White, Brown, Pink – The Different Colors Of Noise
If you own a sound machine or you’re currently looking to purchase one, you’ve probably noticed that most of them offer white, pink and brown noise options. You may also encounter in physics, audio engineering and many other fields. Just like different wavelengths of visible light form the color spectrum, colors have been assigned to noise based on the frequency of the sound wave. Let’s take a look at how the colored noises differ from each other and how they can be used.
Different sounds are distinguished from each other by means of spectral density, which is a statistical feature referring to the distribution of power in the frequency spectrum. Different spectral densities have been given different color names. The most common colors of noise that you will hear about include white, pink, gray, black, violet, blue and brown.
White noise is the one whose frequency spectrum is flat since it comprises of equal energy per cycle. The reason that the color white has been given to this type of noise is that the same power is found in every band of signal between 20 and 40 Hz and between 2000 and 2020 Hz just like every band of the spectrum of the color white has equal brightness, all of which combine to produce white. This type of noise is used for the purpose of testing audio equipment and masking other sounds. The sound is also used to create percussion instruments during audio synthesis in which a lot of noise has to be produced.
Another area where the usage of white noise is quite well known is the assistance it provides in sleep. It serves to overcome the background noise, and this is of great help in helping people fall asleep. This is particularly effective when it comes to babies. Due to the fact that babies can hear sounds very easily, they find it difficult to sleep in a normal environment. White noise gives them a sense of familiarity and safety. It also serves to mask the noises that can cause a disturbance in your sleep. It’s also successfully used for tinnitus treatment. An example of the sound is the static that is heard on the radio frequencies that are not in use.
The brown or red noise refers to the sound that has low frequency, since its power decreases as the frequency increases. Therefore, brown noise has a darker, deeper sound than white or pink noise. It has a waterfall-like sound and it’s effective for masking low-frequency noise. It can however be applied to any system that witnesses an increase in power density with a decrease in frequency and vice versa.
Another name used for this type is Brownian noise. The signal produced bears resemblance to the Brownian motion, which is the movement of particles suspended in a liquid or gas, caused by the collision of molecules and particles. Since the particles move randomly, brown noise is sometimes also referred to as random-walk noise. It is used in climatology and sleep therapy.
Pink noise is the one whose spectrum falls off over time in a logarithmic fashion. As a result, the same power is found in the band between 20 and 40 Hz and between 2000 and 4000 Hz. Each octave comprises of the same amount of energy as the one above it as well as the one below it.
The usage of pink noise is based on the principle that it is the same as what humans hear. It’s making it highly useful for checking amplifiers and loudspeakers. Pink noise also sounds more pleasant to the ear than pure white noise and it can be used to mask disturbing sounds for sleep or concentration.
This type of noise has more power in the signal as the frequency increases. As blue noise has more power in higher frequencies, it’s often used for masking tinnitus sounds. Studies have revealed that retinal cells are arranged in the pattern of blue noise, which leads to good visual resolution.
Similar to blue noise is violet or purple noise. You might find this style is the opposite of brown noise as it witnesses an increase in power density per octave with increased frequency over a set frequency range. Just like blue noise, this type of sound can also be used in the treatment of tinnitus as it serves to mask the high frequencies heard by the patients of the condition. Unlike white noise, violet noise does not have a sharp sound, it rather sounds like a snake hissing.
Gray noise refers to the white noise that has been subjected to a psychoacoustic equal loudness curve over a certain range of frequencies. This gives the impression to listeners that the noise bears equal loudness at all frequencies, but it actually has more power at both ends of the frequency spectrum and less in the middle.
Other colors of noise
Less defined types of noises are present as well. This includes orange noise, which is a spectrum that has entirely eliminated a few bands centered on the frequencies of musical notes. They are referred to as sour notes which are used to test tuning.
Black noise is often called the output of a noise control system that brings about the cancellation of existing noise, thereby resulting in negative noise. Black noise is sometimes also referred to as the sound of silence.
Another type that you will find is green noise, which is the midpoint of the white noise. It is quite similar to pink noise but has a hump at around 500 Hz.
A direct relation is said to exist between colors, health, and sound. Thus, apart from the applications of the different types of colors that we have discussed here, there are certain things that you will find them to be useful for. Among the various colors that we discussed, it is the white noise which attains maximum attention from people due to the assistance that it provides in falling asleep. There is no denying that these colors are rather interesting to know about and provide you with many uses in the world of sounds.