1. Stop muttering and speak up!

2. Speak up! I can't hear you.

3. Could you speak up, please?

4. Would you speak up a little, please?

5. Speak up. Don't mumble!

6. Please speak up so that the people at the back of the room can hear you.

7. Could you speak up?

8. I'm quite deaf-you'll have to speak up.

9. Why don't you speak up? I'm your father!

10. You'll have to speak up, I can't hear you.

11. Don't be bashful — speak up for yourself.

12. Speak up?it's rather a bad line.

13. Could you speak up? We can't hear at the back.

14. She's no shrinking violet always ready to speak up for herself.

15. It's time to speak up for those who are suffering injustice.

16. You will have no one to speak up for you!

17. He is willing to speak up for the rights of women.

18. You'll have to learn to speak up for yourself.

19. Terrorism will spill over if you don't speak up. Malala Yousafzai 

20. Can you speak up? -- I can't hear you.

21. She was afraid to speak up in front of all these important people.

22. But then perhaps few have the nerve to speak up with their unit commander and two captains looking on.

23. She mumbled something and Dove asked her to speak up.

24. Some people not only fail to speak up but talk with their hands wandering to cover their mouths.

25. I felt like if I didn't speak up then(sentencedict.com/speak up.html), I would never do it.

26. If you're still unsure about what you are supposed to do, speak up!

27. Some students will be highly cooperative and attentive, and will speak up readily regarding the assignment.

28. While many in the Society seemed at ease with the practice, he had to speak up.

29. Often it does not occur to them that they can speak up, raise their voices in front of people.

30. If those with inside knowledge of the facts didn't speak up for Britain, who the hell would?