A few more thoughts on how the audition process at orchestras is anything but impartial, and how some orchestras have no great will to increase African American membership.
First, many players auditioning are contacted in advance and invited to audition - either by friends or relatives already in that orchestra, or by an administrator. That means if an orchestra really is interested in increasing the number of African American players, they can increase the odds by inviting certain known players. How often has this happened? Not much, from what I hear.
Second, one of the best ways to get into any orchestra is to study with a current member of that orchestra. It does two things. The member can get his or her student work as a substitute in the orchestra - sometimes without a substitute audition - which means the student is getting valuable experience in learning the style of the orchestra, which will in turn make for a more successful audition. It also often means that the teacher, when he hears the student playing from behind the screen in an audition, can recognize who is playing. And so, if an orchestra really is interested in increasing its African American membership, it will begin a formal training program to nurture potential new members. That's happening at some orchestras.
By the way, the two items above are cost-prohibitive. It takes money to take audition after audition (airfare, hotel). It takes big money to study with a player in a major orchestra. This is another way some aspiring African American musicians find themselves at a disadvantage. Do any orchestras offer financial assistance? I'd bet the flutist from Chicago and the clarinetist trying out in New York had their expenses paid.