Dead air that preceded and followed the speech samples was eliminated in order to alleviate demands on energy and attention while rating.
This region which will contain some circulatory flow will, in the text, be called the 'dead air region'.
This is because it occurs in the dead air pockets that accumulate in both horizontal and vertical corners (i.e. out of circulating air patterns).
A conical shock wave will be required to turn the main flow past this dead air region.
The strong shock wave grows from the spike tip as more air is fed into the dead air region.
There will be a re-attachment point where the pressure ratio across the oblique shock wave is just sufficient for equilibrium of the dead air region and no oscillation occurs.
This enlarges the dead air region forming a nearly normal shock wave at the spike tip (figure 9 b) which grows and replaces the conical shock wave.
Among professional broadcasters, dead air is considered one of the worst things that can occur.
