Some travel a few blocks and others, hundreds of miles to attend weekly rehearsals every Saturday and Wednesday at Orchestra Hall in midtown Detroit. The youngest is 7 and the eldest, masters level in university. They give dozens of performances a year. These are the 750 classical and jazz musicians who participate in the Civic Youth Ensembles. Sponsored by the Detroit Symphony Orchestra, the CYE is the largest, most active program of its kind in the United States.