Soundscape and indoor air quality in naturally ventilated educational environments: a multi-domain study

In this study, indoor air quality (IAQ) and acoustics were jointly analysed to determine their i) combined effect on students' performance in a math task, and ii) cross-modal effect on soundscape perception. 192 students (12 to 14 years) took part in a laboratory experiment. Students were separated into two classroom-like chambers with different IAQ conditions: a CO2 concentration of 800 and 2000 ppm, respectively. The participants were asked to solve calculations and answer a soundscape questionnaire in three listening conditions: quiet, a natural scenario with birdsongs, and one scenario with children's playground activity sounds. In the latter two conditions, the sounds were played back through headphones at a level of 47 dBA. Results show that students had faster response times in the math task in quiet compared to the listening condition with children's activity sounds, while maintaining a similar task accuracy. No effect of the IAQ conditions and natural sounds was found on the task performance. No cross-modal effect of CO2 concentration on soundscape perception was detected. Regarding soundscape assessments, playground activity was rated as the most annoying listening condition, while listening to birdsongs was the most pleasant one, despite its noise level exceeding the quiet condition.