The Raptor Alert app for Emergency Management requires permission to override your phones' alert settings so it has the ability to interrupt you and sound an audible alert. If you are not hearing the audible alerts, these documents from Raptor Technical Support will help you reset those settings and/or reinstall the app:

Apple iPhone:

Android:

Unfortunately, there is no support for other smartphone operating systems, such as Samsung's Tizen, but most of these will work with Android based apps.