Sound is at its core, energy being transmitted from one place to another. It does this through waves of pressure. With the right magnitude and frequency, the energy in sound can actually knock things over or shatter glass. So clearly sound has power. If you add order to sound, you get specific noises. These noises can be arranged in patterns to create music, which could be argued to have a power of its own.
Words can be written on a page, but when we speak them aloud we add the power of sound to their meaning. (I find it ironic that our modern society only honors things that are "in writing.") Words are an idea, while speaking is an action. The Genesis account describes God creating the universe merely by speaking.
When used well, words can communicate ideas and cause people to grow. But words can also be damaging, both when they are true and in different ways when they are not. Words can be used to control people, or to set them free. Speaking words aloud usually magnifies their effect on the emotional level.
There is also a connection between worship and music here as well, but I don’t pretend to understand music in the slightest. Many people have a powerful reaction to music, especially in the context of worship, and seeing the notes and lyrics written on the page doesn’t have nearly the same effect. I am not usually particularly affected by music, so this phenomenon is something I witness more so than experience directly.
We see a similar effect in prayer, which at its core, is simply communication with God. But we can combine that with the power of sound, by speaking prayers aloud. Now I have always been a fan of saying my prayers silently, based on the idea that God can hear what I am thinking anyway. I usually don't feel a need to bring other people into that dialog. But by not verbalizing them, my silent prayers miss out on the potential power available by speaking them aloud. I have seen this power at work, but I don’t understand why it works that way.
I have only recently begun to accept the idea that talking about things aloud has the potential to bring those things about, beyond the obvious practical results. If I tell someone to do something, they hear me and do it. If the same general principle is applied to God, who can always hear us, we find people’s speech having an affect on things they would otherwise have no control over. I can see a variety of potential reasons why God would set things up this way, but I don't claim to understand the why, I am just starting by exploring the how.
It also makes you wonder how much power someone who is deaf is missing out on. That may be why deafness is one of the first types of healings that take place in many evangelizing situations. It is opening up someone to the power of God in a whole new way. And as a primarily visual learner, I have probably undervalued the power of sound as well up to this point. (Tell me about it;)