No, that's not it, we're measuring in incredulity units, which are syllables.

"One hun-dred and se-ven?!" == 6 syllables

"For-ty one?!" == 3 syllables

Also, the first one has more vowel sounds to really draw out to indicate higher levels of I-can't-even. It sounds only golly-jeepers in Celsius, and much more I'm-so-done-with-this-shit in Fahrenheit.