Jennifer Levey Sep 29, 2016:

When we compare Tony's comment "quite fiddly to get it just right" with Herbert's comment "on les supprime" we see which of them actually understands what's going on here. I guess one of them has never been to an outdoor event, stood at the front of the crowd, and wondered why they can understand nothing of what's happening on the stage, just in front of them, because of an 'echo' coming from badly set-up delay speakers - with a delay twice as long as that which would be experienced by folk at the back of the crowd if there were only front (un-delayed) speakers. In this context, there's no such thing as Herbert's "suppression" - only Tony's fiddly attempt to provide some (usually small) measure of compensation.

HERBET Abel Sep 29, 2016:

Si on ne corrige pas les différences de propagation, il y a des échos : on les supprime avec des lignes ou électroniques créant des retards

Tony M Sep 29, 2016:

For info... When I was head of the Sound Department for a leading theatrical supplier in the UK, one of my jobs as engineering consultant was to go round installing and above all setting up this kind of installation, using digital delay lines. Quite fascinating work, and quite fiddly to get it just right!