Hi William,
Thanks for your answer. There are still a few things that are unclear to me.
1. If you say that it "works based on the volume of the phone", what do you mean with that? I assumed that the ad volume will be set to 50% of the current media volume, is that correct?
2. You also mention that there can be offending ads. This raises the question how the volume is regulated. I assumed that the AdMob SDK temporarily reduces the media volume with 50% before starting the ad, and restores it to the original media volume after the ad is dismissed. But if an ad can offend the volume rule, apparently the ad itself sets its output volume, which makes the setAppVolume function more like a suggestion... I tried it several times today, and none of the ads used a reduced volume (my media volume was at 90%, and all ads were really loud, definitely not 45%).
If it is true that the setAppVolume is nothing more than a suggestion for the ad, and if it is true that pretty much none of the ads follow that suggestion, then there is really no point in using this. In that case I will develop my own solution that temporarily lowers the media volume while presenting the user an ad.