What is white noise?

White noise refers to the noise whose power spectral density is evenly distributed in the whole frequency domain. It can also be understood that it is uniform in the whole audible range (20 ~ 20000 Hz). The feeling of white noise to people is stable and flat, and it is a good signal frequency.

Ideal white noise has infinite bandwidth, so its energy is infinite, but this may not exist in reality. In fact, we often regard the flat signal with limited bandwidth as white noise. As long as the spectral width of a noise is far greater than the bandwidth of the system it acts on, and its spectral density is constant in this bandwidth, it can be regarded as white noise, such like electrical signal sound and rain sound commonly seen in life, the sound of sea waves, the rustle of the wind blowing through the leaves, the sound of running water, the sound of waterfalls and streams, etc

White light is a mixture of monochromatic light of various frequencies (colors), and white light has the function of mixing; The property of the spread power spectrum is called “white”, so the sound with this signal is also called white noise.

The magic “white noise” has amazing characteristics. It is like a white beam, composed of all colors, but what we see is white light.

In contrast, other noise signals that do not have this property are called colored noise. Colored noise is the sound emitted by irregular vibration. The power of frequency component is uneven and disorderly within the audible range. It is an abrupt sound and makes people unable to calm down. For example, the sound of cars on the road, the snoring nearby, the barking of dogs, the screaming of alarms, and the shouting of people.

White noise is a random signal power spectrum of the same unit. This is a good signal frequency and a theoretical construction. Like the light spectrum of white color, white noise fills the vibration frequency that can be heard by human ears, which can help a person relax or sleep.

White noise technology is also widely used in the field of architecture. In architectural acoustics, in order to reduce the noise that distracts people’s attention and does not want to appear in the internal space (such as people’s conversation), continuous low-intensity noise is used as the background sound.