Would be interested to know a bit more about that "infamous A320 howl", and how the vortex generator overcomes it.
Thanks.
I’d assume that under certain flight conditions ( angle of the wing) airflow actively by on that vent will produce an unpleasant sound.
Not unlike you blowing over the top of a bottle.
That little ridge ( vortex generator) will deflect the airflow sufficiently to fix it.
But I’m not an Airbus guru.