Text-to-speech audio (or TTS) is computer-generated audio that course authors can use in place of voice-over narration. You can generate TTS using Storyline 360 or a third-party app. It’s typically used during the development phase as placeholder audio. This allows course authors to move forward with course production without waiting for a voice actor to narrate a course. Using TTS audio also helps get stakeholder approval of audio without spending time recording the final narration. Some designers use TTS instead of a human voice actor for their final audio to save money and make future course updates easier.