The 4 overblow is the next missing note, it’s a semi-tone above the 4 draw and a minor third above the 4 blow, sound familiar? Well that’s because it’s the same as the 1 overblow except it’s an octave higher. That’s an Eb on a C harp which is also the minor 3rd of the C major scale. The minor 3rd is a note used all the time in blues, so having this note means that you can now play convincing blues licks in 1st position. Try it out.
How to do it
As with the 1 overblow, the 4 overblow is done with the part of the tongue that makes the ‘K’ sound, as expected there is less air and volume here than the 1 overblow. Try putting your mouth in the shape of making the ‘oow’ sound but pronouncing ‘K’ with the tongue and pushing the air forward. Think about making a ‘Darth Vader’ breathing sound!