The chances are that your pet will not hear your voice, because just like in humans there is a sort of a “switch off” towards the outside world so do not expect it to hear the voice. Even if there are some signs of reaction towards the voice this could simply be a coincidence.
Also it matters if the seizures are short or long and at what frequency they happen. In some cases it could be that the seizures are only few seconds in which case it will probably hear you on the second repetition, but if the seizure is going on for some minutes or longer then likely it will be in its own dog or cat world.
Similarly, with the frequency, in some cases it could occur very frequently, numerous times per day and so you may think that your pet is not responding to you but actually it did not hear you.
I must say its a little bit of a freaky experience seeing dogs having petit mal seizures