The effect of low ventilation rate with elevated bioeffluent concentration on work performance, perceived indoor air quality, and health symptoms.

The aim of this laboratory experiment was to study the effects of ventilation rate, and related changes in air quality, predominantly bioeffluents, on work performance, perceived indoor air quality, and health symptoms in a typical conditions of modern open-plan office with low material and equipment emissions. In Condition A, outdoor air flow rate of 28.2 l/s person (CO2 level 540 ppm) was applied and in Condition B, outdoor air flow rate was 2.3 l/s person (CO2 level 2260 ppm). CO2 concentration level was used as an indicator of bioeffluents. Performance was measured with seven different tasks which measure different cognitive processes. Thirty-six subjects participated in the experiment. The exposure time was 4 hours. Condition B had a weak negative effect on performance only in the information retrieval tasks. Condition B increased slightly subjective workload and perceived fatigue. No effects on health symptoms were found. The intensity of symptoms was low in both conditions. The experimental condition had an effect on perceived air quality and observed odor intensity only in the beginning of the session. Although the room temperature was controlled in both conditions, the heat was perceived to impair the performance more in Condition B.

The effect of slightly warm temperature on work performance and comfort in open-plan offices - a laboratory study.

The aim of the study was to determine the effect of a temperature of 29°C on performance in tasks involving different cognitive demands and to assess the effect on perceived performance, subjective workload, thermal comfort, perceived working conditions, cognitive fatigue, and somatic symptoms in a laboratory with realistic office environment. A comparison was made with a temperature of 23°C. Performance was measured on the basis of six different tasks that reflect different stages of cognitive performance. Thirty-three students participated in the experiment. The exposure time was 3.5 h in both thermal conditions. Performance was negatively affected by slightly warm temperature in the N-back working memory task. Temperature had no effect on performance in other tasks focusing on psychomotor, working memory, attention, or long-term memory capabilities. Temperature had no effect on perceived performance. However, slightly warm temperature caused concentration difficulties. Throat symptoms were found to increase over time at 29°C, but no temporal change was seen at 23°C. No effect of temperature on other symptoms was found. As expected, the differences in thermal comfort were significant. Women perceived a temperature of 23°C colder than men.

Effects of acoustic environment on work in private office rooms and open-plan offices - longitudinal study during relocation.

The aim was to determine how the perceived work environment, especially acoustic environment, and its effects differed in private office rooms and in open-plan offices. The subjects consisted of 31 workers who moved from private office rooms to open-plan offices and who answered the questionnaire before and after the relocation. Private office rooms were occupied only by one person while open-plan offices were occupied by more than 20 persons. Room acoustical descriptors showed a significant reduction in speech privacy after relocation. The noise level averaged over the whole work day did not change but the variability of noise level reduced significantly. Negative effects of acoustic environment increased significantly, including increased distraction, reduced privacy, increased concentration difficulties and increased use of coping strategies. Self-rated loss of work performance because of noise doubled. Cognitively demanding work and phone conversations were most distracted by noise. The benefits that are often associated with open-plan offices did not appear: cooperation became less pleasant and direct and information flow did not change. Nowadays, most office workers, independent of job type, are located in open-plan offices without the individual needs of privacy, concentration and interaction being analysed. This intervention study consisted of professional workers. Their work tasks mainly required individual efforts, and interaction between other workers was not of primary concern, although necessary. The results suggest that the open-plan office is not recommended for professional workers. Similar intervention studies should also be made for other job types.

Performance effects and subjective disturbance of speech in acoustically different office types--a laboratory experiment.

UNLABELLED: This study examined how the intelligibility of irrelevant speech, determined with the Speech Transmission Index (STI), affects demanding cognitive task performance. Experiment was carried out in a laboratory that resembled an open-plan office. Three speech conditions were tested corresponding to a private office (STI = 0.10), an acoustically excellent open office (STI = 0.35) and an acoustically poor open office (STI = 0.65). All conditions were presented at equal level, 48 dBA. The STI was adjusted by the relative levels of speech and masking sound. Thirty-seven students participated in the experiment that lasted for 4 h. All participants performed five tasks in each of the three speech conditions. Questionnaires were used to assess subjective perceptions of the speech conditions. Performance in the operation span task, the serial recall and the activation of prior knowledge from long-term memory were deteriorated in the speech condition with the highest speech intelligibility (STI = 0.65) in comparison with the other two conditions (STI = 0.10 and STI = 0.35). Unlike performance measures, questionnaire results showed consistent differences among all three speech conditions, i.e. subjective disturbance increased with ascending speech intelligibility. Thus, subjective comfort was disturbed more easily than performance. The results support the use of STI as an essential room acoustic design measure in open-plan offices. PRACTICAL IMPLICATIONS: Reduction of speech intelligibility in office environments by proper acoustic design would be beneficial in terms of both work performance and subjective comfort. Proper acoustic design requires both the use of high acoustic absorption and an appropriate masking sound.

The effect of speech and speech intelligibility on task performance.

The aim of this study was to find out what are the effects of three different sound environments on performance of cognitive tasks of varying complexity. These three sound environments were 'speech', 'masked speech' and 'continuous noise'. They corresponded to poor, acceptable and perfect acoustical privacy in an open-plan office, respectively. The speech transmission indices were 0.00, 0.30 and 0.80, respectively. Sounds environments were presented at 48 dBA. The laboratory experiment on 36 subjects lasted for 4 h for each subject. Proofreading performance deteriorated in the 'speech' (p < 0.05) compared to the other two sound environments. Reading comprehension and computer-based tasks (simple and complex reaction time, subtraction, proposition, Stroop and vigilance) remained unaffected. Subjects assessed the 'speech' as the most disturbing, most disadvantageous and least pleasant environment (p < 0.01). 'Continuous noise' annoyed the least. Subjective arousal was highest in 'masked speech' and lowest in 'continuous noise' (p < 0.05). Performance in real open-plan offices could be improved by reducing speech intelligibility, e.g. by attenuating speech level and using an appropriate masking environment.

A model predicting the effect of speech of varying intelligibility on work performance.

UNLABELLED: Speech is the most distracting sound in (open-plan) offices. Several laboratory studies have shown that speech impairs the performance of, for example, reading and short-term memory. It is not the sound level of speech that determines its distracting power but its intelligibility, which can be physically determined by measuring the Speech Transmission Index (STI). The aim of this study was to develop a mathematical model that predicts how much the performance is reduced due to speech of varying intelligibility. The model was based on the literature according to which performance decrements have been 4-45% depending on the task. The best performance occurs when speech is absent (STI=0.0), and the strongest performance decrement occurs when speech is perfectly heard (STI=1.0). The shape of the performance vs. STI between 0.0 and 1.0 was adopted from the general speech intelligibility theory. The performance starts to decrease when STI exceeds 0.2. Highest performance decrease is reached already when STI exceeds 0.60. PRACTICAL IMPLICATIONS: The prediction model can be exploited in the evaluation of work performance in different acoustical conditions in open-plan offices when STI is known. It can be utilized to promote actions aiming at better acoustical conditions.

Enhancing maximum measurable sound reduction index using sound intensity method and strong receiving room absorption.

The sound intensity method is usually recommended instead of the pressure method in the presence of strong flanking transmission. Especially when small and/or heavy specimens are tested, the flanking often causes problems in laboratories practicing only the pressure method. The purpose of this study was to determine experimentally the difference between the maximum sound reduction indices obtained by the intensity method, RI,max, and by the pressure method, Rmax. In addition, the influence of adding room absorption to the receiving room was studied. The experiments were carried out in an ordinary two-room test laboratory. The exact value of RI,max was estimated by applying a fitting equation to the measured data points. The fitting equation involved the dependence of the pressure-intensity indicator on measured acoustical parameters. In an empty receiving room, the difference between RI,max and Rmax was 4-15 dB, depending on frequency. When the average reverberation time was reduced from 3.5 to 0.6 s, the values of RI,max increased by 2-10 dB compared to the results in the empty room. Thus, it is possible to measure wall structures having 9-22 dB better sound reduction index using the intensity method than with the pressure method. This facilitates the measurements of small and/or heavy specimens in the presence of flanking. Moreover, when new laboratories are designed, the intensity method is an alternative to the pressure method which presupposes expensive isolation structures between the rooms.

Dual roles for c-Jun N-terminal kinase in developmental and stress responses in cerebellar granule neurons.

c-Jun N-terminal kinases (JNKs) typically respond strongly to stress, are implicated in brain development, and are believed to mediate neuronal apoptosis. Surprisingly, however, JNK does not respond characteristically to stress in cultured cerebellar granule (CBG) neurons, a widely exploited CNS model for studies of death and development, despite the regulation of its substrate c-Jun. To understand this anomaly, we characterized JNK regulation in CBG neurons. We find that the specific activity of CBG JNK is elevated considerably above that from neuron-like cell lines (SH-SY5Y, PC12); however, similar elevated activities are found in brain extracts. This activity does not result from cellular stress because the stress-activated protein kinase p38 is not activated. We identify a minor stress-sensitive pool of JNK that translocates with mitogen-activated protein kinase kinase-4 (MKK4) into the nucleus. However, the major pool of total activity is cytoplasmic, residing largely in the neurites, suggesting a non-nuclear role for JNK in neurons. A third JNK pool is colocalized with MKK7 in the nucleus, and specific activities of both increase during neuritogenesis, nuclear JNK activity increasing 10-fold, whereas c-Jun expression and activity decrease. A role for JNK during differentiation is supported by modulation of neuritic architecture after expression of dominant inhibitory regulators of the JNK pathway. Channeling of JNK signaling away from c-Jun during differentiation is consistent with the presence in the nucleus of the JNK/MKK7 scaffold protein JNK-interacting protein, which inhibits JNK-c-Jun interaction. We propose a model in which distinct pools of JNK serve different functions, providing a basis for understanding multifunctional JNK signaling in differentiating neurons.