Urban indoor noise level characterization in the Medium Wave band

Indoor and outdoor noise field strength levels in empty channels in Medium Wave have been statistically analysed in five office buildings sited downtown in Bilbao. In order to analyse the spatial variability, median values of each location´s field strength time evolution values have been averaged, floor by floor and averaging every floors at once too. An average noise field strength value of 69.3 dBμV/m is obtained at 675 kHz, 66.0 dBμV/m at 1035 kHz and 65.2 dBμV/m at 1242 kHz. The spatial standard deviation is close to 10 dB. Similar values are obtained for outdoor locations but, in both cases, noise field strength levels were high, if compared with values reported in ITU-R P.372 [9] for outdoor reception. In the other hand, in order to analyse the time variability, mean values and standard deviations with locations of time standard deviations have been calculated. Values are not high, so generally, spatial variability is much higher than time variability.