When introduced a few years back, classroom sound-amplification systems filled a void that enabled teachers to be heard better. But they did not have rechargeable batteries or docking stations, which made it expensive and cumbersome. Frequencies were limited because the systems were based on FM-, VHF- and UHF-type microphones normally used in public-address systems. The microphones were heavy and not reliable for everyday use. They also lacked an equalizer, which enables a user to eliminate feedback or change the dynamics of a voice. But even with all the negatives, the systems provided a way for students to hear more clearly and comprehend better.

Now, improved technologies are providing teachers even more flexibility so a message can be heard with much less effort. The newer systems are ultra-light, easy-to-use, pendant-style wireless solutions that give a teacher control over the system from the pendant microphone. This feature enables a teacher to roam about a classroom and control volume from anywhere. The microphone can be worn comfortably around a teacher's neck, or used as a handheld for student use. Additional microphones can be added easily so that students and teachers can use the classroom sound-amplification system for presentation and discussions.

These new amplification systems come with charging docking stations that are easy to use. A comprehensive equalizer eliminates feedback. The microphones are equipped with NiMH rechargeable batteries that last 10 hours on a charge. The microphones are responsive, lightweight and use infrared technology.

Another new feature is designed for integration with other classroom audio sources. For example, a teacher can comment while a DVD is playing, and the DVD audio volume is lowered automatically. When the teacher finishes speaking, the volume automatically returns to the previous level.

Some states, prompted by research, are insisting that new schools built with state funds include sound amplification. With multiple audio sources, a powerful, wireless tool such as a classroom sound amplification system makes a lot of sense.

Why is sound amplification important? Young children require a more favorable acoustical environment than adults: Children cannot listen like adults because the auditory neurological network is not fully developed until about 15 years of age. Also, children do not bring 30-plus years of listening and life experience to a learning situation; hence, they cannot perform the automatic "auditory-cognitive closure" of missed information.

The results of independent research continue to reinforce the benefits of classroom audio for students and teachers. Put simply, the more students hear, the better they learn.

C. William Day is senior analyst at KBD Planning Group, Young Harris, Ga., a firm specialized in education facilities and technology planning. He can be reached at bday@kbdplanning.com.