The tone of the voice and the pitch are two of the most important factors while sitting in a process. They need to be adjusted as per GD or PI.
For suppose a good GD requires, a specific amount of voice modulation.
One needs to know where to lower the pitch and where to higher it and enter the discussion. If the moderator is looking for the GD to be cooperative and wants everyone to get a chance, remember to not cut anyone and keep your voice a little lower.
But, in case the moderator is vouching for your competence it is advisable to keep your voice a little higher.
For a PI, your tone should be confident enough to convince the interviewer that your words are credible. Remember to speak softly because you’re talking to someone one-on-one and someone who is also looking for a conversation to take place.