White noise contains sounds of different frequencies (20 to 20,000Hz) which have similar power levels. Some sounds produced by nature can also have a very similar spectrum to white noise such as waterfalls, river or tree leaves rustling in the wind. White noise sounds can also be produced by man made items such as fans, vacuum cleaners, air conditioning, ventilation and more. White noise can be used to mask other annoying noise sources, which can help with sleeping and is also used for tinnitus treatment. Below shows the sound spectrum from one of the waterfall videos, longer videos for night long sleep can also be found here.