Developing evidence based design metrics and methods for improving healthcare soundscapes
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Healing and clinical work requires a complex choreography of architectural acoustic design in healthcare settings. In most healthcare settings, medical staff members conduct vital tasks that may have life-and-death implications. Patients visit the hospitals to heal. Their expectations include fast recovery, restful sleep, and privacy (i.e., speech privacy). However, sound environment qualities of the care settings often fall far from supporting the mission of hospitals. There is strong and growing evidence showing that effective soundscapes in healthcare settings potentially impact errors, healing and stress for patients, families and staff but it is still not clear what measures of the sound environment best predict key healthcare outcomes and what design strategies best impact those measures. By using a multi-method approach (i.e., objective and subjective noise level measurements, in-situ impulse response measurements, heuristic design analysis, theoretical studies, acoustic simulations and statistical analysis), this study aims to develop evidence based design strategies by statistically defining the relationships between three types of variables: (1) architectural floor-plate design metrics, (2) acoustic metrics, and (3) occupant response. The research is conducted in three phases. The first phase of the study compared the objective and subjective qualities of the hospital sound environments with different architectural designs, assessed the effectiveness of a newer acoustic metrics in capturing caregiver perceptions, and evaluated the impact of particular noise sources on caregiver outcomes. The second phase of the study tested the validity of an acoustic simulation tool in estimating the acoustic qualities of the healthcare soundscapes. The third phase of the study systematically explored the relationship between floor-plate design and acoustics of complex inter-connected nursing unit corridors. Even though the relationship between design and acoustics of proportional spaces (a.k.a. rooms with more traditional dimensions) has been well documented, the number of studies linking design and acoustics of complex non-proportional spaces such as inter-connected corridors still remains limited. The findings of the first phase show that critical care sound environments with different designs can vary drastically and impact caregivers` perceived wellbeing and task performance (e.g., patient auditory monitoring). Despite their extensive use, traditional noise metrics sometimes may not be effective in capturing unique characteristics of healthcare sound environments. This study validated the effectiveness of a new more detailed noise metric, "occurrence rate", in capturing the differences between acoustic characteristics of healthcare sound environments. Moreover, particular noise sources such as impulsive noises are likely to dominate the ICU sound environments and interfere with perceived caregiver health and performance. The findings of the second phase suggest the potential effectiveness of acoustic simulation tools (with hybrid prediction programs) in estimating the acoustic qualities of complex inter-connected hospital corridors. The findings of the third phase suggest the potential significant impact of design features of particular hallways (e.g., number of turns, corridor length, and number of branches) and overall floor-shape characteristics of inter-connected corridors (i.e., relative grid distance, and visual fragmentation) on reverberation time. Overall, in the units with shorter, more compact, fragmented corridors with multiple number of branching hallways, reverberation times are likely to be less. Moreover receivers located at the corridors with less number of turns from the sound source also potentially experience lower reverberation times. According to previous research, the human auditory system`s ability to monitor auditory cues is likely to be higher in the less reverberant sound environments.