Using the same fingering one time with and one with out an overblowing hole makes the tool sound in various hights; during this contents you speak of lower and upper register. So you truly need seven tone holes and an overblowing hole. Learning how to play higher registers on woodwinds like a recorder is therefore rather simple, and it makes things easy for the instrument maker: The tone holes and their distances for the higher octave are accurately an analogous as for the lower octave. Now overblowing works on clarinets, too, but the effect is different: The clarinet overblows not to the eighth tone on thescale an octave which is exactly double the frequency but to the 12th tone. The Italian word for here's duodecime,and so we call the overblowing key the duodecime key. A beginner must learn this and get used to it. Furthermore this has implications on the construction of the device: First it needs more tone holes than octavating devices, as a result of if you are looking to play scales up, note 9, 10 and 11 need their very own tone hole. This means there must be more tone holes than we now have hands. Then the tone hole positions for the lower scale can be alternative from that of the upper scale,particularly their diameter. Since this is nearly not possible, the instrumentmaker must find a compromise. The device makers before 1700 haven't mastered this as a result of they didn't have thetheoretical and functional historical past.