Of the 15, i think only 6 (have to go back and check) had moderate to severe audiogram changes.Someone can check my math since I have not spent more than five minutes on this. 4 patients out of 15 treated with the drug got about 110% increase in word scores. Since the average increase for all 15 patients was 30% it means that the remaining 11 patients got no increase in word scores. The information they choose to publish is kind of selective. But they are not the first company to do it. So 27% got a material increase while 73% saw no change at all. If my math is right then the outcome is not normal distribution but rather a digital outcome that seems a bit odd.
People with mild losses generally have pretty normal word scores to start with.
I would also assume changes in the ultra high frequencies are more important for speech when you have bigger deficits up to 8000 Hz. I posted a study earlier in this thread about a subset of profoundly deaf people (based on standard audiogram) who had surprisingly good speech. It turned out that, though these people had profound loss up to 8000 Hz, they had normal hearing above 8000 Hz (rare for the profoundly deaf but it happens).
It seems likely that the limited speech and word information you get from the ultra high frequencies (probably has something to do with the "formants" of the lower frequencies is my guess, would probably have to ask an audiological researcher) becomes more important when you can't hear the lower frequencies well.
So really 4 out of 6 and there are lots of individual factors. But I can't think of any reason why for those 4 (but not for a single member of placebo) there would be a very significant increase in word scores if the drug didn't work.
The nice thing about this being IPO'd soon, though, is researchers who happen to be stock investors might start frequenting these threads and weighing in. As long as they aren't bears or bulls with an agenda, that will be really useful.