The Nahuan or Aztecan languages are those languages of the Uto-Aztecan language family that have undergone a sound change, known as Whorf's law, that changed an original *t to before *a. Subsequently, some Nahuan languages have changed this to or back to, but it can still be seen that the language went through a stage. The best known Nahuan language is Nahuatl. Nahuatl is spoken by about 1.7 million Nahua peoples.