# Indoor Acoustic Requirements for Autism-Friendly Spaces
## 4 Conclusions  
Recent statistics highlight how autism diagnoses have been growing in years; their life expectancy demonstrates that they could be strongly dependent on parents and care facilities for a very long period of life. Indoor environmental assistive technology matched with inclusive design represents a valid support in order to achieve autonomy for them, their families, and caregivers. The sound field can be implemented to best accommodate the needs of autistic people with hearing impairment or hypersensitivity to sound and at the same time, the requirements of the noise sensors. In this work, the use of (i) a wide literature review, (ii) measurements and investigations on real premise, and (iii) the use of 3D acoustic simulations, demonstrate that the indoor sound field, achievable with furniture or with sound absorbing materials distribution, has to be optimized from the point of view of acoustic sensors and the needs of autistic users. To this aim, in order to achieve better acoustic spatial requirements, it is first imperative to evaluate in detail what are the likes and dislikes of individuals on the autistic spectrum. Then, it is important to estimate the positioning modalities and locations of the necessary sound absorbing surfaces. At the same time, the size of the room influences the decision process. Therefore, from a vast literature review, important results are identified and could be resumed as follows:  
* the literature presents many lacks on the autistic individuals' indoor sound field requirements. However, the literature only provides some ranges for sound devices;  
Figure 16: Definition D\({}_{50}\) for atelier for configurations (**iii**) with the sound absorbing surface distributed only on the ceiling (left-graduation range from purple = 0.89 o red = 1 s), (**iv**) with the sound absorbing surface distributed partially on corners and partially on the ceiling (right-graduation range from purple = 0.92 to red = 1). Spatial distribution at 1000 Hz. Figure 15: Definition D\({}_{50}\) for atelier for configurations (**i**) empty room (left-graduation range from purple = 0.44 to red = 0.96), (**ii**) room with furniture (right-graduation range from purple = 0.81 to red = 1). Spatial distribution at 1000 Hz. in the present literature, no indoor acoustic requirements have been found to be dedicated to autistic individuals. Some works deal with hearing and learning impaired people's necessities; and
* no indoor sound field distribution study is present nor for sound sensors, neither for individuals on the autism spectrum. Given the above-mentioned conclusions, this research is able to provide the following new findings: reverberation time RT, clarity C\({}_{50}\), and D\({}_{50}\) are the identified acoustic objective parameters, capable to consider both the sensors and individuals' indoor requirements. The best ranges for indoor sound field, considering both the requirements for sound devices and ASD individuals are in the octave frequency range of 500 Hz, 1000 Hz, and 2000 Hz: 0.4 s \(\leq\) RT \(\leq\) 0.7 s; C\({}_{50}\geq\)2 dB; D\({}_{50}\geq\) 0.7; sound absorbing areas affect sensor positioning, visual aspects, indoor requirements, and sound field distribution. For this reason, for small rooms, regardless of the destination (medical, residential, etc. ), a continuous absorbing ceiling is to be preferred in comparison to discrete surfaces. In the case of large rooms, the opposite has to be favored.