# Understanding the Pink Noise Curve: What It Should Look Like

May 17, 2024

Pink noise, often referred to as 1/f noise, is a signal with a frequency spectrum that has equal energy per octave or logarithmic frequency interval. It is commonly used in audio engineering, electronics, and even in the natural world to describe various phenomena. But what should a pink noise curve look like? In this article, we will discuss the characteristics of a pink noise curve and how it differs from other noise types such as white noise and brown noise.

Frequency Spectrum of Pink Noise

Unlike white noise, which has an equal distribution of power at all frequencies, pink noise exhibits a more specific distribution wherein the power spectral density is inversely proportional to the frequency. This means that lower frequencies have more energy compared to higher frequencies, leading to a descending slope when plotted on a logarithmic scale. This characteristic is why pink noise is also referred to as 1/f noise.

Visualizing the Pink Noise Curve

When graphed on a logarithmic scale, the pink noise curve will appear as a descending, straight line at a slope of -3 decibels per octave (dB/octave). This implies that along each successive octave, the energy will be evenly distributed, unlike in white noise, which exhibits a flat line with no change in power across different frequencies.

Comparing Pink Noise with White and Brown Noise

The three types of noise mentioned – pink, white, and brown noise – have unique curves when plotted on a graph.

White noise has a flat spectrum with no change in energy across all frequencies, leading to a horizontal line when graphed. This type of noise is often described as being hiss-like and is commonly used for masking sounds, audio testing, and sleep aids.

Brown noise, also known as Brownian noise or red noiseBrown noise, also known as Brownian noise or red noise, has its power decreasing at a rate of 6 dB per octave as the frequency increases. This noise type gets its name from its similarity to the random motion of particles observed by botanist Robert Brown, often referred to as Brownian motion. Brown noise has a strong low-frequency focus, making it rumble-like in character.

In summary, a pink noise curve should appear as a straight descending line on a logarithmic scale with a slope of -3 dB per octave. This unique characteristic differs from the flat line of white noise and the even steeper descent of brown noise, leading to different applications and properties.