Mariachi artists such as Pedro Fernández, Ana Gabriel, and American born mariachi singer Pepe Aguilar and more. The educational movement is controversial with some trained in the traditional manner, who are skeptical about these programs and their potential to change the tradition. The changes, especially standardization of publishing, are slowing impacting mariachi in Mexico. One difficulty of arranging mariachi pieces is that the son jaliscense is based on alternates between and time. Much of the published mariachi music is meant for people already familiar with the music to serve as guides, not to novices. On the other hand, many schools have
Mariachi problems recruiting mariachi instructors as many of these do not have required teaching credentials. For this reason, schools often hire trained musicians from outside the mariachi tradition. Many traditional mariachis are concerned that standardization will lead to fossilization and restrict improvisation. Other innovations in the United States have been the incorporation of styles of artists such as Elvis Presley, Freddy Fender and Glenn Miller, as well as the heavy-metal Mariachi band Metalachi. Another is the encouragement of female mariachis including all-female Mariachi groups such as Mariachi Mujer 2000 and Mariachi Divas de Cindy Shea. Mariachi Mujer has performed with Mexican