I am not sure what you exactly means, but if it is screaming sound comming from MOTOR (happens also without prop at certain rpm), then I have information resulting from communication between us and AXI guis:
We have very specific use of those motors. Every outrunner has certain critical rpm which hits own resonantion frquency of the rotating bell. In case of AXI 2826/XX the rpm is somewhere at 9500rpm +/- something. We fly those motors at fixed rpm whole flights and for example old APC 12x6 prop works well at 9000 rpm what is very close to that critical rpm. If we fly at rpm where the bell wants to resonane, new motor will little ring whole flight. That sound is explorable during flight as a very silent difficult to hear clean ringing (clean means harmonic, no screaming etc). Long usage at this rpm, will kill both bearing and also the connection between bell and shaft. So early or later that ring will go to stronger and to mutlifrequency sound, resultig later to ugly scream at some rpm. Solution for this problem is new rotor and bearing. We fixed this way several motors, unfortunatly it must be done at AXI, because the shaft needs new washers of proper thickness with new or moved bearing, so it is not for amatheur work.
They told us that this is not problem of R/C flyers flying at wariable rpm. And BTW, this was reason why I use now new prop working at 11000 rpm :-)). An 3 blades is another thing which will save your bearing.