The intimate topography of the brain is laid out across a grid of 80 steel ceiling tiles as a spatialized form of tapping. The visitor can experience the dynamics of his cognitive self by fitting a wireless EEG interface on his head, that allows him to walk under the acoustic representation of his own brain waves.The accumulating resonances of impacted steel sheets generates penetrating overtones. The spatial distribution of impact and the overlapping of reverberations create a very physical soundspace to house an intangible stream of consciousness.‘Staalhemel’ (‘steel sky’, 2009) articulates the contradictory relationship we entertain with our own nervous system. Neurological feedback makes that the cognitive focus is repeatedly interrupted by the representation of this focus. Concentrated thinking attempts to portray itself in a space that is reshaped by thinking itself nearly every split second.