- - - - - - - - - - - -       - - - - - - - - - - - - - - - - - - - - - - - - -0.6---       t -  - - - - - - - - - - - - - -  -  - - - - - - - - - - - - t - - - - - - -  - - - -0.2              --------  - -------a                                         -       - - --- - - - -0        100    200    300    400    500     600    700    80


    400
Frequency (Hz)


  Figure 3 -14 The topmost plot shows r22 , the coherence between the inputs. The next two plots are ly and r2, the ordinary coherence functions between each input and the output. The bottommost plot is r2.,, the multiple coherence function.


    To distinguish the effect of x, from X2 on the output, the characteristics of the blower and pump are studied. For the blower and the pump, the blade passage frequencies of the