In the recent seasons, according to bulbapedia, it's the same voice actor, Ikue Ohtani so why did they change the pitch, they just wanted to try something new or something? or maybe it is a different voice actor??
I. . Don't hear any differences. But it's the same voice actor. It sounds exactly the same.
You must have never watched the original series, there is an obvious difference, in the original series the voice is more deeper and more male sounding, but in this season, Pikachu 's voice can get really high at times.