FAQ: How can I synchronize an audio file with a display screen
If the Display computer is a Windows PC there are two audio driver options in Experiment Builder (Devices Tab of the Structure Panel -> Audio -> "Audio Driver"): ASIO or DirectX. 

ASIO audio drivers provide precise and consistent timing and are much better than Windows DirectX drivers, which have both variable and longer latencies in comparison. This difference is an audio driver issue not related to Experiment Builder. If the project requires precise audio timing, please install an ASIO-compatible sound card and select ASIO as the audio driver in Experiment Builder.

If the Display PC is running macOS then there will be no option to change the audio driver as the drivers for Mac's hardware should deliver audio timing similar to ASIO.


For a list of up-to-date supported ASIO cards and installation instructions, please first make sure  you have updated Experiment Builder to the latest version. Then consult the "ASIO Card Installation" section in the Experiment Builder User Manual: Help menu -> Contents -> Installation -> Windows PC System Requirements. Click the Supported link in the table for the appropriate Windows OS (either 32 or 64 bit) to find the instructions for your particular sound card.

Please make sure to follow all of the installation steps (it is important you do not skip any steps). There are drivers that are specific to Experiment Builder that need to be installed which can only be accessed from the appropriate installation page for the sound card.

If  you are using a Windows Display PC with ASIO compatible sound card, or a display PC running macOS, you will be able  to synchronize audio with specific Display Screen nodes by  checking the Synchronize Audio property. This will reveal a further set of properties, including Sound File, which can contain a single WAV file or a link to a Data Source column that contains the audio files to be used for each trial. The volume, pan (balance), and offset can also be set. The offset can be a negative value, in which case the sound file will start playing before the screen is displayed.


If you have a Windows display PC but an ASIO card is not installed, then the Windows DirectX audio driver can be used for the project. When a project uses DirectX as the Audio Driver the Synchronize Audio property of Display Screen nodes will not be  available. To achieve optimal synchronization for DirectX, place a Play Sound action directly after the Display Screen action with the desired audio to be synchronized. Note that it is important to place the Play Sound action directly after the Display Screen action, not before it, to make sure that it is synchronized with the screen retrace as closely as possible.