Open-plan Office Environments Research Articles

A Field Study of Individual, Energy-Efficient, and Human-Centered Indoor Electric Lighting: Its Impact on Comfort and Visual Performance in an Open-Plan Office Part 1

In this field study, we examined the impact of human-centered lighting on an open-plan office environment, involving the participation of sixty office workers. The objective was to investigate the effects of the Circadian Stimulus (CS) and Equivalent Melanopic Lux (EML) metrics. This study took place at Istanbul Technical University in Istanbul, Turkey. The office was equipped with single Correlated Color Temperature (CCT) light emitting diode (LED) sources, featuring two different light beam distributions: Direct Suspended Linear (L1) and Direct and Indirect Suspended Linear (L2). To minimize energy consumption, we proposed simulations for a suspended individual lighting system. The office workers were invited to complete visual cognitive performance tests, proofreading tasks, and the Karolinska Sleepiness Scale (KSS) test to measure alertness. Additionally, participants were asked to provide feedback on the comfort criteria associated with the designed human-centered lighting concept. The preliminary findings from part 1 of this field study shed light on the potential of office lighting modifications in enhancing energy efficiency and meeting the standards set by WELL v2 2023 Q4 and UL Design Guideline 24480 (2019). Part 2 of this study will further optimize the proposed lighting quality concept to determine the most suitable individual lighting solution for office workers.

How salutogenic workplace characteristics influence psychological and cognitive responses in a virtual environment

Until today, most research focussed on the effects of pathogenic workplace demands on employee illness instead of on salutogenic resources on health. Using a stated-choice experiment in a virtual open-plan office, this study identifies key design aspects that enhance psychological and cognitive responses, ultimately improving health outcomes. The study systematically varied six workplace attributes: screens between workstations, occupancy rate, presence of plants, views outside, window-to-wall ratio (WWR), and colour palette. Each attribute predicted perceptions of at least one psychological or cognitive state. Plants had the highest relative importance for all expected responses but views outside with ample daylight, red/warm wall colours, and a low occupancy rate without screens between desks were also important. Low-cost interventions like adding plants, removing screens, and using warm wall colours can contribute to a healthier open-plan office environment. These insights can guide workplace managers to design environments that support employees’ mental states and health. Practitioner summary: Salutogenic workplace resources that promote health have been understudied. This study aimed to show which workplace characteristics caused positive psychological and cognitive responses to improve health, using a stated-choice experiment in a virtual office environment. Plants in the office were the most important attribute for employees’ psychological and cognitive responses.

Acoustic assessment of an open-plan office environment against the newly published ISO 22955 acoustic parameters

This paper aims to assess the acoustic performance of an existing open-plan office environment with suspended sound absorbers below a hard reflective ceiling and low workstation dividers against the newly published ISO 22955 acoustic parameters. The room acoustic variables, such as sound absorption, screens between workstations, speech masking sounds and room dimensions all interact in a complex way affecting the values of single-number quantities presented in the ISO 22955 standard. In order to determine the in-situ performance, acoustic measurements were carried out on site. Odeon room acoustic prediction software was utilised to assess the efficiency of various acoustical remedies such as free hanging sound absorbers, wall to wall sound absorbing ceilings, dividers between work areas and increased height of dividers between workstations. The results from the in-situ room acoustic measurements demonstrate that the required value as described in the ISO 22955 standard is not easily achievable in the open-plan office environment without dividers with sufficient height between workstations and modest room acoustic features. The acoustic modelling results confirmed that the required level for the open-plan office, in terms of the ISO 22955 standard, is only attainable with a combination of room acoustic variables that go against modern interior designs.

An online survey on self-reported workplace design and personal factors concerning speech privacy satisfaction in open-plan office environment

This study used a questionnaire survey to investigate self-reported workplace design and personal factors’ relationships with speech privacy satisfaction. First, we analysed the correlations of self-reported workplace design and personal factors with speech privacy satisfaction levels. Next, we investigated the relative contribution of each workplace design and personal factor through a stepwise regression analysis and a general linear model. Among the workplace design factors, self-reported data on seating type and partition height had the most significant correlations with the satisfaction levels of speech privacy. Meanwhile, among the personal factors, overhearing, task disturbance, noise sensitivity, attitude, space modifiability, and behavioural coping were significantly correlated with speech privacy satisfaction levels. The stepwise regression analysis and general linear model indicated that task disturbance, space modifiability, and behavioural coping contributed more to satisfaction with speech privacy than other factors.

From luminance to brightness: A data-driven approach to support brightness assessments in open plan offices

People can instantly distinguish a brighter from a darker environment, but it is still unknown how to estimate brightness from the luminance distribution in complex visual scenes. In this study, we performed a meta-analysis of three experiments in which participants assessed brightness in an open plan office environment. Experiment 1 varied the luminance distribution on the wall, Experiment 2 varied the desk illuminance and Experiment 3 varied the ceiling illumination. Correlating various measures derived from high-resolution luminance images with participants’ brightness ratings, we investigated to what extent brightness could be predicted. In particular, we focused on 19 different luminance distribution characteristics calculated over 11 different areas of the visual field. In line with earlier work, participants could be grouped in two categories, one consisting of participants who substantially and consistently varied in their brightness assessments for the different settings, and the other consisting of participants who responded more evenly, regardless of the setting. Based on the brightness-responsive group of participants, brightness could be best modelled with the logarithm of the median luminance calculated over a 60° horizontal band in the field of view or with the logarithm of the 95th percentile over the median calculated over the 40° horizontal band, explaining, respectively, 38% and 35% of the variance in brightness perception.

Crossed effects of audio-visual environment on indoor soundscape perception for pleasant open-plan office environments

An open-plan office (OPO) layout promotes communication and teamwork among workers and provides flexibility in working; however, it also adversely affects work satisfaction, health, and worker privacy, leading to dissatisfaction and poor task performance. In this study, the subjective responses in an audio-visual OPO environment were analyzed to investigate the effects of the environment on indoor soundscape perception for designing pleasant OPOs. The outdoor environments of four OPOs with four different visual layouts were divided based on two conditions with different window views (good and bad views) to model eight visual stimuli. The auditory aspect was evaluated by computer simulation using three sound sources. For subjective assessment, virtual reality technology was employed with 24 audio-visual stimuli, and thirty-four subjects were asked to rate the perceived affective quality and overall quality. Task performance was quantified using auditory digit span tasks. The spatial preference decreased with the Loud, Variable, and Reverberant attributes and increased with the Bright, Orderly, and Wide attributes. For the same OPO soundscape, the window area ratio and floor area showed positive correlations with visual privacy, visual satisfaction, speech privacy, and sound satisfaction. However, work satisfaction and task performance exhibited contradictory relationships with the visual parameters. Furthermore, wide, open workspaces yielded high work satisfaction, whereas narrow, confined work spaces yielded high task performance. These results indicate that the relationship between work satisfaction and task performance must be considered for a balanced OPO design, providing practical guidance for designing pleasant OPO environments.

Against a workplace contagion: a digital approach to support hygiene-conscious office space planning

PurposeThis research presents a multi-objective optimization approach to integrate spatial planning measures in open-plan office environments in order to lower the risk of a workplace contagion. These measures were gathered, formalized, parameterized, and coded and integrated into a digital tool.Design/methodology/approachTo demonstrate the research's approach, a simple design problem was designed, explored, and the results were evaluated. The researchers assumed an empty open office space, with the windows and doors (as exits and/or as access to amenities) already in place (Figure 1). The aim is to optimize the space planning, with the following objectives in mind: maximize the number of employees in a floor while maintaining physical distancing recommendations for avoiding infections; no face-to-face or back-to-back seating positions are allowed; maximize physical access to windows for natural ventilation; minimizing areas with potential “congestions” in the space, i.e. areas susceptible to overlapping foot traffic from numerous employees, which increases the potential for close encounters and minimizing the travel distance from the employee's desk to all neighbouring desks, hence reducing the foot traffic in the space. In the experiment, the following was assumed: the workspace layout is rectangular, the workstation desks are rectangular, the seating area, windows, and access to exits and amenities are well-defined.FindingsIt was found that configurations with desks parallel to the longer side of the space provided more employee capacity; however, they usually performed poorer in terms of the buzz score. On the other hand, configurations with desks perpendicular to the longer side of the space had, on average, better buzz scores, usually at the cost of the reduction of the number of potential employees. There was however one alternative in the latter set of configurations, which achieved above-average buzz and adjacency scores, and the potential to accommodate 56 employees, one of the highest capacities for employees in the solution space (the highest being 60). Designers could explore the design space further to make sure it complies with these basic spatial rules for mitigating the spread of infections, while experimenting with the workspace layout.Research limitations/implicationsIt is important to note that in order for a designer to handle any given design problem even with the aid of a computer system, it is important to provide a set of initial conditions and assumptions and a set of variables. In the universe of all possible variables, the designer can pick a number of variations of the initial conditions and run parallel experiments to compare their outcomes. In the experiment demonstrated here the following was assumed. The workspace layout is rectangular with predefined entrances/exits. Free flow of employees is allowed. No pre-set one-way paths. The workstation desks are rectangular. The seating area windows and access to amenities are well-defined.Originality/valueThis research presented a digital optimization approach to enhance the spatial planning process in open-plan office spaces, with the aim of mitigating the risks of infectious diseases' transmission. Spatial design considerations were gathered from literature and formalized as design objectives and constraints, then further parameterized and represented as numerical values and scores for objective evaluation. The design parameters, constraints and calculations to derive the scores for the designated design objectives were coded into a digital tool that can receive a building information model (BIM) model of an office space and provide preliminary furniture plans using a multi-objective optimization (MOO) approach. It is obvious that the furniture layouts that can be considered “acceptable”, based on this approach, are not considered “ready-to-implement” solutions, because designers need to integrate a multitude of other design factors in their design. This approach can still, however, be useful to help the designer integrate spatial considerations for slowing down a contagion.

A Socio-Technical Perspective on the Application of Green Ergonomics to Open-Plan Offices: A Review of the Literature and Recommendations for Future Research

Open-plan office (OPO) layouts emerged to allow organizations to adapt to changing workplace demands. We explore the potential for OPOs to provide such adaptive capacity to respond to two contemporary issues for organizations: the chronic challenge of environmental sustainability, and the acute challenges emerging from the great COVID-19 homeworking experiment. We apply a socio-technical systems perspective and green ergonomics principles to investigate the relationship between an OPO environment and the occupants working within it. In doing so, we consider relevant technical and human factors, such as green technology and employee green behavior. We also consider how a green OPO might provide non-carbon benefits such as improving occupant well-being and supporting the emergence of a green organizational culture. Our investigation highlights several avenues through which an OPO designed with green ergonomic principles could benefit occupants, the organizations they work for, and the natural environment of which they are a part and on which they depend. We find reason to suspect that green OPOs could play an important role in sustainable development; and offer a research agenda to help determine whether it is true that OPOs can, indeed, exemplify how “going green” may be good for business.

Open-plan office noise is stressful: multimodal stress detection in a simulated work environment

AbstractThe coronavirus disease 2019 (COVID-2019)-induced changes in the workplace present a timely opportunity for human resource management practitioners to consider and remediate the deleterious effects of noise, a commonly cited complaint of employees working in open-plan office (OPO) environments. While self-reports suggest that OPO noise is perceived as a stressor, there is little experimental research comprehensively investigating the effects of noise on employees in terms of their cognitive performance, physiological indicators of stress, and affect. Employing a simulated office setting, we compared the effects of a typical OPO auditory environment to a quieter private office auditory environment on a range of objective and subjective measures of well-being and performance. While OPO noise did not reduce immediate cognitive task performance compared to the quieter environment, it did reduce psychological well-being as evidenced by self-reports of mood, facial expressions of emotion, and physiological indicators of stress in the form of heartrate and skin conductivity. Our research highlights the importance of using a multimodal approach to assess the impact of workplace stressors such as noise. Such an approach will allow HR practitioners to make data-driven recommendations about the design and modification of workspaces to minimize negative effects and support employee well-being.

Image-Based Indoor Topological Navigation with Collision Avoidance for Resource-Constrained Mobile Robots

This paper presents a complete topological navigation system for a resource-constrained mobile robot like Pepper, based on image memory and the teach-and-repeat paradigm. Image memory is constructed from a set of reference images that are acquired during a prior mapping phase and arranged topologically. A* search is used to find the optimal path between the current location and the destination. The images from the robot’s RGB camera are used to localize within the topological graph, and an Image-Based Visual Servoing (IBVS) control scheme drives the robot to the next node in the graph. Depth images update a local egocentric occupancy grid, and another IBVS controller navigates local free-space. The output of the two IBVS controllers is fused to form the final control command for the robot. We demonstrate real-time navigation for the Pepper robot in an indoor open-plan office environment without the need for accurate mapping and localization. Our core navigation module can run completely onboard the robot (which has quite limited computing capabilities) at 5 Hz without requiring any external computing resources. We have successfully performed navigation trials over 15 days, visiting more than 50 destinations and traveling more than 1200m with a success rate of over 80%. We discuss remaining challenges and openly share our software.

The effects of masking sound and signal-to-noise ratio on work performance in Chinese open-plan offices

A laboratory experiment has been carried out in this paper to study the effects of masking sound and signal-to-noise ratio (SNR) on occupants’ objective performance and perceived sound environmental quality in Chinese open-plan offices. The serial recall task performance and subject perceptions of 30 participants were tested under 14 different acoustic conditions, including “Quiet” (the condition without neither masking sound nor speech noise), “Speech_only” (the condition without masking sound but with speech noise), and 12 masking sound conditions. In these masking sound conditions, 4 masking sources (speech-like pink noise, air-conditioning noise, spring water sound and babble) were used and each source was given under 3 levels of SNR (i.e., small (−6.6 to −5.5 dB), medium (−3.0 to −2.3 dB) and large (4.4–4.8 dB) levels). The results demonstrate: (1) the effects of masking sound environment on occupants’ objective performance and perceived sound environmental quality (including acoustic satisfaction, perceived disturbance and subjective workload) can significantly differ by masking source and SNR, (2) spring water sound at medium SNR (SNR = −2.4 dB) is the best condition among the tested 12 masking sound environments, and (3) the effects of masking sound on occupants may differ by their individual factors, such as gender, educational level and noise sensitivity. According to the authors’ knowledge, this study is the first attempt to study the effects of masking sound and SNR on work performance in Chinese-language open-plan office environments. The findings can be used as a reference for the acoustic research and design of Chinese open-plan offices.

Sickness absence and sickness presence in relation to office type: An observational study of employer-recorded and self-reported data from Sweden.

ObjectivesPrevious research suggesting that open-plan office environments are associated with higher rates of sickness absence rely on self-reports which can be affected by recall bias. This paper investigates the associations of sickness absence, obtained from employer records as well as self-reports, with office type (cell offices and different sizes of open-plan offices). It additionally studies whether office type is associated with sickness presence.MethodsEmployees from two private and one public sector organization were recruited to the study. Office type was ascertained by direct observation or from employee responses to an online survey. Control variables were gender, age, public/private sector and education level. Number of days and episodes of sickness absence were calculated from employer absence records and regressed on office type using negative binomial regression (n = 988). Self-reports of sickness absence and presence were regressed on office type using ordered logistic regression (n = 1237).ResultsOffice type was generally not associated with employer records of number of episodes or days of sickness absence, except that the total number of days of leave was higher in flex offices compared to cell offices (IRR = 2.46, p = 0.007). In general, office type was not associated with self-reported days of sickness absence, apart from participants working in medium-sized open-plan offices who had 0.42 higher log-odds of absence than those working in cell offices (p = 0.004). Office type was not associated with self-reported sickness presence.ConclusionsOffice type was not associated with sickness presence nor, in general, with sickness absence, whether obtained from self-reports or company records. It is not possible to conclude from this study that open-plan offices are associated with greater sickness absence or sickness presence compared to cell offices.

Open plan office space? If you're going to do it, do it right: A fourteen-month longitudinal case study

There are compelling findings that open-plan office environments are associated with declines in employee wellbeing. In spite of this, the move towards shared office environments continues; yet there is a lack of research describing open-plan offices that have positive outcomes for workers. We describe a “best practice” open-plan fit-out of a law firm and provide data from occupants relating to their performance, well-being, and collegial relationships. Six months after moving to an open-plan office, staff were anonymously surveyed, and 24 were interviewed. Fourteen months later, occupants responded to a follow-up survey. Positive outcomes relating to aesthetics, collegiality, and communication were achieved through good technical design and thoughtful ergonomic assessment of the needs of employees and the requirements of their tasks. A gender difference emerged whereby female, but not male, workers in this environment reported feeling observed. This has implications for the relatively different impact these environments may have on workers. Thus, by following ergonomic principles to create open-plan offices that are ‘safe by design’ organizations can ameliorate many of the negative consequences associated with these environments.

An experience sampling approach to the workplace environment survey

PurposeThe purpose of this study is to pilot test the effectiveness of the experience sampling approach for measuring employee satisfaction with the workplace environment. Additionally, the authors also aimed to explore, which aspects of environmental comfort have the strongest impact on momentary well-being and productivity.Design/methodology/approachIn total, 15 knowledge workers in an open-plan office environment were sent a brief survey (measuring environmental comfort, momentary well-being and perceived productivity) each day over an 11-day study period and provided 78 individual survey responses in total.FindingsAll but one of the measures on the survey had low test-retest reliability, indicating that employees’ experiences of environmental comfort varied significantly each time they completed the survey. Additionally, higher environmental comfort was associated with improved well-being and productivity.Practical implicationsThe results suggest that an experience sampling approach to the workplace occupant survey is justified to better capture the temporal variability in experiences of environmental comfort. The results also suggest that improving environmental comfort, particularly by reducing the level of distractions, will enable employees to work more productively.Originality/valueTo the best of the authors’ knowledge, this is the first field study which has attempted to directly address limitations in traditional occupant surveys by using an experience sampling approach rather than a one-time-only questionnaire.

The effects of workstation partition heights on employees’ perceptions in open-plan offices

PurposeThe purpose of this paper is to determine the effects of environmental factors in open-plan offices with the same characteristics but with different workstation partition heights (1.10, 1.40 and 1.65 m) on perceptual evaluations of office employees.Design/methodology/approachIn this research, the effects of environmental factors on employees’ perceptual evaluations in open-plan offices at the Gölbaşı Region of Ankara were measured with a detailed questionnaire. The research data were obtained from 81 employees who agreed to fill out the questionnaire and who use open-plan offices.FindingsIt was found that the office environments with 1.65 m workstation partition heights were more favorably assessed for each of the items of planning and of privacy that form the dependent variables compared to the office environments with 1.10 and 1.40 m partition heights. On the other hand, the office environments with the 1.10 and 1.40 m partition heights were more favorable for lighting items than the 1.65 m partition height office environments. In addition, young employees had a more positive tendency toward the perceptions of environmental factors, including different workstation partition heights in open-plan offices, compared to older employees.Research limitations/implicationsResults of this research provide a fundamental contribution for the impact of various partition heights that have substantial implications on the perceptions of open-plan office environments. At this point, as open-plan offices have important effects on the quality of employees’ work experiences, the influence of various partition heights on the performance of employees should be emphasized in future studies. The diversity of performance (reading comprehension, calculation, design, drawing, etc.) will be an important decision.Originality/valueThe significant contribution of this research is that it provides valid data and makes a valuable contribution to the body of knowledge in open-plan office design.

Does the Number of Occupants in an Office Influence Individual Perceptions of Comfort and Productivity?—New Evidence from 5000 Office Workers

Purpose—The purpose of this article is to present evidence of occupants’ perception of their work environment in five different office types (Solo, Duo, 2–4, 5–8 and 8Plus offices). The study examined the influence of the number of office occupants on individual perception of indoor environment quality (IEQ) in office environments. Design/methodology/approach—A dataset of 5000 respondents in 67 commercial and institutional office buildings was analysed using IBM SPSS v23. The dataset contained user response on the BUS Methodology questionnaire that is designed to retrieve occupants’ perception of their work environments. Analysis of Variance (ANOVA) and multiple regression analysis were conducted to calculate the impact of the office environment on occupants’ perception of comfort and productivity. Findings - This study showed that occupants in Solo and Duo offices perceived higher satisfaction with their environment (except for temperature in summer), better health and productivity; and more control over the office environment than those in 5–8 and 8Plus offices. Occupants in 8Plus offices were most satisfied with the temperature in summer. It was also noted that the IEQ factors that predicted comfort were observed to not predict productivity. Noise was the only IEQ factor that had predictive power for both comfort and productivity in all the office spaces. Originality/value—This article provides intriguing findings on occupants’ perception of various types of office environment that contributes significantly to the debate on open-plan versus cellular office environments.

ReViCEE: A recommendation based approach for personalized control, visual comfort & energy efficiency in buildings

Built-environment, especially open-plan workplaces are often not tailored to meet individual visual comfort needs. Therefore, meeting the need for personalized visual comfort whilst achieving energy efficiency in open-plan office environment has been an open challenge. However, recent technological advancements in distributed sensing, pervasive computing, context-awareness and machine learning is progressively closing this gap. This article introduces ReViCEE–a simple recommender systems based approach to learn both individual and collaborative user-preferences from historical data and offer recommendations for intelligent building lighting controls. The intelligence in this case is achieved by being able to derive set-points to control task lights such that it balances personalized visual comfort without compromising on energy savings. The proposed approach has been developed using Python and implemented on a real test-bed in an university campus office building in National University of Singapore. The evaluation of the proposed approach is carried out for two months using field experiments involving distributed wireless sensor actuator network (WSAN) and multiple occupants having varied visual sensation. The novelty lies in proposing a new inter-disciplinary approach that supports smart and intelligent buildings paradigm by learning and predicting optimum individual user-preferences towards energy efficient control of personalized light. The results obtained from field experiments present a potential energy savings upto 72% when compared to the conventional lighting systems used.

Acoustic Issues in Open Plan Offices: A Typological Analysis

This paper reports the acoustic issues of open plan office environments. According to a detailed research based on the scientific literature of the most suitable acoustic descriptors recommended for the open plan offices analysis, the main typological-functional configurations of these environments have been analyzed in order to identify six spatial typologies. The variation of acoustic parameters of these typologies has been evaluated by using a sound pyramid tracing software. The analysis procedure was calibrated in a case study of an office environment, where a measurement campaign was carried out. Results point out that the acoustic improvement of open plan offices can usually be achieved by introducing a sound absorbing false ceiling and dividing panels between working positions, but there are different issues depending on spatial geometries of the office. Better results are referred to office typologies characterized by reduced height and equal plan dimensions.

The irrelevant speech effect in multi-talker environments: Applications to open-plan offices

Irrelevant speech from co-workers has consistently been listed as one of the major nuisances within open-plan work environments. To explore the psychoacoustic basis of the so-called irrelevant speech effect (ISE; which causes cognitive decline and increases acoustic distraction) within a multi-talker context, a series of laboratory-based experiments were run. These experiments used room acoustical simulations of various open-plan office environments within a climate-controlled chamber to test several factors relevant to the ISE. These factors included the number of simultaneously active talkers, their spatial arrangements, sound pressure levels and the semanticity of speech. The main findings thus far indicate that multi-talker speech lead to a stronger ISE than speech from a single talker, which further interacts with the overall sound level, semanticity, etc., to exhibit a more complicated effect than what has been proposed in previous studies. The effect of the number of active talkers alone suggests reconsiderations of some assumptions in the ISO 3382-3. More generally, the perception of speech “babble” seems to be affected by multiple factors in a realistic working environment. Some of our research is directly related to characterising speech babble and its function as a beneficial sound masker in multi-talker environments.Irrelevant speech from co-workers has consistently been listed as one of the major nuisances within open-plan work environments. To explore the psychoacoustic basis of the so-called irrelevant speech effect (ISE; which causes cognitive decline and increases acoustic distraction) within a multi-talker context, a series of laboratory-based experiments were run. These experiments used room acoustical simulations of various open-plan office environments within a climate-controlled chamber to test several factors relevant to the ISE. These factors included the number of simultaneously active talkers, their spatial arrangements, sound pressure levels and the semanticity of speech. The main findings thus far indicate that multi-talker speech lead to a stronger ISE than speech from a single talker, which further interacts with the overall sound level, semanticity, etc., to exhibit a more complicated effect than what has been proposed in previous studies. The effect of the number of active talkers alone suggests r...

Auditory distraction in open-plan office environments: The effect of multi-talker acoustics

Within the soundscapes of open-plan offices, irrelevant speech has consistently been reported as the most distracting, and causing performance decrements for workers. Notwithstanding this generalization, the ‘babble’ created by multiple simultaneously active talkers can sometimes provide beneficial sound masking, but due to spatial release from masking (SRM), speech may still be sufficiently intelligible up to a certain number of talkers (estimated to be about four). This was explored within a highly-realistic office simulation, where the cognitive performance, and subjective distraction of participants were tested. The experimental design was a 4×2 factorial (4 talker numbers, 2 levels of broadband sound masking, as the factors). The results indicated that within lower sound pressure level (SPL) of broadband sound masking, multi-talker sound environments degraded cognitive tasks performance more than those with a single talker, suggesting SRM effects. For higher SPL broadband sound masking, the cognitive test scores were similar within the different talker numbers. The subjective distraction increased monotonically with the number of talkers, with higher distraction within lower SPL broadband sound masking. Overall, the results call into question the single talker assumption (being the most distracting) within the international standard for measuring open-plan office acoustic environments (ISO 3382-3:2012). Soundscapes with 4 simultaneous talkers were still not adequately providing beneficial ‘babble’ masking, and were more distracting than 1 active talker. In conclusion, it is suggested that the acoustics environment of open-plan offices needs better characterization by incorporating some of the complexity and psychoacoustics of multi-talker scenarios.