Siri robotic voice

Alright so what happened was I went to my phone and I said Hey Siri like i usually do and when I got a reply the voice was very robotic. I have an iPhone SE running iOS 11.2.6. After this had happened I continued talking to siri and got the same type of voice. I even restarted my phone. After the restart nothing had changed. I went into siri settings and changed the voice and that had fixed it, but my question is what was the voice that I heard and what could have caused it to happen.

BTW the voice kinda sounded like the bonzi buddy voice it was just really unlike the siri voice I ever heard even on the older firmwares.