"Señorita, hable más alto, por favor."
Translation:Miss, speak louder, please.
"Speak louder" is not really exactly correct since it is a comparison and we do not know to what. "Speak more loudly" is better.
When someone says speak louder it is saying speak louder than what you are currently. So that's the correct translation. 'More loud' is just not something which is said.
I answered "habla más alto" to a "write what you hear" form of this question. Duo said I incorrectly used the the command form "habla" instead of the 3rd person you form "hable". The conjugations I have of hablar show the formal 3rd person present of hablar as "habla," not "hable." Can anyone explain why Duo says it's hable here?
Habla is the present tense form for él, ella, usted. It is used to tell what happens or is happening. Señorita, (usted) habla español muy bien. Miss, you speak Spanish very well.
Hable is the imperative for usted. It is used to give a formal command. Señorita, hable (usted) más alto, por favor. Miss, speak louder, please.
Habla is also the imperative for tú. It is used to give a familiar command. Carmen, habla (tú) más alto, por favor. Carmen, speak louder, please.
Marcy - I hope DL are paying you for all the teaching you do. Your responses are always helpful.