For blind and visually impaired people, the access to spatial information is crucial. Therefore, the development of non-visual interfaces to spatial representations, e.g. maps and floor plans, are important tasks. In earlier empirical work [19], we investigated virtual haptic floor plans, accessible through a Phantomforce feedback device, which allows haptic exploration of virtual objects (walls), in combination with sonification for representing overlapping objects (windows). In the following we present an empirical study on multiple-overlap constellations (in the room-plan scenario: walls, windows and radiators). We reduced the complexity of the environments from complete apartments to only one wall and overlapping subsections, to focus on the spatial accuracy of acquired knowledge. This one-wall experiment has two goals: to compare the accuracy of size and position estimation with the experiment with complete apartments and to investigate the usability of sonification to represent overlapping entities at walls. Qualitative measures on the correctness of overlap-relationship identification and quantitative investigation on the accuracy of size and position estimations are discussed. The results can be extended to the use of sonification to represent overlapping entities in general.