Pink noise is a sound somewhere in between white noise (think static from a TV) and brown noise. It contains a range of high-frequency and low-frequency sounds (as does white noise), but has a greater emphasis on lower frequency sounds. It is often described as being smoother and more relaxing than white noise. A real world comparison of pink noise would be medium to light rainfall or wind.
Like white noise and brown noise, pink noise if often used to promote better sleep. It can help mask unwanted and disturbing sounds like noisy neighbours or traffic. Research has shown that pink noise can improve sleep. There is also evidence to show that it can help improve memory, although this may just be a result of a having a proper nights sleep.
Pink noise helps improve sleep by raising that the brain perceives as ‘quiet’. The brain is easily able to ignore the pink noise sound, and if the pink noise is playing at a volume above disturbing sounds, it masks them. Even if it is not masking the sound completely, it is able to reduce the degree of disturbance to a level that will not wake you.
The LectroFan is able to produce 3 pink noise sounds (as well as white and brown noise). The LectroFan is particularly popular because the pink noise it produces is non-looping and random. Some noise machines simply play a repeating track, which is a problem. The brain is able to recognise repeating patterns, and the end/start of the track. These can be more distracting and infuriating than the noise it is trying to mask in the first place. The LectroFan is also able to produce a range of white noise, brown noise and fan sounds.