For my voiceover/narration friends and singing students who follow me here:
A colleague asked a question about how to pronounce certain words when saying them comes out sounding wrong. In this case, it was "protests."
Here's my answer. It might be helpful to others of you as well.
"First, you need to do some practicing of those sounds together without the rest of the word. Step away from the mic for a bit. Go out into the sunshine and just do a bunch of sts sts sts sounds. So, it would be like saying the sts of "Protests" without the "prote." Practice that a lot. You are having trouble getting the tip of your tongue away from the "t" and onto the "s" and off the "s" quickly enough and you need to build some facility doing that. The sibilance and the length of sound will reduce once you gain speed with it without getting caught up on the word itself.
Whenever I have trouble with a particular word when I'm doing narration or voiceover work, I head right to tongue twisters to practice the sounds of the word.
A good one for sts is:
Amidst the mists and fiercest frosts,
With barest wrists and stoutest boasts,
He thrusts his fists against the post,
And still insists he sees the ghosts.
Do that one a lot and it will help.