Google ANDROID Quick Start Guide (4.4, KitKat) - Manual (Page 36)

ANDROID QUICK START GUIDE USE THE KEYBOARD 32
When you pause, what you spoke is transcribed by the speech-
recognition service and entered in the text field, underlined.
You can touch the Delete key to erase the underlined text. If you
start typing or entering more text by speaking, the underline
disappears.
To improve processing of your voice input, Google may record a
few seconds of ambient background noise in temporary memory
at any time. This recording remains on the device only fleetingly
and is not sent to Google.
To change your speech settings, go to Settings >
Personal > Language & input.
Settings