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The different types of noise in our lives come from sources of all different kinds.

As an integral part of the world we live in, it’s important to learn about what different types of noise there are to fully understand them and how they affect us.

Where certain types of sound can heal, certain types of noise can harm.

So it’s important to understand the distinct differences between them.

In this article, we’re going to explore the various types of noise, how they impact us negatively or positively, and get a greater understanding of how noise has colour as well as form.

What is Noise?

Understanding the distinction between noise and sound is crucial.

Noise is a specific category of sound characterised by unwanted, disruptive, or undesired sounds that interfere with our ability to hear or communicate effectively.

It’s typically characterised by irregular or chaotic vibrations in the air or other medium, causing a sense of disturbance or discomfort.

Noise can come in various forms, including but not limited to loud sounds, random frequencies, background chatter, mechanical hums, or any other audible disturbance that hinders the perception or enjoyment of desired sounds or signals.

The perception of noise is subjective and can vary from person to person based on individual sensitivity, perceived levels and context.

Types of Noise

Here’s a summary of the most common types of noise that may negatively impact us:

Low Frequency Noise

Low-frequency noise is an integral component of our everyday environment.

Whether it emanates from the distant murmur of a nearby factory or the low rumbles of a large diesel generator, in the modern world we find ourselves constantly exposed to low-frequency noise.

This particular type of noise is particularly challenging when it comes to blocking or reducing at source, resulting in its propensity to spread vast distances in all directions.

Impulsive Noise

The construction and demolition industry is often associated with impulsive noise.

This noise is characterised by sudden and startling bursts of sound.

These high-intensity disruptions can be caused by various sources, such nearby construction sites, heavy machinery or explosives, or even a neighbouring property undergoing an extension or remodeling work.

The fast and unexpected nature of impulsive noise can be jarring and potentially hazardous, impacting our auditory system and causing a range of health effects.

Intermittent Noise

Intermittent noise refers to sound levels that exhibit rapid fluctuations, alternating between periods of increases and decreases.

This type of noise can arise from a range of sources.

Typical examples being a passing train, a car whizzing by, a machine at a local factory operating in cycles, or a plane flying overhead.

Continuous Noise

As the name suggests, this is a type of noise that’s constant, such as factory equipment, a motor or generator, an HVAC system or compressor.

A few minutes of measurement using a sound level meter is generally adequate to obtain a solid assessment of the noise level in continuous scenarios.

However, for a more in-depth noise analysis, utilising a calibtrated sound level meter with octave band analysis becomes essential.

Octave bands enable you to segment the noise into individual frequencies, providing precise information about the specific frequencies contributing to the overall noise produced.

To delve even deeper into frequency content, investigating the noise using 1:3 octave bands offers greater detail.

What is Noise Colour?

In various fields like audio engineering, electronics, and physics, the term “colour of noise” is used to describe different types of noise signals.

It’s like having different flavours or styles of noise.

Just as colours can look different to the human eye, different colours of noise can sound different to the human ear, and even have a different appearance as visual patterns.

Each colour of noise has its own specific characteristics and qualities.

Although humans cannot directly perceive the “colour” of noise, we can hear a combination of sound waves that consist of different frequencies.

Frequencies refer to the vibrations of waveforms that occur within a specific time frame.

It’s important to note that this concept differs from synesthesia, where individuals may perceive specific colours associated with certain sounds or frequencies.

Noise, on the other hand, consists of an infinite range of single-source frequencies.

One interesting aspect of noise is that it’s impossible to precisely measure the amplitude of each frequency, even with modern advanced hardware.

To better understand the characteristics of different noise types, we can categorise them into various frequency bands, such as:

• 0 to 1 kHz
• 1 to 5 kHz
• 5 to 10 kHz
• 10 to 15 kHz
• 15 to 20 kHz

By using a spectral analyzer, we can measure the intensity of each frequency band.

This information, along with watt measurements, allows us to determine the power of noise within each band, and subsequently assign names to different “colours” of noise.

Where Do Noise Colours Originate?

The idea of naming different kinds of noise using colours originated with “white noise.”

White noise is a signal that has an equal amount of power across all frequencies.

The name “white” was chosen because it was thought to resemble white light, which was at the time, inaccurately believed to have a similar flat power spectrum across the visible range.

After the term “white noise” was established, other colour names like pink, red, and blue were applied to describe noise with different spectral profiles.

Sometimes these names were chosen based on the colour of light that had similar spectra, although not in every instance.

Some of these colour names have specific definitions in certain fields, while others are more informal and not as well-defined.

In many cases, these definitions assume that the noise signal contains components at all frequencies, and the power spectral density per unit of bandwidth follows a power-law relationship of the form 1/f β.

This means that the noise is characterised by a certain exponent β.

For example, white noise has a flat spectral density (β = 0), pink or flicker noise has β = 1, and Brownian noise has β = 2.

It’s important to note that these colour names are used in different contexts and disciplines, and their precise definitions may vary.

What is White Noise?

White noise refers to a type of noise signal that contains equal power across all frequencies within a given range.

It’s often described as having a flat power spectrum, meaning that every frequency within the range is represented with equal intensity.

White noise is characterised by its random and continuous nature, resembling the sound of static or the hiss of a television or AM/FM radio tuned to a non-existent station.

白噪声包含一系列frequencies, including both audible and inaudible.

It’s commonly used in various applications, such as audio engineering, sound masking, and scientific research.

Its equal distribution of energy across frequencies makes it useful for testing and calibrating audio equipment, providing a reference signal, or creating a background sound that can help mask other noises.

Due to its consistent and uniform properties, white noise can help promote concentration, relaxation, and sleep by masking distracting sounds and creating a soothing ambiance.

It’s also frequently used in sound therapy, where it can help individuals with tinnitus or other auditory disorders.

What is Pink Noise?

Pink noise is a type of noise signal that has equal energy per octave across the frequency spectrum.

Unlike white noise, which has equal energy per frequency, pink noise exhibits a characteristic decrease in power as the frequency increases.

This means that as the frequency doubles, the power decreases by half.

Pink noise is often referred to as “1/f noise” or “flicker noise” due to its spectral profile.

It gets its name from the resemblance to the colour pink, which has a similar distribution of energy across the visible spectrum.

In terms of perception, pink noise is often described as having a balanced and soothing quality.

It’s considered less harsh and more natural-sounding than white noise.

许多人觉得放松和使用粉红噪声it for various purposes such as improving sleep, enhancing focus, or creating a calming background sound.

Pink noise occurs naturally in various phenomena, including ocean waves, wind, and heartbeat rhythms.

It’s also utilised in audio engineering, scientific research, and sound therapy applications.

In audio engineering, pink noise is used for equipment testing, room equalisation, and speaker calibration.

In sound therapy, it can help mask tinnitus, aid relaxation, and promote a sense of tranquility.

What is Brownian Noise?

Brownian noise, also known as random walk noise or random telegraph signal (RTS) noise, is a type of noise that exhibits a specific pattern of variation over time.

It’s named after theBrownian motion, which describes the random movement of particles suspended in a fluid.

Brownian noise is characterised by its random fluctuations that resemble a rapid and irregular switching between two distinct levels.

These fluctuations occur due to the random movement and collisions of electrons or other charge carriers within a material or electronic component.

The behavior of Brownian noise can be observed as a series of abrupt transitions or “jumps” between different voltage levels.

It’s often associated with electronic devices, such as resistors, where the thermal agitation of electrons creates the random voltage fluctuations.

In terms of its spectral profile, Brownian noise follows a 1/f^2 power-law relationship, which means that the power decreases as the frequency increases.

This characteristic gives Brownian noise a unique frequency distribution, with more energy concentrated in the lower frequency range.

Brownian noise has applications in various fields, including electronics, physics, and telecommunications.

这是在一些电子电路用于随机number generation, as well as in certain measurement techniques and scientific research.

What is Blue Noise?

Blue noise, also known as azure noise or gradient noise, is a type of noise signal that exhibits a specific spectral characteristic.

It’s named “blue” because it’s analogous to the colour blue, which is associated with higher frequencies in the visible light spectrum.

Unlike white noise, which has equal energy across the entire frequency range, blue noise has a power distribution that increases as the frequency increases.

It’s characterised by a higher concentration of energy in the higher frequencies, with the energy decreasing as the frequency decreases.

Blue noise is often described as having a “hissing” or “crackling” quality, similar to the sound of rainfall or rushing water.

It’s considered to be more “balanced” than white noise, as it lacks the low-frequency emphasis found in pink noise.

Blue noise finds applications in various domains, including digital image processing, computer graphics, and audio engineering.

In image processing, blue noise is used for dithering, which is a technique to reduce the visibility of artifacts when converting images to lower bit depths or displaying them on certain devices.

In computer graphics, blue noise is used for anti-aliasing, texture synthesis, and distribution of elements like points or particles.

In audio engineering, it can be used for dithering during digital audio processing or as a reference signal in testing audio equipment.

The specific characteristics and uses of blue noise may vary depending on the context and application.

But in general, it represents a type of noise signal with increased energy in higher frequencies, providing a balanced and visually pleasing distribution of frequencies.

What is Violet Noise?

Violet noise, also known as purple noise or ultraviolet noise, is a type of noise signal that exhibits a distinct spectral characteristic.

It’s named “violet” due to its analogy to the colour violet, which corresponds to higher frequencies in the visible light spectrum.

Violet noise is characterised by an increasing power distribution as the frequency increases.

It’s often considered the opposite of pink noise, as pink noise has a decreasing power distribution with increasing frequency.

Violet noise is sometimes described as having a sharper or more pronounced emphasis on high-frequency components compared to white or pink noise.

The energy in violet noise is concentrated in the higher frequency range, making it sound more “hissy” or “sharp” compared to other types of noise.

It can be perceived as having a high-frequency hissing sound or a rapid series of high-pitched bursts.

In certain applications, violet noise is utilised for specific purposes.

For example, it’s employed in some forms of acoustic testing, where its emphasis on high frequencies can help reveal flaws or irregularities in audio equipment or systems.

它也可以用于一些音频合成技术ques or as a test signal in audio engineering.

It’s important to note that the terminology and usage of violet noise may vary across different fields and contexts.

In general, violet noise represents a noise signal with an increasing power distribution as frequency increases, emphasising higher frequencies and producing a distinct sound characteristic.

What is Grey Noise?

Grey noise, also known as neutral noise or balanced noise, is a type of noise signal that exhibits a balanced energy distribution across the entire frequency spectrum.

Unlike white noise, which has equal energy per frequency, grey noise aims to provide an equal loudness perception across different frequencies.

The goal of grey noise is to create a noise signal that sounds equally loud or balanced to human ears, regardless of the frequency content.

This is achieved by adjusting the power or amplitude of each frequency component to match the equal loudness contour of the human auditory system.

In other words, the amplitude of each frequency is adjusted to compensate for the variations in human hearing sensitivity at different frequencies.

Grey noise is often used in sound engineering, particularly in acoustic testing, psychoacoustic studies, and audio calibration.

It can be employed to analyze the frequency response of audio equipment, assess the masking properties of sounds, or conduct experiments related to auditory perception.

Compared to other types of noise, grey noise may sound more balanced and pleasant to the human ear.

It lacks the sharpness or emphasis on specific frequencies found in some other types of noise.

However, it’s important to note that the perception of noise can still vary from person to person, and individual hearing characteristics can influence the subjective experience of grey noise.

Noises That Harm

Excessive or prolonged exposure to certain types of noise can have detrimental effects on human health and well-being.

Here are some examples of noise types that are known to cause harm:

Workplace Noise

Noise generated at the workplace, such as factories, construction sites, and airports, can reach high levels and pose a risk to workers’ health.

Constant exposure to loud machinery, equipment, or tools without proper hearing protection can lead to noise-induced hearing loss and other auditory problems.

Traffic Noise

Noise produced by road traffic, including cars, lorries, motorcycles, and public transportation, can be a significant source of environmental noise pollution.

Living near busy roads or motorways exposes individuals to constant traffic noise, which can cause sleep disturbances, increased stress levels, and even cardiovascular issues in the long term.

Aircraft Noise

Airports and areas near flight paths experience significant aircraft noise due to takeoffs, landings, and aircraft engine noise.

The high noise levels generated by aircraft can have negative effects on communities, including sleep disruption, annoyance, impaired cognitive performance, and potential health impacts related to chronic exposure.

Construction Noise

Construction sites are known for producing loud and disruptive noise.

Heavy machinery, pile drivers, jackhammers, and construction activities generate high levels of noise that can be harmful to nearby residents and workers.

Prolonged exposure to construction noise can lead to stress, sleep disturbances, and reduced quality of life.

Recreational Noise

Recreational activities such as concerts, sporting events, nightclubs, and personal listening devices can expose individuals to excessive noise levels.

These recreational noise sources can cause temporary or permanent hearing damage, especially when proper precautions, such as earplugs / ear defenders, aren’t taken.

It’s important to note that the harmful effects of noise can vary depending on the intensity, duration, and individual sensitivity.

How Can I Reduce Harmful Noise?

Whilst it’s almost impossible to stop the source of many of the external noises described above, there are ways to reduce its negative impact.

Firstly,contacting an acoustical consultantwhere required is an important step.

They can assess your home and see where improvements can be made to prevent noise ingress and reduce the negative impact noise is having on your life.

An acoustics expert can offer complete measurement and testing services, generate reports, and provide guidance on meeting the Building Regulations Approved Document E requirements for both airborne and impact sound concerns.

As part of their testing and analysis service, acoustic consultants can utilise advanced equipment such as the Norsonic Nor 848 acoustic camera.

This cutting-edge technology enables acoustic consultants to identify sound leaks originating from buildings, machinery, and the surrounding environment.

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Conclusion

In conclusion, many people are unaware that noise can have both shape and colour.

While most individuals are familiar with the physical characteristics and intensity of noise, they often overlook the fact that different types of noise exhibit unique spectral profiles.

Understanding types of noise and the concept of noise colour adds another dimension to our perception and analysis of sound, offering a deeper understanding of its diverse properties and impact on our daily lives.