Aircraft noise exposure and children's cognition: Evidence for a daytime NAT criterion

There is growing evidence that chronic aircraft noise impairs children's cognition. In the literature, LAeq is the dominating noise exposure metric, although alternative metrics have been included in order to achieve a substantial increase in explained variance of children's cognitive performance (e.g. Kamrath & Vigeant, 2014). In the German legal foundation, LAeq daytime, LAeq nighttime, LAmax, and number above threshold (NAT) night time criterion exist as noise parameters for effects on children (FluLärmG 31.10.2007 2550). Unfortunately, LAmax and NAT lack empirical evidence and only refer to noise at night. Concerning effects of aircraft noise on reading performance, these night-related measures are not suitable for explaining potential underlying mechanisms such as impairment of classroom instructions (Clark et al., 2014; Spilski et al., 2016). Consequently, for daytime exposure, an examination of alternative metrics and possible effects is mandatory. We present a theoretically motivated secondary analysis of the NORAH data set (Klatte et al., 2016) in order to consider alternative noise metrics. In the NORAH study, children's cognition, potential moderating and mediating variables, and different noise exposure metrics on the individual and class levels were assessed in 1.090 second-graders living in the vicinity of Frankfurt/Main airport, Germany. Aircraft noise exposure was calculated on the basis of radar data from the Flight Track and Monitoring System (FANOMOS), provided by German Air Traffic Services. We calculated multilevel analyses with robust estimation algorithms (MLR) and indirect effects (mediation models) with different noise metrics (LAmax, LAeq, NAT). We found empirical evidence for a mediating role of classroom instruction in the relationship between aircraft noise and reading performance; however, only by the modelling with LAeq08-14 and alternatively with daytime NAT60. These results show that the NAT60 criterion is better able than LAeq to explain children´s reading performance by the impairment of classroom instructions as the underlying mechanism.