d'Armond Speers spoke only Klingon to his son for the first three years of his child's life, the Minnesota Daily reports.
Speers says that he spent the first few years of his son's life speaking to him in the invented language of the alien race featured in the series "Star Trek" in order to better understand how children learn languages. Meanwhile, Speers' wife continued to address the child in English.
Speers told the Minnesota Daily,
I was interested in the question of whether my son, going through his first language acquisition process, would acquire it like any human language. [...] He was definitely starting to learn it.
Speers reports he "still gets nostalgic when he recalls singing the Klingon lullaby 'May the Empire Endure'" with his son.
Listen to Speers' son singing the Klingon Imperial Anthem here.
Wired reported on Speers' language experiment in a 1999 article in which Speers described the challenge of speaking to his infant son given that the Klingon language lacked words such as "diaper" and "bottle."
The article notes,
So Speers found himself using "thing which is flat" for table. "Alec very rarely spoke back to me in Klingon, although when he did, his pronunciation was excellent and he never confused English words with Klingon words," Speers says.
Eventually, Speers stopped using Klingon to communicate with his son, saying that his son "stopped listening to me when I spoke in Klingon" and "it was clear that he didn't enjoy it, and I didn't want to make it into a problem."
His son, now in high school, does not speak any Klingon, according to the Minnesota Daily.
Despite his interest in Klingon, Speers says he is not a Star Trek "fanatic."
I don't go to 'Star Trek' conventions, I don't wear the fake forehead. [...] I'm a linguist.