Type to Siri Instead of Talk
Most of us are used to using Siri for a wide range of tasks. What you didn't know is that you can now type to Siri so that you can use the personal assistant even when you can't talk.
You need to turn this on in the settings, but once it is enabled you can type to Siri anytime, not just when you are making a correction to something that wasn't heard correctly.
Go to Settings -> General -> Accessibility -> Siri -> type to Siri -> On.