We are very sorry about the unpleasant experience with loud beep sound while using Manga Rock. This issue is caused by a malicious ads that somehow activate this sort of "alarm" beeping sound.
For now, our team is actively investigating this issue and we hope to figure out exactly which ads is causing the issue to block it permanently. In the mean time, we suggest that you do a quick relaunch of your device and try to see if it reduces the frequency this happens.
Also, if you have any idea on how to solve this issue based on your experience, please let us know. We would really appreciate it!
Affected version: All iOS versions
First reported date: 5 Nov, 2017
Resolved date: TBA