Figure 39. Directivity index for: (a) 11inch line microphone, (b) cardioid
b. Figure 310 shows the basic components of this microphone. Inline tube
(A) has a 1/8inch slot milled its entire length and a group of ports which act as
a linear tapering acoustic resistance. Inline tubes are equally sensitive to
equal sound pressures, and will cause equal voltages to be generated at the output
of the dynamic transducer unit (C).