CNN's Brandon Griggs wrote a column speculating as to why most computer generated voices, including Apple's Siri, are made to sound female.
Research suggests this preference starts as early as the womb, Nass said. He cites a study in which fetuses were found to react to the sound of their mother's voice but not to other female voices. The fetuses showed no distinct reaction to their father's voice, however.
Another answer lies in history. According to some sources, the use of female voices in navigation devices dates back to World War II, when women's voices were employed in airplane cockpits because they stood out among the male pilots. And telephone operators have traditionally been female, making people accustomed to getting assistance from a disembodied woman's voice."
Griggs suggests HAL -- and I'd add Vader, Cylons, CARR, WOPR, MCP, Agent Smith, and others -- have led North Americans to become more than a little leery of computers with boy parts. My take is that North American gadget users are a nerdy computer society, and we nerds prefer a sexy female voices telling us what to do. Economics 101.
Note: In the U.K Siri's voice is male. Read into that whatever you will.
Update: CNN also took issue with the synthetic sound of Siri's voice.
"What's interesting to me is how they seem to intentionally make her speech sound artificial -- they could choose to make her speech more seamless and human-like, but they choose instead to highlight the technology," she said. "That makes you aware of how high-tech your gadget is."
David Barnard of Tweet Speaker points out one of the more obvious explanations:
Not without dramatically increasing file size!