If you're pretty junior, or you work with a lot of loudmouths, you might need to turn the volume up higher to make sure you're listened to. If you're senior, or talking to a group of people more junior than you, you can get away with being a lot softer with your words. (And you often should, to avoid intimidating the juniors). And its not really about volume. Its about your word choice.

Low volume: "Hm, that sounds ok but I'm worried about performance."

High volume: "This will be unworkable because of performance problems. We need preliminary benchmarks, or a plan for solving those problems before we can move ahead."