While writing this piece, trademarking intonation speech patterns is something that hasn't been done. However, if you think about it, it's not that different from trademarking a sound logo.
With voice technology, it becomes curial to expand and create brand associations through speech, voice, and sound. The recognizable voice-over of a brand that's been used consistently isn't just identifiable or associative because it's the same voice. The consistency in intonation and intensity patterns contributes equally as if not even more to brand association. When saying hello, goodbye, or any other recurring dialogue design, it's an opportunity to capture the brand's personality. When you think about it, I bet some people in your environment have a distinctive way of saying hello, goodbye, or telling a story.
For example, my grandma always says hello and goodbye with a distinctive intonation pattern and use of her voice that is not at normal to the Dutch language or the region where she lives. However, this makes her who she is. It belongs to her identity and personality. So, anyone who comes close to repeating this way of saying hello or goodbye, I immediately think about my grandma. It creates a sense of familiarness, preference, and trust.
Brands can develop speech pattern associations as well and bring the brand identity, and it's personality to life.