At the Black Box ToolKit we specialize in helping you achieve millisecond accurate presentation, synchronization, and response timing in your computer-based psychology experiments. Here are just a few of the things that can stop you doing just that!

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Sound card start-up latency in psychology experiments

Soundcard start-up latency is the time it takes from telling the computer to play a sound to when the sound actually comes out of the speakers or headphones. Professional musicians have to deal with such issues regularly and a lag over a few milliseconds is considered unacceptable to the trained human ear. Empirical tests have shown that soundcards used in typical computer-based psychology experiment can have start-up latencies in the hundreds of milliseconds. This can make presentation timing and synchronicity with other equipment a real issue.

For example, Psychology Software Tools (PST) the authors of E-Prime have conducted tests where soundcard start-up latencies were anywhere between a few milliseconds to over 350 milliseconds (and in one case over three seconds!). This is in no way the fault of E-Prime but rather the hardware and operating systems used.

To compound the problem newer operating systems are actually worse than older ones. In the PST tests Windows XP did not have any soundcards with a start-up latency over 20 milliseconds. Windows Vista was averaged over 50 milliseconds and Windows 7 well into the 100's of milliseconds of lag. An excerpt from PST's results is shown below to illustrate the startling range of variation.

Adapter Type Machine Operating System Driver API/Expected Latency Mean (ms)     Std
Min (ms) Max (ms)
Sound Blaster SB0880 X-Fi     PCIe Ad Hoc Quad Core     Win 7x64 Manufacturer DirectSound 344.267 830.216 119.000 3345.000
Asus Xonar DG PCI Ad Hoc Quad Core     Win 7x64 Manufacturer DirectSound 69.643 1.277 68.000 72.000

Excerpt from PST's research on soundcard start-up latency

You are advised to view PST's full results and watch the video below explaining more about soundcard start-up latency.

Note how in the video a 7 year old soundcard out performs a newer model which is integrated into the motherboard!

A professional DJ shows you what start-up latency is with a practical demo of on-board sound versus
a dedicated soundcard.

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Founded in 2003 by a team of psychologists, software experts and electronic engineers we are dedicated to improving the millisecond timing accuracy and experimental rigor of researchers in the behavioral and brain sciences.

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