Hi guys,
I need help. I am currently setting up the EEG facilities using the ActiveTwo system. We encountered a very strange issue. When using eartips with foam for stimulus presentation, we observed a clear delay introduced by the sound card (approximately 100 ms). This was determined by comparing the timing of the original WAV file with the recording at the ERG 1 electrode. The ERG 1 recording is segmented by triggers sent from the stimulus computer to the acquisition computer to mark the onset of sound playback. The delay is calculated so that we can update the trigger timing and ensure that the EEG recording accurately reflects the true stimulus onset.
After switching to a loudspeaker, this misalignment still exists when comparing the actual sound file and the ERG 1 recording. However, in the ERP visualization, this delay seems to diminish even though I did not update the delay settings.
So, I am wondering that when switching the presentation mode (from in-ear to loudspeaker), is there any setting I need to modify?
best,
Jun