Bork Way Too Loud For Way Too Long

You make the loudest noise possible at your enemies. All creatures within a 20ft cube in front of you must roll a constitution save (dc as per spellcasting) or take 2d8 thunder damage. At the start of each turn you must roll a con save to keep concentration. After 4 rounds you are stunned for one round due to the physical stress of the spell.
(the damage levels up 1d8 for each spell level upcast)