A closed side hole in an acoustical duct acts as a parallel resonator. When the duct is excited at a frequency whichs quarter wavelength corresponds to the side hole chimney length, the pressure waves are not propagated downstream the side hole.The closed side hole in a wind instrument air column thererfore constitutes a "notch-filter" for the radiated sound.A peculiarity of the bassoon compared to other wind instruments is the presence of finger holes with lengths corresponding to notch frequencies in the low mid frequency range around 2 kHz.Long-chimney, finger-actuated sideholes are possibly are a leftover from the keyless predecessors of the bassoon, where holes needed to be drilled obliquely to match acoustic and ergonomic constraints. The fact that they have not been replaced by short-chimney, key actuated side holes points to the perceptual importance of the long closed chimney effect.To demonstrate the importance of the closed chimney effect, we present artificial mouth measurements on a simplified bassoon (a pure cone with 3 side holes) where the chimney lengths were varied during playing.To estimate the importance of this effect on the nuances of timbre, artificial mouth experiments from german and french bassoon design are compared.