What I never understood

[TehMastermind]

Within the anime, why did Obito's voice suddenly change once his mask came off?

 

[Umari Senju]

Wasn't it the Black Zetsu who was altering his voice so it sounded like Madara's? I guess once he lost the mask it was pointless to continue the charade of being Madara.

 

[Meee]

Becuz he stopped imitating Madara.

 

[TehMastermind]

Becuz he stopped imitating Madara.

But how would one change their vocals at a snap of a finger

 

[Sol Ku]

Becuz he stopped imitating Madara.

Or better yet, go with this ^
I thought you were talking about why they switched voice actors for whatever reason.

 

[Sol Ku]

But how would one change their vocals at a snap of a finger

Ever listen to metal? Metalcore or progressive metal? Most of their lead singers can go from a deep growl to a pretty high singing voice.
Practicing vocal range can help.

 

[Sir Blades]

Because Obito is really good at impersonations.

 

[Flaming Amaterasu]

Or better yet, go with this ^
I thought you were talking about why they switched voice actors for whatever reason.

The logical answer is because like most masks tight to the face, it muffles your voice, and of course, he stopped being like madara. However, if Obito was imitating madara's literal voice, then that is true talent, unless BZ was helping him with that, but I didn't take notice of any similarities betwee Madara and Tobi's voice.