Schools in a number of American states, including Florida, New York and Washington, have had microphones and speakers installed in classrooms so staff can make themselves heard.
Some UK schools, such as Fulfen Primary in Staffordshire, are also trying "surround sound" systems.
Experts say such technology is necessary in the modern classroom, as teachers have to compete with more noise than ever before from a range of sources - including ventilation systems, traffic outside and pupils in overcrowded classes.
They also say many younger children experience hearing impairments due to ear infections, and teachers using microphones can improve these pupils' performance.
'Attention-grabbing'
At Fenton Charter School in Los Angeles, all 44 classrooms contain wireless microphone systems.
Teacher Lizette Adkisson said she was sure it helped her students grasp concepts more effectively.
"I don't have to strain my voice any more. I just speak in a normal tone and it grabs their attention. And I don't have to repeat myself as much."
Ms Adkisson often allows her students to use the microphone when reading or asking questions during class, a practice which she says encourages participation and gives children confidence.
One of her pupils, nine-year-old Reymond Maldonado, said: "When she gives directions, I don't have to walk up there and ask again.
"And I don't have to scoot up in my chair to try to hear her."
Research
Ken Ullrich, a clinical audiologist in Wenatchee, Washington, says at any given time, at least 30% of elementary pupils have some degree of hearing impairment caused by middle ear infections.
He says the use of microphones - including hand-held, lapel and collar microphones, and headsets - in the classroom is "long overdue".
"Classroom amplification will do for children's listening and learning what classroom lighting did for children's seeing," he said.
A government-funded study carried out in the US more than 20 years ago looked at the effects of louder teacher voices on the performance of pupils.
During the three-year study, the scores of students in younger grades increased in listening, language and word analysis when teachers used microphones.
The research also showed pupils in other grades improving in other subjects such as maths.
More recent studies are reported to have indicated pupil improvements in speech recognition, reading comprehension, and learning behaviour.
Acoustics
In a similar vein, research published last year in the UK suggested that poor acoustics in primary shool classrooms could prevent pupils from learning.
The study indicated that many rooms had problems with acoustics, meaning that pupils had to struggle to hear and teachers had to shout to make themselves heard.
The researchers from Heriot-Watt University in Edinburgh found that children sitting in parts of classrooms with particularly bad acoustics - "dead spots" - can miss out on whole lessons.
The study, which examined 70 primary schools in England, Scotland and Northern Ireland, also found a correlation between poor acoustics and higher rates of sickness among staff - with increases in sore throats and stress.