Brown noise, also known as Brownian noise or red noise, is a type of random noise that has a frequency spectrum in which the power density decreases as the frequency increases. In other words, brown noise contains more energy at the lower frequencies and less energy at the higher frequencies, resulting in a deep, rumbling sound. Brown noise is often described as a natural, soothing sound that is similar to the low roar of a waterfall or the sound of distant thunder. Some people find it helpful for relaxation, meditation, and sleep, as it can mask other sounds and create a sense of calm. Like other types of random noise, brown noise can be generated using various techniques, such as using specialized software or electronic circuits. It is also used in various applications, such as in sound engineering, music production, and acoustic testing.