The Big Bang Theory's Simon Helberg to guest star

The Big Bang Theory's Simon Helberg will be joining Jim Parsons in the sound booth on Young Sheldon, reprising his role as Howard Wolowitz.

Helberg will lend his voice to the November 18 episode of Young Sheldon, An Introduction to Engineering and a Glob of Hair Gel, which will feature Sheldon's earliest interaction with the field of engineering. As an adult, Sheldon maintained a derisive attitude towards engineering, and in particular engineer Howard, on The Big Bang Theory.

The Big Bang Theory's Mayim Bialik reprised her role as Sheldon's wife, Amy Farrah Fowler, in a narration to the fourth season premiere. Meanwhile, Kaley Cuoco, who played Sheldon's friend Penny, had an uncredited cameo as the voice of a swimming pool in Sheldon's nightmare.