Survey of Background Noise Level Inside Classroom on a College Campus
Abstract (300 words maximum)
Sound level measurements are made for twenty classrooms and learning spaces on the Marietta Campus of Kennesaw State University in Georgia, USA. Excessive background noise in learning spaces diminishes the speech intelligibility from the speaker to the listeners and vice versa. Initial measurements are taken using an iPhone and NIOSH (National Institute for Occupational Safety and Health) Sound Level Meter application, and the noise measured is in empty or nearly empty classrooms with no one talking. In addition, conformance with ANSI-ASA S12.60-2010/Part 1 (Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools) is evaluated. The Larson Davis Sound Level Meter, a Class 1 precision sound level instrument, is used to give a better understanding of the type of noise that is of highest significance. Nine of the twenty classrooms and learning spaces surveyed exceeded the maximum recommended background noise level of 35 dBA, with the most excessive violators located in the Mathematics and Textiles buildings with their HVAC systems operating.Next, a set of more controlled measurements are made, including accelerometer measurements on various parts of the target HVAC unit at each mode: high setting, low setting, and off. In addition to the sound level meters, the BK Connect system is used with both binaural headset microphone measurements and single microphone measurements to give a better understanding of the type of noise that is of highest significance. Following ASHRAE standards, it is shown that within the collected data, the most likely noise sources are due to turbulent air flow and fan noise. KSU is considering a trial modification of the duct-flow system in one classroom to reduce flow velocity and its associated noise level.
Academic department under which the project should be listed
SPCEET - Mechanical Engineering
Primary Investigator (PI) Name
Laura Ruhala
Survey of Background Noise Level Inside Classroom on a College Campus
Sound level measurements are made for twenty classrooms and learning spaces on the Marietta Campus of Kennesaw State University in Georgia, USA. Excessive background noise in learning spaces diminishes the speech intelligibility from the speaker to the listeners and vice versa. Initial measurements are taken using an iPhone and NIOSH (National Institute for Occupational Safety and Health) Sound Level Meter application, and the noise measured is in empty or nearly empty classrooms with no one talking. In addition, conformance with ANSI-ASA S12.60-2010/Part 1 (Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools) is evaluated. The Larson Davis Sound Level Meter, a Class 1 precision sound level instrument, is used to give a better understanding of the type of noise that is of highest significance. Nine of the twenty classrooms and learning spaces surveyed exceeded the maximum recommended background noise level of 35 dBA, with the most excessive violators located in the Mathematics and Textiles buildings with their HVAC systems operating.Next, a set of more controlled measurements are made, including accelerometer measurements on various parts of the target HVAC unit at each mode: high setting, low setting, and off. In addition to the sound level meters, the BK Connect system is used with both binaural headset microphone measurements and single microphone measurements to give a better understanding of the type of noise that is of highest significance. Following ASHRAE standards, it is shown that within the collected data, the most likely noise sources are due to turbulent air flow and fan noise. KSU is considering a trial modification of the duct-flow system in one classroom to reduce flow velocity and its associated noise level.