Language attrition is the process of decay that a language experiences for lack of use. Attrition may take place at the level of individual speakers, who gradually forgets a language that they used to speak, or at the level of the speech community, which gradually shifts to another language and changes aspects of its original language in that process. Individual speakers whose competency in a language has been affected by attrition may be called semi-speakers, and languages with high rates of semi-speakers have been shown to undergo similar types of language change such as loss of grammatical and phonological complexity and irregularity.