The university policy on credit hours may be found here: http://web.csulb.edu/divisions/aa/catalog/current/academic_regulations/credit_hour.html
More specific information regarding modes of instruction and course classification may be found here: http://web.csulb.edu/divisions/aa/catalog/curr_handbook/section_4/4-2_classifications.html
In accordance with national standards, each semester unit corresponds to approximately 45 hours of work per semester, counting both class meeting time and outside preparation and study. For a traditional lecture or discussion course, this means that the class will meet one hour a week for every unit in a fall or spring semester (15 weeks of class meetings). For a laboratory or activity course, the class may meet two or three hours per week for every unit.
Music ensembles fall under two main classifications: C-10 and C-11 courses are “activity” courses which meet for two or three hours per week for every unit. Major Performance Organizations are classified as C-21 and meet for up to five hours per week for every unit.