Not a heavy driver, but I think Reverse Flight has it, the 'shear' of 'core' engine exhaust / thrust against the relatively slow surrounding air causes the ear splitting scream, whilst a High ByPass ratio produces a gradual effect from the relatively slow to the High By Pass air, to the core exhaust / thrust air, lessening the 'sheer'
Is that roughly it?, I may not have articulated that as well as possible, I reckon I grasp it though.....
(Edited to change 'ration' to 'ration'....no high high Bypass rations at the Deli
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