All singers and instrumentalists are musicians. Despite the fact that they are using their voice the singer must create and convey a musical idea. This idea might be a relatively simple pop song or a more complex one, like those typically found in jazz and opera. Interestingly, I can recall a conversation between Ella Fitzgerald and Andre Previn. Previn is one of the few musicians who can play jazz and classical music. At one point in their conversation Fitzgerald, being modest, stated that she wasnt really a musician. Previn wisely disagreed with Fitzgeralds assessment. Im with Previn.