# Indoor Acoustic Requirements for Autism-Friendly Spaces
## 3 Results and Discussion
### Sound Field Distribution and Layout Optimization  
The first investigated case was the therapy room (small room, medical space), wherein, excluding the presence of sound absorbing furniture, carpets, or curtains, the sound absorbing units can be increased only by using ceiling elements or positioning sound absorbing panels on the upper part of the walls (Figure 14). Configurations (i) and (ii) have already been discussed in Section 3. If an entire ceiling is chosen as a sound absorbing surface (configuration iii), the reverberation time of the room decreases at 1000 Hz from 0.87 s (Figure 5) to 0.62 s  
Figure 8: Simulated RT for the soft room: spatial distribution at 1000 Hz for reverberation time (left-graduation range from purple = 0.36 s to red = 0.38 s) and definition (right-graduation range from purple = 0.98 to red = 1). (Figure 9, right) as a mean value; thus, the indoor sound field fulfills the optimal range for sensor devices, but it fails to comply with the best ASD individuals' requirements (0.4 s). Consequently, more sound absorbing surfaces are needed. Using frequency representations and considering for the sake of brevity 250 Hz representing low frequencies and 1000 Hz for mid-high ones (Figure 9), it is possible to highlight that corners present wave focusing in both cases. From the subjective point of view, no sensible difference with regard to JND was assessed in the blue and light blue areas. Conversely, when stepping inside green, yellow, and red ones, RT varied and one JND could be verified. In order to achieve better spatial performance using the same amount of sound absorbing surface, more distributed configurations are required. For this room, two variations of configuration (iv) have been proposed in order to verify if different configurations are to be chosen or if they provide similar results. Thus, in Appendix A, Figure A4 depicts the (iv,a) and (iv,b) sound absorbing area layouts and Figure A5 shows the results for configurations (iv,a) and (iv,b) for the reverberation time parameter at 250 Hz. Figure 10 presents the results at 1000 Hz. For the sake of brevity, only RT mapping is represented while C\({}_{50}\) and D50 are reported in tables. A more distributed application of sound absorbing material eliminates focusing effects in corners and improves the sensor range and individuals' perception. However, different spatial allocations can create visual discontinuities, which should comply with the individual requests of continuity and simplicity. For this reason, an acoustic neutral masking surface could be needed to hide the sound absorbing panels. Figure 10: Reverberation time for therapy room no. 4 for configurations: (iv,a) (left-graduation range from purple = 0.63 s to red = 0.68 s and (iv,b) (right-graduation range from purple = 0.63 s to red = 0.68 s). Spatial distribution at 1000 Hz. Figure 9: Reverberation time for therapy room no. 4, configuration (iii) for spatial distribution at 250 Hz (left-graduation range from purple = 0.87 s to red = 0.91 s) and at 1000 Hz (right-graduation range from purple = 0.62 s to red = 0.68 s). It is worthy to highlight that in these configurations, the reverberation time does not denote any significant variation in most available areas; thus, the two configurations provide the same effects. For this reason, in the following, only one configuration will be investigated as configuration (iv). Table 2 shows the comparison of the analyzed configurations for therapy room no. 4 in terms of C\({}_{50}\) and D\({}_{50}\) (average of the frequency range 250-2500 Hz, retrieved at 2 m from the source). As it is possible to notice, the values of these parameters increased when moving from configuration (ii) (Table 1) to (iii) and presented non-significant variations in configurations (iv,a) and (iv,b). The second case is represented by the bedroom (small room). The difficulties are related to the presence of large windows, doors, and furnishing accessories that could be sound reflecting (desks, wardrobes, shelves) and sound absorbing (bed, curtains).