Thanks to Obi-Wandi, we learn that there was potentially an earlier edition of Gauntlet on the C64, which featured “easily comprehensible speech synthesis”. This was according to Happy Computer magazine and in their review of the Amstrad edition of the game.
Could any of those involved in the C64 conversion confirm this? Would be interesting though to learn if the reviewers got things correct.
Thanks to Ross Sillifant, it seems the best person to answer things will be a chap called Bill Allen. Is there an earlier edition waiting to be found?
Considering that the arcade hardware had a dedicated Music, SFX and Speech chip – having a C64 version that did it all would be potentially a bit of a pipe dream.
So far it seems Tony Porter from a Conversion Capers article in Retro Gamer Magazine issue 23 (Thanks Ross!) has confirmed that the speech sounded terrible and took up too much space, so it was dropped. We can still check with Bill Allen if there is still a version somewhere with the speech included.
Here is a gallery of articles mentioning the speech, thanks to Ross for sourcing!