| 1. |
- Bengtsson, Johanna, 1974, et al.
(författare)
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Evaluations of effects due to low-frequency noise in a low demanding work situation
- 2004
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 278:1-2, s. 83-99
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Tidskriftsartikel (refereegranskat)abstract
- Noise sources with a dominating content of low frequencies (20-200 Hz) are found in many occupational environments. This study aimed to evaluate effects of moderate levels of low-frequency noise on attention, tiredness and motivation in a low demanding work situation. Two ventilation noises at the same A-weighted sound pressure level of 45 dB were used: one of a low-frequency character and one of a flat frequency character (reference noise). Thirty-eight female subjects worked with six performance tasks for 4 h in the noises in a between-subject design. Most of the tasks were monotonous and routine in character. Subjective reports were collected using questionnaires and cortisol levels were measured in saliva. The major finding in this study was that low-frequency noise negatively influenced performance on two tasks sensitive to reduced attention and on a proof-reading task. Performances of tasks aimed at evaluating motivation were not significantly affected. The difference in work performance was not reflected by the subjective reports. No effect of noise was found on subjective stress or cortisol levels.
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| 2. |
- Bengtsson, Johanna, 1974, et al.
(författare)
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Sound characteristics in low frequency noise and their relevance for the perception of pleasantness
- 2004
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Ingår i: Acta Acoustica. ; 90:1, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- Noise sources with a dominant content of low frequencies (20-200 Hz) are found in many occupational environments. Work efficiency has been found in two earlier studies to be impaired to a larger degree when working in a low frequency ventilation noise than when working in a flat frequency ventilation noise at the same A-weighted sound pressure level. Other previous studies indicate that different sound characteristics found in low frequency noise are important for the way in which low frequency noise affects humans, and better knowledge of these characteristics could lead to better methods for assessing low frequency noise in occupational environments. The aim of this study was to evaluate the influence of frequency balance between low and high frequencies, which affects the slope of the frequency spectra, and the modulation frequency on subjects´ perception of a pleasant low frequency noise. The results showed that the subjects preferred either a higher or a lower modulation frequency as compared to that of the original low frequency noise, both choices leading to less perceivable modulations. Furthermore, the subjects preferred a lower relative content of frequencies below 500 Hz, but only as long as the original low frequency noise contained modulations and the variations were made within a constant A-weighted sound pressure level. The results are discussed in relation to improved guidelines and to the previously suggested theory of slope of the frequency spectra and problems involved with the implementation of that theory.
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| 3. |
- Byström, Pernilla, 1976, et al.
(författare)
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Appraised psychological workload, musculoskeletal symptoms, and the mediating effect of fatigue: A structural equation modeling approach.
- 2004
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Ingår i: Scandinavian Journal of Psychology. - : Wiley. ; 45:4, s. 331-341
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to test two structural models of the relationship between appraised psychologicla workload and musculoskeletal symptoms from the neck, shoulder, and upper and lower back with different aspects of perceived fatigue as mediating variables. In this cross-sectional study a questionnaire survey was conducted among employees at three Swedish assembly plants (n=305). The proposed models were tested for one general fatigue dimension - lack of energy - and four specific fatigue dimensions - physical discomfort, physical exertion, lack of motivation, and sleepiness - using structural equation modeling. The results indicate that the role of perceived fatigue in the relationship between appraised workload and musculoskeletal symptoms is different for different aspects of fatigue. The general fatigue dimension, lack of energy, does not mediate the relationship. As regards the specific fatigue dimensions, the relationship is partially mediated by physical discomfort and lack of motivation but not by physical exertion or sleepiness. Appraised psychological workload has a unique effect on musculoskeletal symptoms not mediated by fatigue.
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| 4. |
- Haglund, Björn, 1962
(författare)
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Stimulated recall: Några anteckningar om en metod att generera data
- 2003
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Ingår i: Pedagogisk Forskning i Sverige. - 1401-6788 .- 2001-3345. ; 8:3, s. 145-157
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Tidskriftsartikel (refereegranskat)abstract
- Sammanfattning: I artikeln beskrivs stimulated recall, en metod där man med hjälp av ljudband- eller videoinspelat material dokumenterar en intervjupersons verksamhet. Den intervjuade får kort efter inspelningen ta del av materialet för att se och höra sig själv i aktion och kommentera inspelningen. På så sätt ska det inspelade materialet stimulera och påminna respondenten om sitt tänkande under den dokumenterade episoden. Det är svårt att se stimulated recall som en metod med en bestämd manual, som man ska följa. Det är snarare så att undersökningar som genomförts med stimulated recall kan skilja sig åt på betydelsefulla sätt, bland annat beroende på forskningsintresse, intervjutekniker men även beroende på mer grundläggande antaganden om vad respondenterna egentligen har möjlighet att verbalisera.
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