Languages differ in the sounds they use. The Japanese language, for example, does not distinguish between ‘r’ and ‘l’ sounds as in ‘rock’ versus ‘lock.’ Remarkably, infants become attuned to the sounds of their native language before they learn to speak. One-year-old babies, for example, less readily distinguish between ‘rock’ and ‘lock’ when living in an environment where Japanese, rather than English, is spoken.