# Indoor Acoustic Requirements for Autism-Friendly Spaces
## 3 Results and Discussion
### Sound Field Distribution and Layout Optimization
Their position affects the layout of the sound absorbing elements and, consequently, the insertion of the microphone sensors. Diverse conditions can be analyzed as described above. In Figure A6 of Appendix A, configurations (i) and (ii) are described. From the simulation, it is possible to retrieve a mean reverberation time value for the empty room at about 1.3 s at the 1000 Hz frequency. As expected, the inclusion of furnishing accessories in the room (a desk, a wardrobe, and a bedroom with winter blanket and pillow) led to a lower reverberation time (RT = 0.7 s at 1000 Hz). Figure 11 shows the comparison in terms of the indoor distribution of the reverberation time at high frequency (in Appendix A, Figure A7 depicts the reverberation time at 250 Hz and Figure A8 the configurations outlines). In this case, the presence of a very large window and the absence of sound absorbing elements on the ceiling create an uneven acoustic field. The sound focusing in the corner remains rather marked at low frequency. The need to add sound absorbing units is mandatory for both the insertion of acoustic sensors and for autistic individuals' purposes. Accordingly, one JND variation was verified in both sound field distribution. Simulations demonstrate that a ceiling sound absorbing surface could be sufficient to improve reverberation time at low frequencies. As described, it can also be placed inside the room \begin{table}
\begin{tabular}{c c c c c c c}  & Configuration (Hi) & Configuration (Gy) & Configuration (Gy) \\ \hline Frequency & 250 Hz & 1000 Hz & 250 Hz & 1000 Hz & 250 Hz & 1000 Hz \\ \hline C\({}_{50}\) (dB) & 10 & 14.5 & 8 & 12 & 8.5 & 13 \\ \hline D\({}_{50}\) & 0.9 & 0.96 & 0.8 & 0.95 & 0.85 & 0.95 \\ \end{tabular}
\end{table} 
Table 2: Comparison of the analyzed setup for therapy room no. 4 in terms of C\({}_{50}\) and D\({}_{50}\) indexes. Figure 11: Reverberation time for bedroom for configurations: (i) empty room (left-graduation range from purple = 1.33 s to red = 1.37 s), (ii) room with furniture (right-graduation range from purple = 0.72 s to red = 0.76 s). Spatial distribution at 1000 Hz. in different ways. Appendix A, Figure 8, reports the modeled room for the following configurations: (iii) with sound absorbing surface distributed only on the ceiling and (iv) with the sound absorbing surface distributed partially on corners and partially on the ceiling. Figure 12 shows the comparison of the spatial distribution of the reverberation time parameter at 1000 Hz for the modeled configurations (in Appendix A, Figure A9, the acoustic field distribution at 250 Hz is reported). Table 3 shows the comparison of the analyzed setup for the bedroom in terms of C\({}_{50}\) and D\({}_{50}\) (average of the frequency range 250-2500 Hz, retrieved at 2 m from the source). In this room, it could be highlighted that values increased, changing from configuration (i) to (iii) and provided non-significant variations for configurations (iii) and (iv). Accordingly, no JND variations were found. The quality of indoor sound field distribution at the low and high frequency range improves if the sound absorbing material is located only on the ceiling. The sound focus in corners decreases significantly, but these positions do not represent the best locations for sound detection devices. These facts demonstrate how configurations (iii) and (iv) suit the requirements of both autistic individuals and sensors, avoiding corners. The last case is illustrated by the atelier (large room). In Appendix A, configurations (i), (ii), (iii), and (iv) models are reported in Figure A10. The reverberation time for configuration (i) was about 2.9 s at 1000 Hz and decreased at about 0.9 s when inserting pieces of furniture as configuration (ii) (Figure 13). For a complete description of the low frequency, readers may refer to Appendix A, Figure A11.