In the average school day, children spend 75 percent of their time listening. They listen to their teacher, they listen to each other, they listen to presentations and videos and readings — they listen to learn. 

According to research, as many as 1/3 of all K-12 students are missing up to 33 percent of verbal communications in class. This is often attributed to poor acoustics and noise from heating, ventilation and air conditioning (HVAC) units. Research shows that excessive background noise or reverberation in classrooms interferes with communication and listening. A number of studies have reported that students comprehend and retain more knowledge in environments with proper acoustics.

HVAC and Hearing

HVAC equipment can play a key role in helping schools create quiet, comfortable classrooms for students and teachers. The Acoustical Society of America (ASA) developed an American National Standards Institute (ANSI) classroom acoustical standard to assist schools when designing classrooms with conditions conducive to learning.

According to the ANSI Standard for classroom acoustics, noise levels for unoccupied classrooms should not exceed 35 decibels. However, research has found that the average noise levels in many classrooms can be as high as 66 to 94 decibels. Consider that being in a room with a noise level of 72 decibels is comparable to standing next to a busy intersection. How much could you learn in a classroom with noise levels exceeding that?

Speech recognition capabilities are not fully formed in children, who are often ineffective listeners. This makes it difficult for them to separate speech from background noise or be able to correctly distinguish what is being said. Good acoustics help children recognize words and learn new information.

Designing Quiet Classrooms

Being aware of the specific acoustic requirements for schools — and understanding how they are different than those used for other buildings — is the first key step in planning for and addressing classroom noise levels during the design phase.  If acoustics is considered as a design parameter, meeting acoustic goals often results in a small impact on cost of a design, but if it is not considered until after the design is complete, costs can be prohibitive.

While it is best to place equipment as far from the classroom as possible, many schools are constrained by space and where the equipment can be placed while still meeting acoustic standards. In these instances, placing the equipment in a closet or enclosed mechanical room can help to decrease the noise level in the classroom.

When tucking the technology away isn’t an option, then selecting quieter equipment that is AHRI rated and labeled to meet acoustic standards is the next step. The industry has made significant progress in lowering the sound levels of air-cooled chillers, such as the Stealth® Helical Rotary Chiller, which uses multiple InvisiSound® acoustical treatment options to produce the lowest published sound

levels in the industry. When making a selection, it’s important to ensure the acoustic rating is for the whole unit, rather than for just one part of the unit such as the fan or compressor.

Because children have different acoustical needs, engineers and architects cannot rely on practices considered acceptable acoustically for adults when designing school spaces for teaching children.

Designing the classroom with acoustics in mind will lead to the best learning environment possible. Resources, such as those provided by the Acoustical Society of America, can help ensure you create a classroom environment conducive to the best learning outcomes.

Visit trane.com/acoustics for additional information.