The roof is very high above the fans at the north stand and fairly high above those at the souh stand.
Up turned roofs generally have less acoustic capture than downturned ones. For instance, the south tribune at Dortmund is slightly downturned giving greater reflection to spread noise and chants at that end to give greater unity, that is then projected out into the whole stadium. The old Kop at Anfield had a shed like roof and was probably more famed for its atmosphere than the larger Holt End for this reason. Spurs new South stand has been criticised by some for being too airy and not quite the acoustic mass that was intended.
However, there can be a difference between whole-stadium acoustics/atmosphere and that for traditional home end approach alone. The barrel roof could contain/reflect the whole stadium sound really well to bring down that threshhold for fan engagement. Wembley does that, but the format is hopeless in terms of unified chants at the ends compared to the old Wembley. It will be about the balance between a big occasion stadium and one that can be atmospheric on all occasions or can turn into a bearpit on any pivotal moment.