Sonic shriek is Vortex's power to emit/generate a highly enhanced scream of a high wind amplitude for a variety of purposes. It is a sub-power of Ghostly Wail but Vortex appears to limit the power to put into this attack. This reduces it's power and effectiveness but keeps him from being drained of energy like Danny.
During Torrent of Terror, Vortex used his own version of the Ghostly Wail during his first fight against Danny. Similar to Danny's and Dark Danny's in appearance and power, but on a lesser scale with a blue color and more wind-based. Vortex can generate a highly enhanced sonic blast of high wind amplitude for a variety of purposes, like causing mass destruction. But it is not powerful, as the damage Vortex cause to nearby objects wasn’t shown. Despite this Vortex is able to use it twice against Danny with no ill effects or because Vortex knows how much energy to put into the attack so it does not to run out of energy too quick, limiting the power put into this attack. This reduces it's power and effectiveness but keeps him from being drained of energy like Danny. Although its possibly not a true Ghostly Wail, it may be related to high winds.
This is probably how Danny was able to overcome his drawback to his own Ghostly Wail.
- 304. "Torrent of Terror"