Murray Hodgson

This paper discusses acoustical quality in 17 healthcare office facilities. A subjective survey assessed office worker perceptions of their environments and satisfaction with the acoustics. Self-reported productivity, well-being, and health outcomes were also captured. Satisfaction was lower with acoustics than with other aspects of IEQ. Satisfaction results were related to room type and the absence or presence of a sound-masking system. Physical acoustical measurements were made in six types of rooms, some with sound-masking systems, to determine the acoustical characteristics, assess their quality and relate them to the building designs. Background-noise levels were measured in the occupied buildings. In the unoccupied buildings, measurements were made of reverberation times, and “speech” levels needed to calculate speech intelligibility indices for speech intelligibility and speech privacy. In open offices, sound-level reductions per distance doubling (DL2) were measured. The results are presented, and are related to room type and partition design. The knowledge gained from this study informs the decision-making of designers and facilities management for upgrades and future design projects.

The work reported here, part of a study on the performance and optimal design of interior natural-ventilation openings and silencers (“ventilators”), discusses the prediction of the acoustical performance of such ventilators, and the factors that affect it. A wave-based numerical approach—the finite-element method (FEM)—is applied. The development of a FEM technique for the prediction of ventilator diffuse-field transmission loss is presented. Model convergence is studied with respect to mesh, frequency-sampling and diffuse-field convergence. The modeling technique is validated by way of predictions and the comparison of them to analytical and experimental results. The transmission-loss performance of crosstalk silencers of four shapes, and the factors that affect it, are predicted and discussed. Performance increases with flow-path length for all silencer types. Adding elbows significantly increases high-frequency transmission loss, but does not increase overall silencer performance which is controlled by low-to-mid-frequency transmission loss.

Health-care facilities include many non-clinical office spaces for administrative staff; the role of acoustics in these spaces has been underexplored. This paper discusses the acoustical part of a study of indoor environmental quality (IEQ) in 17 healthcare office facilities. Physical acoustical measurements were made in six types of rooms, some with sound-masking systems, to determine the acoustical characteristics, assess their quality, relate them to the building designs, and develop prediction models. Background-noise levels were measured in the occupied buildings. In the unoccupied buildings, measurements were made of reverberation times, and “speech” levels needed to calculate speech intelligibility indices for speech intelligibility and speech privacy. In open offices, sound-level reductions per distance doubling (DL2) were measured. Noise isolations of internal partitions of different designs (double-plasterboard construction, modular or built in-situ, rising to the suspended ceiling or to the floor-ceiling slab, without and with doors, different amounts of glass) were measured. The acoustical characteristics were compared to design criteria to evaluate their acceptability. The results are presented, and are related to room type and partition design. An empirical model for predicting partition noise isolation, developed using regression techniques, is discussed. The knowledge gained from this study informs the decision-making of designers and facilities management for upgrades and future design projects.

Health-care facilities include many non-clinical office spaces for administrative staff; the role of acoustics in these spaces has been underexplored. This paper discusses the acoustical part of a study of indoor environmental quality (IEQ) in 17 healthcare office facilities. A subjective survey assessed office worker perceptions of their environments in general, and satisfaction with the acoustics. Self-reported productivity, well-being, and health outcomes were also captured. Satisfaction was lower with acoustics than with other aspects of IEQ. Satisfaction results were related to room type (e.g., open plan vs. shared vs. private office) and the absence or presence of a sound-masking system. Acoustics was the most important aspect of IEQ in predicting occupant satisfaction and well-being. Regression models were developed to predict workplace satisfaction, well-being, and job satisfaction from survey responses. Results of physical acoustical measurements showed very low correlations with subjective responses. The knowledge gained from this study informs the decision-making of designers and facilities management for upgrades and future design projects.

This study investigated the acoustical conditions in high-school Technology-Education Shops (TES) and the conflict that may exist due to their use at the same time as classrooms for learning and as industrial workshops for fabrication. This was done by measuring relevant acoustical characteristics in twenty TES in British Columbia when unoccupied with building services operating, and in ten of them when occupied and in normal operation with shop equipment running. The results were compared to existing acceptability/design criteria for classrooms and industrial workshops, related to background-noise level, teacher noise exposure, reverberation time, speech-intelligibility index (SII) and sound-level reduction with distance doubling (DL ₂ ), and pass/fail ratings were assigned. Noise levels and reverberation times in most unoccupied TES were higher than the acceptability/design criteria for core learning spaces. Teacher daily noise exposures in occupied TES were high and often exceeded regulatory limits. SII values often indicated ‘poor’ speech intelligibility for ‘normal’ and ‘raised’ vocal outputs, and ‘good’ speech intelligibility only for ‘loud’ and ‘shout’ vocal outputs. DL ₂ values were unacceptable in most of the TES. Most TES received a failing grade with respect to most evaluation criteria. The results confirm the existence of an acoustical conflict; the acoustical conditions in the TES as industrial rooms are generally unsatisfactory for their use as classrooms. In general, the results suggest that TES provide poor acoustical conditions, overexposing teachers and students to noise, and are in need of effective sound-design and noise-control measures.

Post-secondary institutions require appropriately designed informal learning spaces (ILSs) outside of classrooms for studying and group-work activities, but few studies have investigated how these spaces perform, especially in terms of acoustics. We measured objective acoustical characteristics and architectural features in 23 such spaces, and captured environmental assessments and well-being outcomes from a survey of 850 student occupants. Objective measures indicated that sound levels generated by occupants and other sound sources tended to exceed maximum values recommended by standards. Some components of perceived suitability and well-being were greater in spaces with lower background sound levels (e.g., from ventilation systems), but with more occupant-generated sound, and more reverberation. Furthermore, some design features such as more vegetation, the presence of soft furnishings, and lower seating density predicted some components of perceived suitability and well-being. This evaluation of ILSs offers lessons for designers and suggests additional directions for further study.

There is a need for a greater understanding of the acoustical and airflow performance of interior openings, and of silencers implemented to improve their acoustical performance, in naturally ventilated buildings. This paper discusses preliminary, fundamental aspects of a study done to provide engineers and architects with optimal design techniques. It discusses the characterization of ventilator performance, including the definition of the open area ratio - a combined acoustical and airflow performance-optimisation metric. This is calculated from conventional standardized metrics, takes a value of unity for a simple opening, and increases with increasing overall ventilator performance. Theory describing the open area ratio for ventilator characterization, and its limitations, are reviewed. Finally, to illustrate its benefits and capabilities, the proposed method is applied to the analysis of existing ventilator experimental results.