True, with power comes confidence which reflects in our voice too. 

 It is quite natural that depending on our position, our mental attitude will change and our body language will automatically adjust to match the dignity of that position, and the power of expression will reflect in our voice also.

Power plays a major role in everything. Usually attitude and speech will change depending upon the position they are handling. But basically it depends on the way they carry themselves.It may be a authoritative position (or) a normal position, its up to the people who are in that position.

When people have power they can express their views and followers are ready to adapt it. A powerful voice is always make the changes in the society. How the power is used depends upon the results will come.  When people listen the voice the man gets its confidence more and his way of approach in good things will yield more people as his followers. Modi voice is powerful now-a-days.

It is now with power comes a commanding voice. With power a person having meek voice also gains confidence and that show in his/her speech.

Indeed, power does impacts the way people respond to situations and how much confidence they have.

At times, it can make people feel superior and even arrogant at times.

Yes, power does corrupt everyone.  However, those who use power well, will always use it for constructive purposes.  Mahatma Gandhiji used it for constructive purposes.  Kamaraj, the great leader used power to do the maximum for the people of Tamil Nadu.  He always used power for constructive purposes.

Power was used by such people to really communicate to people and involve them in nation building.  Today, we do not have such leaders and the sad story of people being misguided continues.