Audio in your Storyline and Studio courses could sound distorted on some iPads and iPhones. This happens when audio is encoded with any sample rate other than 44.1 kHz. Apple is aware of this issue but doesn’t have a fix for it yet. You can follow the bug’s status here.
Until Apple solves the issue, you can avoid it by encoding your media with a 44.1 kHz sample rate and reimporting it into your Storyline or Studio course. We recommend 16-bit 44.1 kHz mono audio. You’ll need to re-encode videos that have audio as well as audio tracks that were recorded in third-party apps.
For example, in the free Audacity audio editor, you can set the sample rate (44100 Hz) and sample format (16-bit) by going to the Edit menu, selecting Preferences, and clicking the Quality tab, as shown below. Other audio and video editors have similar quality settings.