Everyone has brand spankin' new Audio Enhancment systems. Many teachers, including myself, don't see the need to use them. Teachers have taken a long time, years for many, to develop a quality teacher voice. Adding a microphone and few speakers isn't going to change the teacher's voice. These teachers haven't put on the microphones other than to have the levels tested.
I have to admit that I am one of those teachers. However, I am seeing the light and slowly walking toward it. My first experience with the system was to plug my iPod Shuffle into the "ext" port on the microphone. That allowed me to have music playing in the classroom so that everyone can hear it. I didn't think that it would make a difference in terms of teaching. Having the music playing, I could tell the students that if I can't hear the music, then the students are being to loud. It was the quietest afternoon of reading classes that I've had all year.
I have actually used the microphone as well. Here is where I feel that the microphone is key. I can sit at a table working with a small group of students working on a project. I can flip on the microphone and talk in a normal voice, not a big, deep, commanding teacher voice, and get the attention of the entire class. That includes little Johnny who is talking in the corner instead of doing the assigned reading. The microphone really does help with allowing the students to hear everything.
I think that I am slowly coming to the realization that Audio Enhancement is a valuable tool in the classroom. I don't think that I'll ever get over seeing a swarm of teachers in the hallway wearing microphone necklaces in the hallways.