Limón

Limón is the capital city and main hub of Limón province, as well as of the cantón (county) of Limón in Costa Rica. It has a populace of about 60,000 (including surrounding towns), and is home to a booming Afro-Caribbean community. Part of the community traces its roots to Jamaican laborers who worked on a late 19th railroad project that connected San José to Puerto Limón. 

Other parts of the population trace their roots to the Panamanian, Nicaraguan and Colombian turtle-hunters who ultimately settled along the Province of Limón's coast. Until 1948, the Costa Rican government did not recognize Afro-Caribbean people as citizens and controlled their movement outside Limón province. Accordingly of this “travel ban”, this Afro-Caribbean population became firmly established in the region, which affected the decision to not move even after it was lawfully allowed. The Afro-Caribbean community speaks Spanish and Limonese Creole, a creole of English.

White Noise

White noise is a kind of noise that is generated by combining sounds of all different frequencies jointly. In case you took all of the possible tones that a human can hear and combined them collectively, you would have white noise. 

The adjective “white” is used to illustrate this type of noise owing to the way white light works. White light is made up of all of the different colors (frequencies) of light combined together (a prism or a rainbow separates white light back into its component colors). Likewise, white noise is a blend of all the different frequencies of sound. You can believe of white noise as 20,000 tones all playing at the same time.

White noise

Plot of a Gaussian white noise signal.

In signal processing, white noise is a random signal with a flat (constant) power spectral density. In other words, a signal that contains equal power within any frequency band with a fixed width. The term is used, with this or similar meanings, in many scientific and technical disciplines, including physics, acoustic engineering, telecommunications, statistical forecasting, and many more. (Rigorously speaking, "white noise" refers to a statistical model for signals and signal sources, rather than to any specific signal.)

The term is also used for a discrete signal whose samples are regarded as a sequence of serially uncorrelated random variables with zero mean and finite variance. Depending on the context, one may also require that the samples be independent and have the same probability distribution. In particular, if each sample has a normal distribution with zero mean, the signal is said to be Gaussian white noise. In digital image processing, the pixels of a white noise image are often assumed to be independent random variables with uniform distribution over some interval.

Some "white noise" sound.

An infinite-bandwidth white noise signal is a purely theoretical construction. The bandwidth of white noise is limited in practice by the mechanism of noise generation, by the transmission medium and by finite observation capabilities. Thus, a random signal is considered "white noise" if it is observed to have a flat spectrum over the range of frequencies that is relevant to the context. For an audio signal, for example, the relevant range is the band of audible sound frequencies, between 20 to 20,000 Hz. Such a signal is heard as a hissing sound, resembling the /sh/ sound in "ash". In music and acoustics, the term white noise may be used for any signal that has a similar hissing sound.

White noise draws its name from white light, which is commonly (if incorrectly) assumed to have a flat power spectral density over the visible band.

The term is sometimes used in non technical contexts, in the metaphoric sense of "random talk without meaningful contents".