Nice to see some empirical validation of valved N95 masks still being better than the vast majority of other "masks" when it comes to protecting other people. And of course valved N95 masks are the gold standard for cheap masks (not full organic vapor gas masks, etc) even outperforming non-valved N95 in protection of self because of the valve preventing them from becoming unsealed during peak outflow. And of course they are much more comfortable to wear for long periods and during heavy work.
I just wish the US government would go all in on production of real, effective, fit N95 masks and distribute them to everyone.
The authors themselves point out the valved N95 masks might be worse than what the raw results show:
"Furthermore, the performance of the valved N95 mask is likely affected by the exhalation valve, which opens for strong outwards airflow. While the valve does not compromise the protection of the wearer, it can decrease protection of persons surrounding the wearer." [emph. mine]
I'm pretty sure the difference they're referring to is already there in the raw results - remember, they're measuring how well the masks protect others against the wearer by filtering out expelled moisture droplets, and the results show that valved N95 masks are worse than non-valved (though about as good as the very best of the cotton masks).
I doubt the results completely account for the airflow effect, and perhaps the researchers were careful enough to note this.
After all, they merely tested one infected person speaking at whatever level is normal for that person at that stage of the disease. It's quite possible that the typical carrier has stronger flow. Besides, sometimes people yell - quite a few people have reason to be on edge these days.
Ouch. I read droplets and thought 'virus'. That said, my point about the speaker not being representative is still correct. We have no idea if the speaker's speech is typical. It could be their flow is lower than the average.
They tested with four speakers and ran additional tests with one speaker. Results are consistent across the speakers. Consider also that they are measuring the relative filtration of different masks, not the absolute filtration.
I just wish the US government would go all in on production of real, effective, fit N95 masks and distribute them to everyone.