Wild Signals at Trigger Channel

We are using the Cedrus Stimtracker for EEG experiments in our lab, and it has been working super well with visual stimuli. When we visualise the acquired EEG data on EEGLAB, everything looks fine.

However, when we use it with auditory stimuli, we see fluctuation of signals / amplitude at the trigger channel when we visualise the data on EEGLAB.

Please refer to the screenshot. Event marker 1 marks the onset of audio, and the audio lasts for around 4 seconds. It seems that when a word is presented auditory, we will see a burst of signal at the trigger channel.

We sincerely hope for some advice. Thank you so much!

Which StimTracker model are you using? is it the original ST-100 model or the more recent Duo or Quad?

Thank you so much for your reply, Hisham.

We are using Quad.

I am not sure what the issue is. Please send me an email via the website so we can arrange for a zoom meeting. It would be faster for both of us!