Jiajing Li, School of Architecture, Tsinghua University

Si Zhang, School of Architecture, Harbin Institute of Technology; Key Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and Technology, Ministry of Industry and Information Technology

Abstract

Background: Noise is a meaningless sound signal, which may affect users’ work and attention in the environment. Based on previous research, open-plan office often results in higher noise level, raising distraction and annoyance, which are the two main indicators for users’ subjective acoustic satisfaction and may lowering their work performance and efficiency. Therefore, enhancing employee’s acoustic satisfaction in the open-plan office through environment intervention has been a critical issue in research and design practice. However, there is rare study on factors that influence acoustic satisfaction in open-plan office for academic researchers.

Purpose: To explore the relationship between subjective noise experience (distraction and annoyance) of researchers in open-plan office and their spatial privacy, coping strategies, and types of work.

Design and Methods: An open-plan office for researchers in a university was selected as the study site. Sound parameter was collected in different scenes of the day and generated based on different types of noise in the office. Subjective noise experience, coping strategies and open-ended suggestions were collected through a questionnaire. Mean Value method, t-test and Pearson Correlation.

Results: The correlation between spatial privacy and noise experience was not approved by the data. Control of annoyance and distraction have strong correlation with perceived noise and noise experience. Noise effects when doing different types of work were significantly different, meeting and entertaining appeared to perceive less negative experience than reading and writing, under the same level of noise. Major types of noise that led to performance declining and users’ suggestions were also analyzed.

Four design strategies aiming at enhancing the subjective noise experience were generated for open-plan offices for researchers, including setting up partition, designing separate spaces for meeting, using signage and users’ regulation, and providing noise control utilities.

Keywords: noise effects, open-plan office, distraction, annoyance, privacy, control, researchers

Introduction

Literature Review

Noise is sound signal without information because it begins to question the content of sound in relation to acoustic satisfaction. Noise within workplace tends get more and more attention in the following two perspectives: 1) Altitude of employees towards noise in the office 2) Work performance in relation to office noise.

Altitude of Employees towards Noise in Office. Noise is identified as an ambient stressor relating to job satisfaction in the work environment. Longitudinal field study (Kaarlela-Tuomaala, Helenius, Keskinen, & Hongisto, 2009) shows that negative effects of acoustic environment increased significantly, including increased distraction, reduced privacy, increased concentration difficulties and increased use of coping strategies. As a result of the use of the open-plan office, architectural privacy and psychological privacy have declined. Although the open-plan office could increase architectural accessibility and social, the study shows that privacy is more important than accessibility for employees’ satisfaction(Brennan, Chugh, & Kline, 2002). Annoyance and distraction were the two main subjective responses to noise(Navai & Veitch, 2003).

Work Performance in Relation to Office Noise. Noise is one factor that may undermine the expected efficiency and productivity gains. Evidence indicates that participants remembered fewer words, rated themselves as more tired, and were less motivated with work in noise compared to low noise(Jahncke, Hygge, Halin, Green, & Dimberg, 2011). Studies have shown that when sound is turned off, errors in work are reduced and productivity increases(Kamarulzaman, Saleh, Hashim, Hashim, & Abdul-Ghani, 2011). Office noise leads to increased perceived exertion in the head, but not to significant physiological stress reactions under the short-term exposure conditions of the present study (Kristiansen et al., 2009). The impact of noise on work performance is related to the content of the task. Noise disturbes most work, including reading, writing or processing(Kaarlela-Tuomaala et al., 2009). Both high-intensity and low-intensity office noise can cause stress among experienced clerical workers(Evans & Johnson, 2000).

What’s more, as jobs become more technologically complex, the frequency of stress-related disorders in work environments increases. More personal control over the physical workspace (e.g., adjustment) and easy access to meeting places led to higher perceived group cohesiveness and job satisfaction(Lee & Brand, 2005). Environmental control can be said to affect workers on at least two levels: mechanical or instrumental control, and empowerment(Vischer, 2007).

Research Objects

Based on the above review, noise is a subjective experience and acoustic satisfaction is a psychophysical construct. Annoyance and distraction were the two main subjective experiences to noise. Thus, the present research aims to focus on how the noise of open-plan office affects researchers subjective experiences and how the users’ coping strategies affect the experiences. Three hypotheses were generated:

Hypothesis 1: People have more spatial privacy feel less distracted and less annoyed under the same level of noise.

Hypothesis 2: People have more coping strategies feel less distracted, less annoyed under the same level of noise, and greater sense of control. People have more coping strategies feel greater sense of control. People have greater sense of control feel less distracted and less annoyed under the same level of noise.

Hypothesis 3: When doing reading and writing, people feel more annoyance and distracted compared to meeting, entertaining and resting, under the same level of noise.

Methods

Site Description

The present research chose S Office as the experimental site. S Office is an open-plan office for staff, research assistant, teaching assistant and visiting scholar of H center in T University. The center provides the office for them to work better. However, many researchers prefer to work in the nighttime. According to their informal oral report, the reason for the low performance is mainly the noise. Therefore, this research aims to learn the noise effects for the researches in the open-plan office.

S office provides 40 desks, among which 30 are used frequently. Except for one corner desk, the rest of them are all rectangular desks. According to type and material of the partitions, desks can be divided into 4 types, shown in Figure.1.

The participate of this research was research assistants, teaching assistants and visiting scholars who mainly conduct research work in the open-plan office. Staff mainly deals with non-research affairs. Faculty members in H Center has their own single-room offices surrounding H office.

Measurement Instruments

In this research，the measurement of noise effects mainly includes two components: the objective measurement of noise and the objective assessment of the noise.

In the noise mearing part, the measurement instrument was Sound Level Meter AR824, which can be used to measure the sound level between range of 30dB and 130dB.

In the noise assessing part, the measurement instrument was a questionnaire, which includes completion, choice question and open-ended question. The contents of the questionnaire included basic information of respondents, annoyance and distraction of noise, coping strategies, and opinions and suggestions for open-plan offices. The questionnaire contained 22 questions and takes about 5 minutes to complete.

(a)	(b)	(c)	(d)
Figure 2. Main desk types in S Office.

Data Collection

Data collection of this research was divided into two parts: the collection of sound data and the collection of questionnaires.

Sound data. We carried out twice data collections, in the evening with silent environment and in the morning of typical working day respectively. We chose 4 locations, which can be divided into 2 group with similar division type of desk and different clapboard material at adjacent location (see Figure 3).

In the evening, we used Sound Level Meter to measure the environmental sound level at 4 locations every 30 seconds. Around the 4 measuring locations, we repeatedly simulated the sound of opening and closing door, knocking on the keyboard and then measured the sound level respectively.

In the morning of typical working day, we used Sound Level Meter to measure the sound like what we do in the evening. Besides, we waited at each measuring point, and then, when people chatted with others or talked on the phone, we measured the sound level and made a record.

Questionnaire. For survey data, we spent a week for questionnaire issued and recycling. Our questionnaire was anonymous and asked to be returned to a location after completed. To recruit more participates, questionnaire was issued at work time, lunch break, evening after work, the weekend. After the week, a total of 18 questionnaires were issued and 17 were collected (see Figure 4)

Group 1 Point A with soft material & Point B with hard material	Group 2 Point C with soft material & Point D with hard material
Figure 3. Locations of measuring point.

Data Analysis

In this research, Mean Value method was used to describe and analyze the sound environment measured in S Office. For the noise assessment obtained through questionnaire, we adopt Mean Value method, t-test and Pearson Correlation Analysis by using EXCEL and SPSS 20.

Results

The Objective Measurement on Noise

As shown in Table.1, the mean environment sound level of 4 locations was 42.17dB(A) in the evening and 42.74dB(A) in the morning, which met the acoustical requirement of open-plan office. The noise of door open and close made a higher noise both in the evening and morning with the sound level of 56.67 dB(A) and 51.76 dB(A). The noise of knocking keyboard had a little impact on overall acoustical environment. The noise of chatting and phone call had the similar sound level that both higher than 48dB(A).

Table 1. The Sound Level of the Point A, B, C, and D.

Figure 5. The sound level comparison of the point A, B, C, and D.

[CHART]We measured the sound level in a continuous hour in the morning. We found that the frequency of opening or closing doors and knocking on the keyboard was less than the frequency of chatting and phone call. As shown in Figure 6, the noise level caused by people chatting and talking on the phone was continued higher during 9:42 to 10:42, which touched the upper limit of acceptable noise level at open-plan office. In this hour, there were only two periods of time that was relatively quiet, but each period of time was less than 10 minutes.

Figure 6. The noise level of chatting and phone call in an hour.

From the basic information part or questionnaire, we recognized that most of people using the open-plan office are Ph.D. students (see Figure 7). People come to S Office evenly during weekday and seldom come at weekend (see Figure 8). They often stay at office in the morning, at noon and in the afternoon, a few people work here in the evening and precious few people appear in the midnight (see Figure 9). What they do most frequently is reading and writing, other activities such as doing creative work and meeting will also carried out (Figure 10). Except one researcher using desk of type (b) and 3 researchers using desk of type (c), the rest of people all use desk of type (d), which have 3 pieces of clapboard with soft material (see Figure 2).

	[CHART]
Figure 7. Basic structure of researcher at S Office	Figure 8. Days that usually come to S Office
[CHART]	[CHART]
Figure 9. Time range that usually stay at S Office	Figure 10. Type of work usually do at S Office

The Objective Assessment on Noise, Noise effects and Privacy

Using method of Descriptive Statistic (using 1-7 Likert scale: 1 means strongly disagree with the space is noisy, 7 stands for strongly agree the space is noisy), results showed the mean score for level of noise, noise effects and privacy were close to neutral. The mean score for perceived level of noise was 4, with a standard deviation of 1.62, meaning on average participates feel neutral about the noise in the office. The mean score for level of annoyance was 4, with a standard deviation of 1.862. The mean score for level of distraction was 3.88, slightly lower than noisy and annoyance, with a standard deviation of 1.996. The mean score for level of privacy was 4.29, with a standard deviation of 1.795，obeying well with normal distribution.

H1：the Correlations Between Perceived Privacy and Perceived Noise

Hypothesis 1 was not strongly supported by the results. As shown in Table 2, applying Pearson Correlation analysis, there was weak correlation between privacy and perceived noise, distraction, and annoyance. However, there was a strong correlation between level of perceived distraction and perceived annoyance, implying that annoyance and distraction would happen at the same time. Also, there was a potential correlation between noisy and feeling of annoyance.

H2: The Correlations Between Coping Strategies and Noise effects

Hypothesis 2 was almost supported by the results. The results proof strong relationship between controls of noise and perceived noisy, perceived distraction from noise, and perceived annoyance noise.

H3：Correlation Between Types of work and Noise Effects.

Hypothesis 3 was strongly supported by the results. Applying Paired Samples Test, there was significant difference of annoyance when meeting compared with average perceived annoyance，t(14)=2.246, p＜0.05. Compared with average perceived distraction, perceived noise effects when meeting was significantly lower, t(15)=2.262, p＜0.05, as well as when entertaining, t(11)=3.093, p＜0.05.

Perceived noise effects for different types of noise

Annoyance. As shown in Figure 11, Conversations were the main contributor to annoyance. On average, the mean score for perceived annoyance was 4.00. The mean score for conversation annoyance was 3.86. Phone call and traffic noises were much lower than conversation, while keyboard noise and mechanical noise being the lowest.

[CHART]

Figure 11. Comparison of average score on annoyance of different types of noises.

[CHART]

Figure 12. Comparison of average score on annoyance of different types of conversations.

Concerning the type of conversation, the distraction by conversation between staffs was significantly higher than other types, and higher than the average score of distraction (see Figure 14).

[CHART]

Figure 13. Comparison of average score on distraction of different types of noises.

[CHART]

Figure 14. Comparison of average score on distraction of different types of conversations.

Majority of the participators used certain coping strategies. As shown in Figure 15, 71% percent of them used normal headphones, 29% of them used noise-cancelling headphone. It was worth to mention that 41% of them chose avoid working in the office as a coping strategy, which could partially explain why the vacancy rate was high in the office. Also, 29% percent of participators chose avoid working in the office time on weekday, when conversations frequently happen. No participators chose asking others to lower their voice. [CHART]

Preference and opinions on open-plan office. In the answer for open-end questions, 59% of participators preferred open-plan office better than single rooms, saying, “It’s great of building the sense of learning community, easy for collaboration. Noise is not really avoidable” or “It encourages unplanned discussion and access to advisor”.

However, there were also opposite opinions, saying, “Not helpful for communication and collaboration”. And some of the participators want an in-between options like shared office or more partitions, such as “single or smaller open-plan office” “smaller shared office rooms, shared amongst 2-4 grad students”, “open-plan office with cube and partitions”.

76% of the participators thought their work performance were significantly higher in the evening or on weekend, concerning that “Reading scholarly materials, academic writings do require quiet environment”.

Discussion

Overall, the noise level in the office was barely acceptable, with background noise 42~43dB. However, the constant noise from phone call and conversation during typical weekday keep the noise level almost at 49~50dB, hitting the highest acceptable line for workplace. Also, 73% of the participators were Ph. D student, and their main types of work was reading and writing. These types of work were significantly influenced by the noise compared to other types of work. The noise effects of conversations between staffs was higher than other types of noise. And noticeably, 76% of the participator thought their work performance was higher in quiet time, when conversation rarely happens.

In terms of control, the control of noise, annoyance and distraction has potential relationship with the subjective noise perception. This implies if we can offer more strategies for students to cope with the noise, the noise effects could also be controlled.

Conclusions

The present study explored the correlations between subjective noise experience (distraction and annoyance) of researchers in open-plan office and their spatial privacy, coping strategies, and types of work. Through sound level measurement and questionnaire collection, three hypotheses were tested.

The correlation between spatial privacy and subjective noise experience was not supported by the data. Coping strategies was proved to have strong relationship with perceived annoyance and distraction of noise. When doing different types of work, subjective noise experience showed significant differences. Meeting and entertaining showed less annoyed or distracted by same level of noise. Together with other information generated from this study, when reading and writing, participators felt more annoyed or distracted by the noise (mainly conversations and phone calls), leading to low performance and high vacancy in the office during daytime.

Taking the result that 59% of the participators prefer open-plan office for communication and collaboration, lowering the impact of noise from conversations and phone calls could be considered in the future remodeling of the office.

The suggestions from the participators in open-end questions’ answer for remodeling the office could be divided into 4 categories:

1 Partition, such as “partition walls with opaque walls and transparent transoms” and “individual seating area with wall or bookshelves”.

2 Separate spaces for meeting, such as “more meeting rooms” and “Separate meeting area”.

3 Signage and Regulation, such as “using single bar ‘quiet area’ and “set up quiet study hours (e.g.8-12 am, 1-5 pm)”.

4 Noise control utilities, such as “Better acoustic treatment” and “give everyone a headphone”.

The above suggestions could also be regarded as more options to control noise effects. What’s more, enclosed area for staff to work will also help control the noise effects and benefit the entire sound environment.

Limitations

The number of participants in the study was insufficient due to the number constraints of staff in the office. The composition and arrangement of staff in the office are relatively loose, and there is no strict control over staff entry or exit and some emergencies, which may have an impact on the experimental results. In the future, open-plan offices with multiple modes and acoustic conditions could be selected for comparative research, and also, larger numbers of participants could be investigated to improve the research accuracy.

Acknowledgments

The authors deeply appreciate the support of the users in the study site, who made this report possible, and the valuable input provided by Dr. Zhipeng Lu.

References

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