Keys in woodwind- the physical cut off frequency
When a tone is produced on a wind instrument, the bore of the instrument works as a resonator, to produce a pitch, but the internal surface of the bore is not a perfect smooth parallel surface. In woodwind, the keyholes even in a closed situation, still add (drill tone hole) or attach a little bit some space (plug/attach tone hole)in the bore. The rough and uneven surface of the bore causes energy loss, especially the high frequencies with short wavelengths. Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. The tone hole, the lattice rough surface, is the obstacle to the sound wave. When covering most and all tone holes of the woodwind instrument, short-wavelength in high frequency have trouble the get around corners and obstacles by traveling the whole length of the pipe, while the high frequencies (>1000Hz) are lost (Benada,1990). For fingering in woodwind instrument, it creates different patterns of open and close holes,The calcula