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Another feature of the oboe is the point of
equalization. It is usually located just above the Gsharp
tone hole. The point of equalization is where
the wall thickness and bore diameter are equal. If
the bore is enlarged above the point of equaliza-
tion, the pitch level of the adjacent notes will
become sharper. If the bore size is decreased
above the point of equalization, the pitch level of
the adjacent notes will become flatter. Below the
point of equalization, the rules are reversed.
Enlarging the bore below the point of equalization
will make the adjacent notes play flatter.
Decreasing the bore below the point of
equalization will make the notes play sharper.
In order to select a tone hole design profile, the
pitch, timbre, and octave relationship must be
analyzed as well as the overtone partials. If we
have an oboe that is stuffy below the point of
equalization, we can increase the undercutting by
using an acute tool with a 40% penetration rate.
(Figure 5) This will free up the given note without
changing its pitch. If we have a note below the
point of equalization that is flat, we can use the
acute tool with more penetration. This will raise
the pitch of the lower octave without changing the
pitch of the upper octave.