What is the suggested audio volume to design iPhone apps for?

Question

Is there a favored audio level that one should equalize their audio assets for playback on an iOS device? Twenty, 50% or 66% of max volume?

We're building a game that has a variety of sounds for alerts, sound effects and voice overs and we're trying to figure out a good baseline to tune it for.

I can't seem to find any documentation in Apple's Human Interface Guidelines for the iOS or Desktop regarding this - but that could be just my attempted search terms. If there isn't hard and fast number, what are people generally tuning for?

Thanks.

Answer 1

I think you should use 100% of the current volume state.

Here it goes, the iPhone Human Interface Guidelines for volume.