Is change in voice a sign that someone is having a seizure? what could these symptoms be the sign of?

Yes could be: One type of focal seizure that does affect speech is the complex partial event, which is perhaps presaged by an aura of a foul smell or taste, followed by automatisms, such as speech arrest, or bizarre repetitive verbalizations, mouthing movements, limb posturing or twitching, with amnesia for the entire spell, and a period of postictal confusion.

Vocal change & sz: Sometimes a vocal noise is part of a seizure, like a yelp or a yell. A change in the voice is not normally a seizure. People with seizures normally cannot speak. When they can speak, it may make no sense. There are some videos of this to compare to- see frontal seizure on youtube for example.