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 psychology studies can have start-up latencies in the hundreds of milliseconds. This can make presentation timing and synchronisation with other equipment a real issue.

For example, Psychology Software Tools (PST) the authors of E-Prime have conducted tests where start-up latencies were anywhere between a few milliseconds to over 350 milliseconds. 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.

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.