Configured in Settings → Sound.

Sound As Alarm

When this preference is enabled, the sound is presented to Android as an alarm. This behavior makes Android playing the sound using the phone's speaker. Sometimes the sound is played both using the phone's built-in speaker and connected device (e.g., auto Bluetooth connection or headphones).

If this preference is disabled, the sound is presented to Android as media (such as music, videos, etc.) and outputted from the current default media device.

Reset System Volume On Service Start

This configuration allows setting device volume to a specified value whenever the service is started – for example, make it as loud as it can get. Resetting the system volume on start can prevent the alert not being heard due to the low system volume set in the past. Please note that the volume isn't returned to the original value when the service is stopped.

Vocie announcements sound

This section allows to configure the volume and the speech rate of voice announcements. On some devices an application restart might be needed for this preference to take effect.