Voice will raise and go down depend on the topic which you discuss in turn shows the confident about the topic.

The voice always get the attention of opponent that depends on what pitch you are in. A graph plot should show the proper voice as a sinusoidal wave with ups and down that is the perfect way of communicating. It cannot be with higher pitch or lower pitch always.

Increase your voice based on the points which you like to stress and come back to normal which it is not required that's how the points will be registered with opponent.

Lot of things are connected with voice example SHOUTING 1. to get the attention of someone
2. to show angry
3. to show confidence
4. to show commanding etc......

we can discuss more like this