Could you please speak so that the people in the back can hear?
"後ろの席の人に聞こえるようにしゃべってくださいますか"
- Could you please speak so that the people in the back can hear?
- Please speak so that the people in the back of the room can hear you.
- Could you please speak so that everyone sitting in the back can hear you?
If it's ok to ask, could you please speak louder so the people in the back can hear you?
ご質問ありがとうございます。
このシチュエーションで、先生は小さい声であれば、「後ろの席の人に聞こえるようにしゃべってくださいますか」と言いたいなら、英語で「If it's ok to ask, could you please speak louder so the people in the back can hear you?」と言えます。
ご参考になれば幸いです。