waves, crickets chirping, jungle etc
  • machinery noises – air conditioning units, washing machine
  • ambient soundscapes – aircraft interior, crackling campfire, crowd noise
Some people prefer to listen to these types of sounds when they’re trying to get to sleep in preference to the harsh tone of pure white noise.

Incidentally, there are many other ‘colours of noise‘ including red, brown, violet and grey, to name a few. The different colours represent a specific spectral density and they have various applications in acoustics, engineering and physics. One such variant, pink noise, has been studied as a potential sleep aid with some promising results. ((Pink noise: Effect on complexity synchronization of brain activity and sleep consolidation Junhong Zhoua, Dongdong Liub, Xin Li b, Jing Mac, Jue Zhanga, Jing Fang. Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People’s Republic of China, College of Engineering, Peking University, Beijing 100871, People’s Republic of China, Department of pulmonary, Peking University First Hospital, Beijing 100034, People’s Republic of China))

How does white noise work?

The idea of adding more noise in your bedroom to help you sleep may sound counter intuitive, but it works because white noise blends the external sounds (barking dog,traffic etc) into the overall background noise, so your brain 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 the context of the sound, not necessarily the volume that keeps us awake. That’s why it’s possible for some people to fall asleep in the middle of a noisy nightclub. In the same way, a distant barking dog can set off a startle response even when we’re unconscious and asleep.

Masking the noise

When you add white noise (or a similar sound) to your sleeping environment, you’re utilising a principal known as sound masking. Rather than drowning out the offending sounds, they become ‘masked’ by the frequencies of the white noise signal. We can use light again as an analogy.

Imagine being in a dark room and you switch on a flashlight. You immediately notice the light source. But what if the room is already brightly lit? The flashlight is now barely noticeable because it has been “masked” by the brighter room lights.

analogy of light - sound masking

Sound masking – an analogy with light

As well as helping you get to sleep, sound masking is used extensively in offices to reduce the effect of distracting conversations and also in treating tinnitus, a hearing disorder that causes a constant ringing in the ears.

Can you use music instead of white noise to help you sleep?

The sleep promoting qualities of music have been extensively studied, and indeed music has been shown to be effective in improving sleep quality. ((Music-assisted relaxation to improve sleep quality: meta-analysis. de Niet G, Tiemens B, Lendemeijer B, Hutschemaekers G. Gelderse Roos Mental Health Care, Institute for Professionalization, Wolfheze, The Netherlands.)) However, music doesn’t contain the wide range of frequencies that are needed to mask intrusive sounds, so it’s less effective than white noise in this respect. Music can also stimulate emotional responses, memories and other associations which may prove counteract your sleep promoting efforts. Music is probably more suited for relaxation rather than as a means to ‘block out’ other sounds.

Babies and white noise

All newborns start with an ‘untrained’ sleep/wake cycle. Over the first few months, babies start to adjust to the natural transition of day and night. The holy grail is to get the baby ‘sleeping through the night’. But no two babies are the same and sometimes sleep training or ‘crying it out’ leads nowhere. In these circumstances many parents turn to white noise as a baby sleep solution.

Even before they’re born, babies are quite used to loud noises. The womb, is a surprisingly noisy environment. However, all  babies have an immature nervous system which makes them especially ‘jumpy’. The ‘moro reflex‘ causes them to physically flinch when they are startled by a loud noise or loss of support. Swaddling can help stifle the physical effects of this reflex, but if sleep problems persist, white noise could provide some help.

White noise is not unlike the instinctive ‘shhhush’-ing sound parents make when trying to comfort or quieten their child. It masks any sounds which might otherwise startle the infant. Babies have sensitive hearing so it’s best to keep the volume to a conversation level.

It’s a good idea to limit the baby’s exposure to white noise. A infant brain needs stimulation in order to develop properly and over reliance on white noise may limit the range of sounds the baby gets to hear.

Ways to use white noise for sleep

Far from being limited, white noise solutions come in many shapes and sizes. From state of the art ‘sleep sound systems’ to low-tech zero-budget options, you’re spoilt for choice. Here’s our rundown of some of the most popular solutions:

Sleep sound machines/white noise machines/sound conditioners

One of the easiest ways to enjoy white noise is with a standalone sound machine. They are a great option for people who like simple, push button functionality and don’t want to tie up a CD player or computer for playback device. Manufacturers choose not to use the term “white noise machine” as modern gadgets tend to offer a range of electronic and pre-recorded sounds for you to choose from. There’s a dizzying array of machines to choose from. These are some of the most popular devices currently on the market.

Marpac Dohm Sleepmate 980A Sound Conitioner

Marpac has been making sound conditioners for over 50 years

Marpac is the grand-daddy of white noise machines. The Marpac Dohm (formerly known as the Sleepmate/Sound Screen 980A) is a variant of a design that has been around for over 50 years. Marpac describe the Dohm as a ‘sound conditioner‘ rather than a white noise machine.

It’s the only device that uses a mechanical element rather than electronics – the noise is generated by a whirring internal fan. You can change the tone by adjusting air vents on the side. Despite the lack of features, the Dohm is still going strong after all these years. The, ‘if it aint broke’  approach has won the Marpac Dohm a lot of supporters over the years and it’s recognized as the Official Sound Conditioner of the National Sleep Foundation.

Adaptive Sound Technologies (ASM) uses patented technology to generate relaxing soundscapes on the fly, eliminating repetition by blending lengthy, naturally recorded, high-definition sounds together. Their range of sleep sound machines include the  Sound+Sleep ( aka Ecotones ASM1002) and the Nomad. These devices also have an intelligent feature which automatically adjusts the volume in response to ambient sounds like coughing or snoring in the bedroom.

HoMedics makes a range of health and wellness products including sound machines for sleep, relaxation and mediation. The HoMedics SS-3000 Soundspa Lullaby is a sound machine for babies and children that includes a small night time projector which beams images onto the ceiling to accompany

Sound Oasis have been making a range of sleep sound therapy systems since 1993.  The Sound Oasis Sound Therapy System uses built in sounds such as Ocean Surf, Stream, Rain as well as a traditional white noise setting. Sound Oasis have an extensive expansion card library where you can add to the range of sounds for specific needs including baby sleep, tinnitus therapy or mechanical sounds.

Conair makes a range of no frill sound machines for those on a budget. The Conair SU1W offers 10 built in sounds including White noise, Waterfall and a Heartbeat setting. You get a timer and a nightlight, but that’s about it for the feature set. However, it’s one of few reputable sound machines on the market that you can get hold of for less than $20.

White noise solutions for free

You don’t necessarily have to spend any money at all if you want to try white noise as a sleep solution. Here are some tips that won’t cost you a penny.

  1. Use an old radio/boom-box – anything with an FM tuner should suffice. Just dial in between stations (or break the antenna) and you’ll have a perfectly good approximation of pink noise. We don’t recommend using TV as a source as the flickering light can have a detrimental effect on sleep quality
  2. Use a fan – the whirr of a standard desk fan can be ideal for sound masking
  3. Use free white noise MP3s – there are loads of places you can get free white noise and nature sound MP3’s. You’ll still need something to play the MP3s back -but any computer or mobile phone should suffice. Here are a couple of Sleep Junkies recommendations for making your own sleep sound track:
  • http://naturesoundsfor.me/ – mix and download your own custom sleep sound track. Over 50 different source sounds including Pink noise, nature sounds animals and even Darth Vader.
  • http://archive.org/details/opensource_audio – a huge open-source (free) sound library with over 1 million downloadable clips. Just use the search engine at the top of the page and type “white noise” (or whatever you like)

White noise apps

One of the easiest ways to ways to try white noise is with a smartphone. If you’ve already got an Android device or iPhone, there are countless free and paid apps designed to help improve your sleep. The main advantage of using a white noise app is convenience. Many people already keep their phones by the bedside, so there’s no extra equipment to worry about.

One the negative side, some of the free apps use low quality sounds that might be more annoying than soothing. In addition, you’re not going to get the best sound quality with just your phone speaker. All this taken into account, white noise apps are a very popular way to get to sleep. Here are a couple of the most popular cross platform white noise and sleep apps available for iOS, Android, Blackberry and Windows

White Noise by TMSoft (free/premium). With a recommendation by the TV celeb Dr Oz this is currently the most popular white noise app on the market. There’s over 40 sounds to choose from plus you have the ability to create your own playlists by mixing sounds together.

Relax Melodies by Ipnos Soft (free/premium) You get over 88 high quality sounds plus 6 binaural beats to use for “brainwave entrainment”.

Is white noise harmful?

No long-term studies have been made on the effects that white noise has on humans. Fortunately most of the research in this field has so far produced positive results. One study looked at noise disturbances in intensive care units (ICU) and found that episodes of wakefulness were reduced when the ICU noise was mixed with white noise. ((The influence of white noise on sleep in subjects exposed to ICU noise. Stanchina ML, Abu-Hijleh M, Chaudhry BK, Carlisle CC, Millman RP. Sleep Med. 2005 Sep;6(5):423-8. Epub 2005 Mar 31.))

Another study, although unrelated to sleep, showed that white noise proved beneficial in improving concentration and cognitive performance in ADHD patients. ((Listen to the noise: noise is beneficial for cognitive performance in ADHD. Söderlund G, Sikström S, Smart A. Department of Psychology, Stockholm University, Sweden.))

You’ll also find a lot of anecdotal evidence of parents having success with white noise for babies and infants and some small scale studies ((White noise and sleep induction. J A Spencer, D J Moran, A Lee, and D Talbert Arch Dis Child. 1990 January; 65(1): 135–137.)) have yielded some positive results.  However some scientists has suggested that excessive white noise exposure may delay infant brain development . Occasional use of white noise for babies most likely will not cause lasting detrimental effects, however you should always consult your paediatrician if you have any concerns.

Photo by jDevaun.Photography 

Jeff Mann is the founder and editor of Sleep Junkies. You can reach me at jeff (at) sleep junkies (dot) com
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