Comment: This exercise is designed to combine the registers. The octave ee vowel has a falsetto like sound, however, there is chest voice involvement because of how smoothly the voice descends back to the tonic. In the louder ah exercise the chest voice is trying to combine with the falsetto on the top note, hence the scratchy sound.
Quote: ...closing the gap between the registers in the male voice must be done with extra care. It is not enough just to bridge the gap. Unless the "break" is smoothed over properly permanent imbalances will result. An important preliminary exercise for introducing a factor common to both registers is the octave jump. What this does is to help establish a resonance adjustment which is the same for each of the two registers. At the same time it prepares the way for a realignment of the registers in the area of difficulty by appropriate use of intensity. Once the resonance adjustment has been prepared numerous other possibilities soon open up. (The Free Voice)