Combined and cross-modal effects of acoustic and indoor air quality conditions on sensory and cognitive responses of university students

• The combined and cross-modal effects of acoustics and IAQ on students were examined. • Combined effects of the stressors were found on response time in a calculation task. • The antagonistic combined effect might be explained through arousal theory. • Environmental stressors affected only the perception of the corresponding domain. • No cross-modal effects were found on soundscape and IAQ assessments. Indoor Environmental Quality (IEQ) plays a crucial role in occupant well-being, particularly in educational settings where suboptimal IEQ impacts students’ cognitive abilities and ultimately their quality of learning. Although research into IEQ in educational settings has increased recently, studies that concurrently examine indoor air quality (IAQ) and acoustic domains remain scarce. This study adopted a multi-domain approach by investigating the combined effects of these two domains on university students’ cognitive abilities, as well as their cross-modal impacts on soundscape and IAQ assessments. In laboratory conditions, 29 students were exposed to two ventilation regimes which led to two bio-effluent levels represented by two CO₂ concentrations (800 and 3000 ppm), and four auditory conditions representative of both mechanical and natural ventilation conditions (Quiet, Babble noise, Mechanical Ventilation noise, and Birdsongs) while performing a calculation task and completing assessments soundscape and IAQ perception. The results revealed a combined effect of IAQ and acoustics on calculation performance, with response times slowing down in quiet as bio-effluents increased. Moreover, only for a high bio-effluent level, response time was faster in Babble noise compared to Quiet or Birdsongs. We speculated that these effects could be explained by the arousal theory. No cross-modal effects of the two domains were found for assessments, while changes in one domain influenced the corresponding perceptual evaluation. Overall, cognitive performance seems to be mediated by an increase in sound-induced arousal, consistent with the Yerkes-Dodson law, with the arousal-performance curve further modulated by IAQ levels.