At about 11.6 seconds, this music cut is long enough to carry a full reaction without needing an immediate loop. Download the MP3 once to keep it available offline, then trim the opening or ending only if your app imposes a shorter notification limit. It can work as a ringtone or notification tone, though the vocal and backing music may compete with dialogue at high volume. Keep a Hello Darkness option nearby for sadder exits, and test playback through phone speakers before posting.