Part of macOS
DictationIMSpeech and dictation
○ Leave it
Turns speech into text, and text into speech.
What it is
Runs dictation and the system voices.
If you stop it
macOS starts it again straight away. Leave it.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
DictationIMcom.apple.speech.speechsynthesisdSystem SpeechSpeechDataInstallerdspeechmaintenanced
From Procession’s guide, in the words the app shows.