Investigation of Subjective Perception & Objective Metrics of Acoustic Room Diffusion

While a variety of assessment methodologies have been proposed to quantify acoustic diffusivity within rooms, a link between these and the perception of diffusion has not been fully established. This study investigated various ways of analyzing diffusion, through both human perception and objective metrics. Numerous impulse response measurements were collected from a physical acoustics testing facility designed for diffusion research. This space featured reversible absorptive/diffusive/reflective wall panels, which allowed numerous testing configurations. One such setup investigated how changing the diffusivity of an isolated wall surface impacted diffusive room conditions. Alternatively, the effects diffuser configurations had on diffusive room conditions were also explored. The collected room impulse response measurements were utilized in subjective trials and an objective metric analysis. In the subjective testing, room auralizations were presented to subjects in audio comparison trials to determine how well diffusive room conditions could be discerned. It was found that a significant quantity of diffusive surface area was required for the average subject to discriminate between the presented diffusive and absorptive wall conditions. Subjects were even less capable of discerning between the diffusive and reflective wall conditions presented. In addition, Male Speech was found to be more distinguishable than Violin Music, and musicians identified diffusive room conditions more effectively than non-musicians. The objective metric analysis identified the Number of Peaks as the most effective diffusive quantification methodology. Also, two metrics designed to measure reflection strengths within impulse responses were identified: Slope Ratio and the Degree of Time Series Fluctuations. Advisor: Lily M. Wan

Investigation of Subjective Perception & Objective Metrics of Acoustic Room Diffusion

While a variety of assessment methodologies have been proposed to quantify acoustic diffusivity within rooms, a link between these and the perception of diffusion has not been fully established. This study investigated various ways of analyzing diffusion, through both human perception and objective metrics. Numerous impulse response measurements were collected from a physical acoustics testing facility designed for diffusion research. This space featured reversible absorptive/diffusive/reflective wall panels, which allowed numerous testing configurations. One such setup investigated how changing the diffusivity of an isolated wall surface impacted diffusive room conditions. Alternatively, the effects diffuser configurations had on diffusive room conditions were also explored. The collected room impulse response measurements were utilized in subjective trials and an objective metric analysis. In the subjective testing, room auralizations were presented to subjects in audio comparison trials to determine how well diffusive room conditions could be discerned. It was found that a significant quantity of diffusive surface area was required for the average subject to discriminate between the presented diffusive and absorptive wall conditions. Subjects were even less capable of discerning between the diffusive and reflective wall conditions presented. In addition, Male Speech was found to be more distinguishable than Violin Music, and musicians identified diffusive room conditions more effectively than non-musicians. The objective metric analysis identified the Number of Peaks as the most effective diffusive quantification methodology. Also, two metrics designed to measure reflection strengths within impulse responses were identified: Slope Ratio and the Degree of Time Series Fluctuations. Advisor: Lily M. Wan

Evaluation of Hospital Soundscapes to Improve Patient and Staff Experience

Hospital soundscapes can be difficult environments to assess acoustically due to the continuous activity within units. Routinely, patients perceive these soundscapes poorly when rating their hospital experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In addition, hospital staff can be negatively impacted by the acoustical environments in which they work, affecting both performance and job satisfaction. This doctoral research addressed these issues across three phases by collecting acoustical measurements within three individual hospitals, comparing results with provided patient and staff survey information, and conducting laboratory tests of hospital noise perception. In the first two phases of this research, 38 patient rooms from 11 units within three hospitals were measured acoustically and correlated with HCAHPS ‘Quietness of the Hospital Environment’ surveys at room and unit-levels, revealing acoustical metrics linked to patient perceptions of hospital soundscape conditions. Metrics found to be most statistically correlated (p \u3c 0.05), included the absolute LAMIN levels in patient rooms, which found significantly higher HCAHPS ‘Quietness of the Hospital Environment’ scores in units with average LAMIN levels below 35 dBA. Many other standard acoustical metrics (such as LAEQ , LAMAX, LCPEAK, and LA90) were not found to be statistically correlated between measured acoustical data and HCAHPS ‘Quietness’ patient responses, emphasizing the difficulties faced when evaluating hospital soundscapes. The third phase of this research involved the creation and administration of a subjective perceptual laboratory test designed to assess the annoyance perception of hospital soundscapes with varying dynamic ranges of noise. It was found that subjects perceived soundscapes with a wider dynamic range of noise and louder peak noise events more negatively than soundscapes with a more consistent sound level. Taken as a whole, this study provides new insights into the potential relationships between hospital noise and patient and staff satisfaction. The three research phases aimed to address this issue from different perspectives to provide a broad assessment of this very complicated issue. The data gathered and presented could be utilized to more accurately assess hospital soundscapes and ultimately aid in the design process of new hospitals to improve patient and staff satisfaction

Evaluation of Hospital Soundscapes to Improve Patient and Staff Experience

Hospital soundscapes can be difficult environments to assess acoustically due to the continuous activity within units. Routinely, patients perceive these soundscapes poorly when rating their hospital experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In addition, hospital staff can be negatively impacted by the acoustical environments in which they work, affecting both performance and job satisfaction. This doctoral research addressed these issues across three phases by collecting acoustical measurements within three individual hospitals, comparing results with provided patient and staff survey information, and conducting laboratory tests of hospital noise perception. In the first two phases of this research, 38 patient rooms from 11 units within three hospitals were measured acoustically and correlated with HCAHPS ‘Quietness of the Hospital Environment’ surveys at room and unit-levels, revealing acoustical metrics linked to patient perceptions of hospital soundscape conditions. Metrics found to be most statistically correlated (p \u3c 0.05), included the absolute LAMIN levels in patient rooms, which found significantly higher HCAHPS ‘Quietness of the Hospital Environment’ scores in units with average LAMIN levels below 35 dBA. Many other standard acoustical metrics (such as LAEQ , LAMAX, LCPEAK, and LA90) were not found to be statistically correlated between measured acoustical data and HCAHPS ‘Quietness’ patient responses, emphasizing the difficulties faced when evaluating hospital soundscapes. The third phase of this research involved the creation and administration of a subjective perceptual laboratory test designed to assess the annoyance perception of hospital soundscapes with varying dynamic ranges of noise. It was found that subjects perceived soundscapes with a wider dynamic range of noise and louder peak noise events more negatively than soundscapes with a more consistent sound level. Taken as a whole, this study provides new insights into the potential relationships between hospital noise and patient and staff satisfaction. The three research phases aimed to address this issue from different perspectives to provide a broad assessment of this very complicated issue. The data gathered and presented could be utilized to more accurately assess hospital soundscapes and ultimately aid in the design process of new hospitals to improve patient and staff satisfaction