Tyson comes from a family of late bloomers, especially when it comes to male voices dropping.
For Jethro, his voice began breaking when he was fourteen and lasted for almost an entire year before it settled. John’s voice began breaking when he was sixteen and took five months, where Richard’s began at fifteen and took almost seven months.
Tyson’s voice didn’t begin breaking until he was fifteen and took roughly eight months to finish*; which meant that Jethro didn’t hear his baby brother’s ‘adult voice’ until he was nineteen and used his break in army training to visit his older brother.
James’ voice won’t begin breaking until he is sixteen (20th March 2022) and will take around seven months to properly settle.
* This means that in Teen!Verse and Hogwarts AU/Honey Badger SU Tyson’s voice is still breaking: teen!verse is beginning to break, and Hogwarts AU/Honey Badger SU is towards the end of his voice breaking.