If you're not hearing the audio for chases or item pickups, and these options are selected 'on' in the app's settings menu, there may be a problem with your Text-to-Speech engine on your device.
Go to Settings > Language & Keyboard >Text-to-Speech output. You should then see a list of available TTS engines. We recommend choosing Google's TTS engine as this works best with Zombies, Run!
Go to your phone's settings menu, then go to General > Accessibility > VoiceOver > Speech and then select a Default Dialect. You'll need to make sure that you choose one of the available English Language Dialects in order for item pickup and chase notifications to play correctly.