Advices I would like to give to a child who talks loudly and doesn't let others participate are -
1. Raise your hands for speaking.
2. Speak politely
3. Speak softly.
4. Wait for your turn.
5. Making class rules that there will be one response per day by a child.
6. Encouraging other children to speak by asking easy questions.
7. Making class rules for speaking and those who voilate them will get some punishment.
8. Working in groups with easier problems so that everyone can participate.