When presenting audio in an Experiment Builder task on Windows, you have two playback driver options: DirectX and ASIO. For any experiment requiring precise synchronization between audio events and eye-tracking data, ASIO is the optimal choice.
- ASIO (Audio Stream Input/Output)
ASIO is a protocol designed for low-latency, high-precision audio that allows Experiment Builder to communicate directly with the sound card.- How it Works: By bypassing the standard Windows audio system, Experiment Builder can schedule audio playback with high precision, ensuring sound plays at the exact time requested.
- Performance: ASIO provides millisecond-accurate playback and recording with latencies of less than 3 ms. This allows for easy and accurate alignment with gaze data.
- Compatibility: ASIO is not supported on all sound cards. A list of verified sound cards is available in the Experiment Builder Manual (Help Menu -> Installation -> Windows PC Installation -> ASIO Card Installation).
- How it Works: By bypassing the standard Windows audio system, Experiment Builder can schedule audio playback with high precision, ensuring sound plays at the exact time requested.
- DirectX Audio
DirectX audio is suitable for use cases where precise timing is not critical, such as playing feedback sounds or general verbal instructions.- How it Works: When a sound is triggered, the audio buffer is handed off to the Windows DirectX system, which then schedules playback. This indirect process introduces a significant delay.
- Performance: Latency can range from 7 to 200 ms with high variability, making it nearly impossible to align audio playback precisely with gaze data.
- Compatibility: DirectX is supported on all standard sound devices.
- How it Works: When a sound is triggered, the audio buffer is handed off to the Windows DirectX system, which then schedules playback. This indirect process introduces a significant delay.