A December 14, 2017 application from Apple to the US patent Office shows Apple’s interest to patent, “a digital assistant that is capable of detecting a whispered speech input and providing a whispered speech response.”
Why would you want Siri to whisper to you?
One benefit could be to have a digital whisper bot in your pocket for ASMR sessions. Siri would not be the first virtual ASMR artist though, Amazon’s Alexa can already whisper (see link at bottom).
I don’t think ASMR sessions are Apple’s intent. Their proposed benefit is more about privacy and courtesy.
2020 update: another report of a virtual-touch haptic device that could someday enhance ASMR videos (Summary; Research Article).
Initial 2017 post: Video ASMR artists can directly stimulate ASMR in viewers with gentle sounds, soft voices, and comforting visuals.
But they have been unable to directly stimulate the sensation of touch through a video. And touch may be the strongest trigger of ASMR.
Could there be a way to feel the touch of someone who is in another room or even in another country?
Researchers at Simon Fraser University in Canada have designed gloves called Flex-N-Feel to be worn by individuals at separate locations. When one person Flexes their fingers in the gloves, the other person Feels the touch via vibrotactile sensations on their skin.