## 6 Conclusions  
Applying the prediction model for ambient noise levels (1) for eating establishments with the average parameters proposed by [PERSON] to calculate the acoustical capacity of the Nursing Home considered in this work might give misleading results. If no special consideration is made, the simplified formula (2) would return an acoustical capacity of 33 people (sufficient for the average occupancy of the living room), while the optimization of the model for the specific case led to a revised formula (3) that has the acoustical capacity of the investigated living room capped at 20 people (thus insufficient, if no correction is made on reverberation time). One of the limitations of this study is that its dataset currently does not differentiate between sound levels that are generated by verbal communication or rather other sound sources. Future works should possibly consider algorithms for sound sources recognition and separation to explain larger amounts of variance in the prediction models.  
For the investigated case, the model (1) for ambient noise levels was found to provide reasonably good prediction of measured data when the key parameters \(A_{p}\) and \(g\) are optimized. The main outcomes of the study are:  
* In the living room of a nursing home hosting people with BPSD, the prediction model gave the best results with a set of parameters that deviates considerably from those proposed for other eating establishments; namely, \(c=0.5\) dB/dB, \(A_{p}=0.2\) m\({}^{2}\) and \(g=9\);
* The admissible ambient noise level used as reference in determining the threshold for sufficient quality of verbal communication had to be adjusted to \(L_{\text{N,A}}=59\) dB to return realistic values of acoustical capacity for the living room;
* The acoustical retrofit intervention implemented in the living room of the AcustiCare case study increased the acoustical capacity of the space by 27 people, leading to a much lower occupancy saturation ratio under normal functioning conditions and an improved quality of verbal communication from \"insufficient\" to \"satisfactory\".  
Altogether, the findings of this study highlight the importance of having specific acoustic design criteria for care facilities, considering the potentially vulnerable groups of user that they host. Poor acoustic quality in such spaces might be detrimental to personal conditions for residents and exacerbate work-induced stress for staff. This work shows that there is scope to apply the acoustical capacity concept in nursing homes hosting older adults with dementia as a further design parameter to integrate with those that are conventionally used in general building and room acoustics practice; this will provide useful information for NH management about the number of residents a living space can comfortably accommodate, while guaranteeing good quality of verbal communication and less stress for both residents and staff.  
Conceptualization, F.A. and P.D.; methodology, F.A. and P.D.; formal analysis, F.A.; investigation, F.A., P.T., T.V.M., P.D.; resources, P.D., D.V.d.V., P.D.V., D.B.; data curation, F.A., P.T., P.D.; writing--original draft preparation, F.A.; writing--review and editing, all authors; supervision, P.D., M.P.; project administration, P.D.; funding acquisition, P.D., D.V.d.V., P.D.V., D.B. During the AcustiCare project [PERSON] was a post-doctoral researcher at Ghent University. All authors have read and agreed to the published version of the manuscript.  
The AcustiCare project is supported by the Flemish Agency for Innovation and Entrepreneurship (VLAIO) under the TETRA program for applied research (grant no. HBC.2016.0089).  
The authors are grateful to the staff members of the nursing homes, their residents and their relatives, the acoustic consultants and companies for their participation in the project.  
The authors declare no conflict of interest.