The Echo options are at the bottom of the Speech tab of Settings.

Speak each letter as you type (Key Echo)
Readable says each letter as you type it. Off by default.
Speak each completed word as you type
Readable says each word when you finish it — when you type a space, Return or punctuation. Off by default.
Speak dictated phrase back when listening stops
Echo dictation: when you stop voice input, Readable reads back what it transcribed. On by default.

You can use letter and word echo together. Key Echo is paused while voice input is listening, so it can’t feed back into the microphone.