German phrase
Sprechen Sie bitte lauter!
Meaning
Please speak louder!
When to use it
It asks you to speak up. It is a polite request when speech is hard to hear.
Example dialogue
Entschuldigen Sie. Sprechen Sie bitte lauter!
Excuse me. Please speak louder!
Oh, Entschuldigung, das Mikrofon war aus, ich schalte es jetzt an.
Oh, sorry, the microphone was off. I am turning it on now.