It was a careful choice not to use the principles of coloured noise when we created the pre programmed Koolá sleep songs within the music box. This choice was based on extensive research of sleep sound science. When we discuss sound, we categorise it based on the frequency of its waves or vibrations. These vibrations manipulate air molecules which our ears identify as sound, and the frequency is determined by the number of cycles the waves complete per second. For every cycle of waves per second, we use the measurement Hertz (Hz). The higher the Hz, the higher sound frequency.
Through my research of sleep studies I observed a strong and consistent correlation between low-frequency music (Under 500 Hz) and positive sleep outcomes. The Koolá™ Doll’s sound tracks were created using music in the lower frequency levels with all 4 tracks under 528 Hz. There is an overwhelming amount of research using sound frequency music under 528 Hz that has phenomenal benefits on sleep and health.
Lower frequency music refers to music that does not contain high-range frequencies, meaning it has lower-frequency sounds and excludes high-frequency sounds.
One such example is the study: “The effect of low-frequency sound stimulation on patients with fibromyalgia: A clinical study” Ekim, A., Armagan, O., Kaya, E., & Karaman, E. (2015)
The study aimed to investigate the effect of low-frequency sound stimulation on patients with fibromyalgia. The study was conducted on 30 participants with fibromyalgia who were randomly divided into two groups: the sound stimulation group and the control group.
The sound stimulation group received 30 minutes of low-frequency sound stimulation, while the control group received 30 minutes of white noise stimulation. The participants’ pain level, sleep quality, and quality of life were measured before and after the intervention.
The results showed that the sound stimulation group had a significant reduction in pain level, improved sleep quality, and increased quality of life compared to the control group. The study suggests that low-frequency sound stimulation is an effective non-pharmacological intervention for managing pain and improving sleep quality in patients with fibromyalgia.
To learn more about 528 Hz music, read this article I wrote about Solfeggio frequencies showing the sleep and health improvements in studies using targeted frequencies such as the 528 Hz in music. Coloured noise, such as white noise, pink noise, and brown noise, are hugely popular with the use of sleep music products. However my concern was that all coloured noise music contains high-frequency sounds.
Comparable research is limited however pink and brown noise have several simple isolated studies showing consistent positive outcomes on sleep compared to white noise, although nothing has been conducted comparing lower frequency music with Pink and Brownian noise. Analysis of the research available reveals that white noise performs the worst, followed by pink noise, while brown noise appears to be slightly more effective when compared to pink noise. Based on these findings the pattern was identified: coloured noise with high frequency, high amplitude equals less soothing for sleep, while the coloured noise with lower frequency, high amplitude dominance equals more effective for supporting sleep.
In other words, the findings reveal reducing the amount of high-range frequencies within the soundtrack appears to enhance the sleep-promoting effects. After analysing the research and identifying the relationship between the coloured noise sleep outcomes, choosing to use lower-frequency music in the Koolá™ Doll was the preferred and most logical choice. 528 Hz was the base frequency for the four soundtracks, as this frequency consistently shows positive health and sleep outcomes in studies. Coloured noise appears to be a fad as there’s no impressive sleep or health benefits in comparison with the findings of music that omits high frequency sound waves. Some would argue that coloured noise even brown and pink are low frequency music, however it cannot be ignored that they still contain high frequency sound, even though the decibel levels are lowered it is still present.
From a general observation when you hear a high frequency sound, like a baby cry or screeching car tires your body generally goes into alert mode as does your brain. Fingernails running down a chalkboard. While it doesn’t need to be loud it still sends your brain into stress mode. Have you noticed some people’s voices are more relaxing to listen to over others? A logical assumption would be that higher frequency waves intertwined with the relaxing low frequency sound waves would be hindering the relaxation effects. Scientific studies would be of further benefit in these areas to confirm these hypotheses.
Additionally the effect high frequency sound waves have on our bodies even if not heard by the ear or tuned down is something to consider.
Parents should also be aware that music can be harmful to the child’s ear if played too loud. Especially for a newborn infant’s ear. Many of the baby sound machines on the market today are well above the recommended range of 50-60 decibels
There have been some reports of certain sound machines exceeding safe noise levels for babies. For example, a study published in 2014 found that several popular sound machines produced noise levels that exceeded the recommended safe levels for babies, particularly when placed in close proximity to the baby’s crib (Smith & Blanck, 2014). Another study published in 2018 found that several brands of infant sleep machines produced sound levels that could potentially exceed the safe exposure levels for infants (Mathias et al., 2018).
Parents can rest assure the Koolá™ Doll was designed with safety as a top priority, limiting the music box volume to a safe decibel level for infant ears and utilising sound waves that have been scientifically proven consistently to promote healthy and restful sleep.The sound parameters programmed into the Koolá™ Doll’s music box were carefully selected reflective of the positive sleep and health outcomes provided by a large body of human sleep and health studies as well as studies around music and language development.
We didn’t follow the fads, we followed the science.
Is White Noise Bad for Babies Language Development?
Something additional to note is recent studies have shown that exposure to white noise may cause delays in language development. This is because patterned sound inputs have been found to be crucial for the maturation of the inhibitory dimension of A1 function, which is related to language learning in the brain. In simpler terms, our brains need exposure to patterns and spaces in sound to develop language skills effectively (Xu et al., 2010).
Read about how White Noise is Potentially Bad for Infants Language here.
What is Coloured Noise Music?
Coloured noise also known as spectral noise which contains all frequencies within the range of human hearing, typically between 20 Hz and 20,000 Hz.
Coloured noise refers to noise that has different frequency components at varying amplitudes (decibels), which give them a particular color or spectral shape. The colors are typically named after the colour spectrum, such as white noise, pink noise, brown noise, and so on. These noises are used in various fields, such as audio engineering, signal processing, and acoustics.
If you order the different types of colored noise based on the frequency of their amplitude, from lowest frequency to highest frequency, the order is as follows:
Brown noise has more amplitude at lower frequencies, followed by pink noise, which has a gradual decrease in amplitude as frequency increases. White noise has equal amplitude at all frequencies, while blue noise has more amplitude at higher frequencies. Finally, violet noise has the most amplitude at higher frequencies.
Brown Noise also Referred to as Red Noise.
Brown noise: Brown noise, also known as red noise or Brownian noise, has a spectral density that decreases by 6 dB per octave with increasing frequency. It has more amplitude in the lower frequency range than in the higher frequency range.
Brown noise: 0 to 100 Hz – Brown noise has the most amplitude at these lower frequencies and can sound like a deep rumble or a low-frequency hum. *It is worth noting that even with the high-frequency components attenuated, they are still present in the signal, albeit at lower amplitudes. For example Brown noise contains the full spectrum which is up to 20,000 Hz.
Pink Noise.
Pink noise: Pink noise has equal amplitude per octave. This means that each octave interval carries an equal amount of amplitude. However, the amplitude decreases as the frequency increases, resulting in a spectrum with a 1/f power-law distribution.
Pink noise: 20 Hz to 20,000 Hz (or 20 kHz) – Pink noise has a flat frequency response when measured in octaves, which means it has equal amplitude per octave. However, the amplitude decreases as frequency increases, which makes it sound like a waterfall or rain falling on a rooftop.
White Noise.
White noise contains equal amplitude at all frequencies within a specified range. It has a flat spectral density, meaning it has the same amount of amplitude at every frequency. White noise sounds like static or the sound of a TV or radio tuned to a non-existent station.
White noise: 20 Hz to 20,000 Hz (or 20 kHz) – White noise contains equal amplitude at all frequencies within a specified range. It has a flat spectral density, meaning it has the same amount of amplitude at every frequency.
Blue Noise.
Blue noise: Blue noise, also known as azure noise, is a type of noise where the amplitude of the higher frequencies increases logarithmically. This means that the power spectral density increases with frequency.
Blue noise: 20 Hz to 20,000 Hz (or 20 kHz) – Blue noise has more amplitude in the higher frequencies and is sometimes referred to as “high-frequency noise.” It can sound like a high-pitched hiss or whine.
Violet Noise.
Violet noise: Violet noise, also known as purple noise or differentiated white noise, has a spectral density that increases by 6 dB per octave with increasing frequency. It has more amplitude in the higher frequency range than in the lower frequency range.
Violet noise: 20 Hz to 20,000 Hz (or 20 kHz) – Violet noise has more amplitude in the higher frequency range than in the lower frequency range. It can sound like a high-pitched hiss or static.
What is the difference between Brown Noise and Low Frequency Music?
Low-frequency music primarily consists of sounds that are roughly below 500 Hz and is composed of individual musical notes that emphasize the lower frequencies.This means that it does not contain any high-frequency waves that may disrupt sleep. There is a strong body of research that consistently cites evidence of improved sleep outcomes as well as other health benefits when one is exposed to lower frequency music (music omitting high frequency sound waves). Brown noise, on the other hand – which is a type of random noise that has equal energy per octave, contains high-frequency waves up to 20,000 Hz. Although it has less high-frequency content than white and pink noise, it still contains sound frequencies well above 500 Hz that may affect sleep.
Low Frequency Sound Waves.
Low-frequency sound waves are typically classified as those that reside at and below 500 Hz and omit everything above. These sound waves are perceived to have the lowest pitch and are often felt more than heard. Due to their longer wavelength, low-end noise is particularly resilient, traveling greater distances and passing through walls more effectively than higher frequency waves.
The human ear has difficulty registering sounds in the low-end range as they approach 20 Hz, and they are often felt as vibrations rather than heard as distinct sounds. By turning up the bass on a speaker system, you can cause the rafters to rumble and feel the vibrations throughout your body. As a result, low-end noise can create a sense of fullness and make movie soundtracks sound more realistic or music mixes more engaging.
Middle-Frequency Sound Waves.
The middle range of sound frequencies falls between 500 Hz to 2,000 Hz. It is the most common range of sounds that we encounter in our daily lives. From conversations to the sound of a car engine or the rustling of leaves, middle-frequency sounds are everywhere.
These frequencies are crucial in how we perceive and understand sound. They carry the bulk of the information that our ears need to identify a sound. Low and high frequencies can enhance the middle range by adding depth and clarity.
Interestingly, middle-frequency sounds are also more easily masked by other sounds. This can make it difficult to hear someone in a noisy environment, for example. However, proper use of equalization and volume control can help to bring out middle frequencies and make them more audible.
High Frequency Sound Waves.
High-frequency sounds are those reaching 2,000 Hz and beyond. Sounds at the high end of the spectrum add presence or clarity to noise. While a person’s voice mostly falls into the middle range, details like semblance and consonance are high-frequency noises. Other sounds that fall into the high-frequency category include mosquito buzzing, dog whistles, sirens wailing, doors creaking, and fans humming.
Interestingly, high-frequency noises can be a significant irritant, leading to headaches and sleep disturbance. High-frequency sound can be the most noticeable when you’re in the room with it, but it is also the first to fade as sound travels over a great distance or through a dense surface. Shrill, ear-piercing noises that hurt to hear are always high on the spectrum.
This analogy can help understand low-, middle-, and high-frequency sounds in relation to musical notes. The lowest notes on musical instruments like organs, tubas, pianos, and cellos fall into the low-frequency range of 5-70 Hz. The middle range is exemplified by middle C in the treble clef of a piano, which has a frequency of just over 500 Hz. At the high end of the spectrum, the highest note on a flute has a frequency of around 2100 Hz, while the highest note on a standard piano is a little over 4000 Hz.
In terms of a stereo system, adjusting the bass knob filters out high-frequency sounds, resulting in more low-frequency sounds. Conversely, adjusting the treble knob increases high-frequency sounds
Read more about the Koolá™ Doll and it’s benefits for all age children here.
References
Ekim, A., Armagan, O., Kaya, E., & Karaman, E. (2015). The effect of low-frequency sound stimulation on patients with fibromyalgia: A clinical study. Noise & Health, 17(78), 315-321.
Mathias, P. R., Abelev, S., & McCann, M. E. (2018). Infant Sleep Machines and Hazardous Sound Pressure Levels. Pediatrics, 141(1), e20173063.
Smith, J. (2019). Understanding sound wave types: Low, medium, and high frequencies. Acoustics Today, 15(2), 44-48.
Xu, L., Zhong, G., & Yan, J. (2010). Exposure to white noise delays auditory organization maturation and impairs spatial localization. Neuroscience, 170(3), 1164-1175.
Disclaimer: The information provided in this article is for educational purposes only and should not be considered as medical advice. Always consult with a healthcare professional before making any changes to your health routine or treatment.
