Bernadette's unusually high voice in The Big Bang Theory has a fascinating origins story. After several years of only running with five main characters, CBS expanded the cast of The Big Bang Theory by promoting a couple of recurring guest stars as mainstays. The first one was Mayim Bialik's Amy Farrah Fowler, the female counterpart of Jim Parsons' Sheldon Cooper, and Melissa Rauch's Bernadette Rostenkowski. The latter started as Penny's The Cheesecake Factory co-worker who eventually started a relationship with Howard. Aside from being the woman who tamed the Pasadena gang's sleaziest member, Bernadette was also best known for her voice.
As with many other sitcoms, The Big Bang Theory tried to give each of its cast members distinct personalities and traits. For the first couple of seasons, Rajesh Kootrappalli had selective mutism while Penny was committed to being an actress. Sheldon had a wide variety of idiosyncrasies such as knocking three times and saying "Bazinga!" to signal that he was joking. While Bernadette was part of The Big Bang Theory's cast, she wasn't always at the center of its storytelling, but any fan would instantly recognize her voice. What makes this more impressive is that it wasn't Rauch's normal voice.
Four years since the nerd-centric sitcom, Rauch reveals the origins of Bernadette's high voice in The Big Bang Theory on Mayim Breakdown. As it turns out, the idea to do the character's signature trait came just before she auditioned for the role. Inspired by the way her mom spoke, Rauch says that she wanted to stand out, so she decided to set herself apart by reading her lines in a high-pitched voice. As a native of New Jersey, she had to find a way to lose her mom's accent while mimicking how she talked, which proved to be a bit trickier than she initially perceived.
Rauch's gamble to do something different paid off after she was brought in as a recurring guest star in The Big Bang Theory. Just nabbing the job, even if the temporary stint was already massive for her. Thankfully, CBS saw the potential of her playing the role long term, so they decided to bring her in as a series regular in The Big Bang Theory season 4. Since then, she became a fixture on the series, playing Bernadette for nine seasons until the hit comedy wrapped up its run in 2019.
Bernadette's voice was also significant to The Big Bang Theory beyond just being a running bit. It added a layer of emotionality to the show's storytelling, particularly with regard to her relationship with Howard. The truth is, Bernadette wasn't the only The Big Bang Theory character known for her voice. Mrs. Wolowitz's gruff manner of speaking was also her signature trait, and in later seasons, Bernadette would occasionally start to sound like her mother-in-law. This was specifically important on the heels of Mrs. Wolowitz abruptly passing away as it could have been comforting for Howard to hear her wife sounding similarly like her.