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. (C) 2004 Elsevier Ltd. All rights reserved.

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.

Background: More knowledge is needed ofoccupational attainment of persons with disabilities, i.e. the relationship between their educational level and their profession, and factors of importance for this relationship.

Objective: To compare occupational attainment among persons with and without a disability.

Method: 3 396 informants with disabilities and 19 004 non-disabled informants participated (control group) in a survey study by Statistics Sweden.The informants with disabilities were divided into six groups.

Results: Occupational attainment did not differ between the disability groups, neither between persons with and without a disability. Follow-up analysis showed that men with disabilities with primary or secondary school had an occupation above their educational level to a significantlylarger extent than women with disabilities. This pattern was even clearer in comparison with the control group. Persons without disabilities, with secondary or higher education, were more successful in the labor market than persons with disabilities. Occupational attainment increased with age in both groups.

Conclusions: Young women with disabilities who only have primary or secondary education run a higher risk of having a job that is below their educational level than men at the same educational level. This indicates discriminating mechanisms in the society related to gender and ability.

The employment status of groups with different disabilities wasanalysed as were potentially important moderating factors (workability, structural and individual factors). A secondary analy-sis was performed on 4359 respondents with disabilities fromStatistics Sweden's Labour Market Investigation. The respondentswere divided into six disability groups (communicative-hearing,communicative-speech-reading, communicative-vision, psycho-logical disability, medical disability, physical disability). Logisticregression analyses showed that the probability of being employedwas highest among respondents with hearing disabilities andrespondents with psychological disabilities were least likely tobe employed. Being a woman (very young or old) with onlyprimary education and with partially or very impaired workability, reduced employment opportunities. Higher education didnot increase employment opportunities for respondents withimpaired work ability. In summary, the type of disability is essentialfor employment opportunities, and differences between disabil-ity groups cannot be explained by differences in other variables. 

This study aimed to examine support and adaptation needed by persons with four different types of disabilities, either at their workplace or in order to enter the labour market. A secondary analysis was conducted, based on the regular labour market survey (AKU), and an additional survey which included questions specifically posed to persons with disabilities. All participants had either partly or very reduced work ability. There was more need for adaptation than for support, independently of work ability and current employment status. Around 60% of respondents with a psychological disability reported a need for adapted work pace and working time, both at their workplace and in order to enter the labour market. Adapted work tasks were an important factor, especially for persons who were not currently working; around half of the non-employed participants said this adaptation could make it possible for them to work, regardless of type of disability.

The aim of the present study was to test two structural models of the relationship between appraised psychological 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.

Changeability of work values was studied by longitudinal analyses of nurses and engineers from the Stockholm area in Sweden. Questionnaires were completed by 173 male and 48 female engineers and 353 female and 31 male nurses at three measurement occasions covering about four and half years from the end of their vocational education. Women's ratings of Social relations and Altruism remained higher than men's while women & acute; ratings of Benefit/career and Influence increased which eliminated the initial gender difference. The changeability of work values is discussed in terms of challenges and norms in working life.

Gender related changes of work values were analyzed in a longitudinal questionnaire study of 173 male and 48 female engineers and 353 female and 31 male nurses at three measurement occasions covering about four and half years from the end of their vocational education. At all occasions, Social relations were rated as more important by women than by men and Altruism was given higher ratings by the nurses than by the engineers. Within both occupations women’s mean Altruism ratings were higher than men’s mean ratings, and in all groups except male engineers the mean ratings dropped between the three occasions. Women’s ratings of Benefits and career and Influence were strengthened in both occupations, thereby eliminating an initial gender difference. The stability of work values is discussed in terms of challenges and norms in working life.

Some conditions that people would not ordinarily appraise as demanding may constrain restoration when experienced in places sought out for restoration. The constraint of restoration by community noise exemplifies this phenomenon. Community noise regulations assume a moderating effect of context on noise annoyance, in that they impose stricter controls on sound levels in locations and at times normally dedicated to restoration. To further explore the constrained restoration phenomenon, in this paper we review research on reactions to human-produced sounds in natural settings, like parks, which many people particularly value for restoration. We also consider ambient sound qualities that promote restoration

Free recall of spoken words in Swedish (native tongue) and English were assessed in two signal-to-noise ratio (SNR) conditions (+3 and +12 dB), with and without half of the heard words being repeated back orally directly after presentation [shadowing, speech intelligibility (SI)]. A total of 24 word lists with 12 words each were presented in English and in Swedish to Swedish speaking college students. Pre-experimental measures of working memory capacity (operation span, OSPAN) were taken. A basic hypothesis was that the recall of the words would be impaired when the encoding of the words required more processing resources, thereby depleting working memory resources. This would be the case when the SNR was low or when the language was English. A low SNR was also expected to impair SI, but we wanted to compare the sizes of the SNR-effects on SI and recall. A low score on working memory capacity was expected to further add to the negative effects of SNR and language on both SI and recall. The results indicated that SNR had strong effects on both SI and recall, but also that the effect size was larger for recall than for SI. Language had a main effect on recall, but not on SI. The shadowing procedure had different effects on recall of the early and late parts of the word lists. Working memory capacity was unimportant for the effect on SI and recall. Thus, recall appear to be a more sensitive indicator than SI for the acoustics of learning, which has implications for building codes and recommendations concerning classrooms and other workplaces, where both hearing and learning is important.

An experiment will be reported which assessed speech intelligibility and free recall of spoken words in Swedish (native tongue) and in English heard under different signal-to-noise (S/N) ratios (+3 and +12 dB), and with/without the spoken words being repeated back orally directly after presentation (shadowing). All participants encountered all experimental conditions. Twelve wordlists with 12 words each were generated in English as well as in Swedish. The words were chosen according to their ranks in category norms for the two languages, and no category was the same for the two languages. Blocks of counter balanced presentation orders, S/N-ratios and shadowing/no shadowing were generated. After each wordlist the participants wrote down the words they could recall. Pre-experimental measures of working memory capacity were taken. The basic hypotheses for the recall of the words were that working memory would be overloaded when the S/N-ratio was low, there was no shadowing and when the language was English. A low score on working memory capacity was expected to further enhance these effects. While writing this abstract data collection is still in progress but results will be presented at the conference.

The aim of this study was to investigate if nursing students improved their work technique when assisting a simulated patient from bed to wheelchair after proficiency training, and to investigate whether there was a correlation between the nursing students' work technique and the simulated patients' perceptions of the transfer. METHOD: 71 students participated in the study, 35 in the intervention group and 36 in the comparison group. The students assisted a simulated patient to move from a bed to a wheelchair. In the intervention group the students made one transfer before and one after training, and in the comparison group they made two transfers before training. Six variables were evaluated: work technique score; nursing students' ratings of comfort, work technique and exertion, and the simulated patients' perceptions of comfort and safety during the transfer. The result showed that nursing students improved their work technique, and that there was a correlation between the work technique and the simulated patients' subjective ratings of the transfer. In conclusion, nursing students improved their work technique after training in patient transfer methods, and the work technique affected the simulated patients' perceptions of the transfer.

The aim of this project was to develop a direct observation instrument to assess the work technique of nursing personnel during patient transfers and to test the validity and reliability of the instrument. An expert group developed this instrument, called DINO (Direct Nurse Observation instrument for assessment of work technique during patient transfers), which contains 16 items divided into three phases of a transfer: the preparation, performance and result phases. To quantify the assessments a scoring system was constructed, giving an overall score for each transfer, depending on the level of musculoskeletal health and safety. Four observers assessed 45 patient transfers at hospital wards and showed in an evaluation that the inter-observer reliability and criterion-related validity of DINO was satisfactory. The assessments with the DINO instrument are done directly when the transfer occurs, without costly equipment. Therefore, it has a wide range of applications. For example, when evaluating training in work technique or when identifying an unsafe work technique as a risk factor for musculoskeletal problems in epidemiological studies. (C) 2004 Elsevier Ltd. All rights reserved.

An evaluation of the impact of partial automation strategies on productivity and ergonomics at an electronics company was performed. This change included adoption of a serial line flow from a parallel batch flow strategy. The change process, which used both a project head group and a work organisation group, was also studied. The partial automation of assembly operations reduced the total repetitive assembly work at the system level and increased productivity. At the remaining assembly stations however, the repetitive assembly work increased due to the automation of the transportation functions and increased work-pace. The operators found the mental work load was higher in the new system. They also experienced the manual assembly station in the beginning of the line as the worst job in the system . Lack of management continuity at the department was identified as one of the largest process problems. The manager set his view on how the production and work environment goals should be met. Thus the manager set the work organisation without adopting the plan of work rotation that the work organisation group had presented. This contributed to dissatisfaction amongst the operators involved in the development process.

The paper presents a theoretical analysis of possible effects of reverberation time on the cognitive load in speech communication. Speech comprehension requires not only phonological processing of the spoken words. Simultaneously, this information must be further processed and stored. All this processing takes place in the working memory, which has a limited processing capacity. The more resources that are allocated to word identification, the fewer resources are therefore left for the further processing and storing of the information. Reverberation conditions that allow the identification of almost all words may therefore still interfere with speech comprehension and memory storing. These problems are likely to be especially serious in situations where speech has to be followed continuously for a long time. An unfavorable reverberation time (RT) then could contribute to the development of cognitive fatigue, which means that working memory resources are gradually reduced. RT may also affect the cognitive load in two other ways: RT may change the distracting effects of a sound and a person's mood. Both effects could influence the cognitive load of a listener. It is argued that we need studies of RT effects in realistic long-lasting listening situations to better understand the effect of RT on speech communication. Furthermore, the effect of RT on distraction and mood need to be better understood.

Sedan länge har det hävdats att om man gillar musiken löper man inte risk att skadas av den. För detta finns inget stöd, men däremot finns visst stöd för att ljud som upplevs som obehagliga leder till större temporär hörselnedsättning än emotionellt neutrala eller positiva ljud. Att man tycker att ett ljud är obehagligt skulle alltså möjligen kunna öka risken för hörselpåverkan. Detta skulle i så fall kunna vara en effekt av att den fysiologiska stressreaktionen ökar känsligheten hos hörselorganet.

Många aspekter av musikers arbetsförhållanden kan bidra till att göra arbetet stressande, men arbetsvillkoren skiljer sig mycket mellan olika musikergrupper.

Inga studier har påvisat att risken för permanent hörselnedsättning påverkas av attityd till ljudet eller av stress.

Samband har påvisats mellan psykiatriska symptom och förekomsten av tinnitus och besvärens styrka, och besvären är ofta mest påträngande i stresstillstånd. Inga studier har dock kunnat påvisa att psykologiska förhållanden har betydelse för uppkomsten av tinnitus. Hörselnedsättning, tinnitus och andra hörselskador kan få särskilt dramatiska konsekvenser för musiker och de upplevs därför också som ett särskilt stort hot av denna grupp.

Speech communication under unfavourable acoustic conditions means that a larger part of the limited working memory resources must be allocated to the phonological coding of the speech. Less resources therefore remain for the further processing of speech: integration of current information with previously presented parts of the speech and with permanently stored information and the more permanent storing of new information. Effects of reverberation time on the listener’s cognitive load and learning are discussed from this perspective. Studies are needed of reverberation effects in realistic long-lasting speech communication situations to better understand the effect of RT on speech communication.

Research on the cognitive processing of speech indicates that the probability of correct identification of words is an insufficient indicator of how reverberation time (RT) affects speech communication. Speech communication under unfavourable reverberation conditions means that a larger part of the limited working memory resources must be allocated to the phonological coding of the speech. Less resources therefore remain for the further processing of speech: integration of current information with previously presented parts of the speech and with permanently stored information and the more permanent storing of new information. Even if reverberation conditions allow the identification of almost all words they may therefore have the effect that the spoken message is less well understood and remembered. Effects of the RT on the listener’s cognitive load, fatigue and learning are discussed from this perspective. It is argued that we need studies of reverberation effects in realistic long-lasting speech communication situations to better understand the effect of RT on speech communication.

Dåliga lyssningsförhållanden innebär att en stor del av den tillgängliga kognitiva kapaciteten måste användas för att höra vad som sägs, och att en mindre del därför skulle kunna användas för att tolka och lagra informationen. Detta borde gälla även då lyssningsförhållandena inte är sämre än att allt som sägs kan uppfattas med en viss ansträngning. Detta har prövats i en en serie försök vars resultat stöder denna hypotes. Resultaten tyder också på att effekten blir större ju sämre arbetsminneskapacitet man har.

The aim of the study was to explore if recall of words and recognition of sentences orally presented was affected by a background noise. A further aim was to investigate the role of working memory capacity in performance in these conditions. Thirty-two subjects performed a word recall and a sentence recognition test. They repeated each word to ensure that they had heard them. A reading span test measured their working memory capacity. Performance on the word recall task was impaired by the background noise. A high reading span score was associated with a smaller noise effect, especially on recall of the last part of the word list.

Experimentet är den vetenskapliga metod som ger oss de bästa möjligheterna att ta reda på orsakerna bakom det vi vill studera. Alla vetenskapliga undersökningar har svagheter, så även de som är baserade på experiment. Skillnaden är att experimentet erbjuder unika möjligheter att komma runt svårigheterna. Det är om detta Experimentell metodik för beteendevetare handlar. Även de studenter och forskare som själva aldrig kommer att genomföra ett experiment behöver god kännedom om experimentell metodik.

The aim of this study was to identify risk indicators for high stress and low mental energy as well as to describe psychosocial working conditions at different types of call centres.

A cross sectional questionnaire study was conducted among 1183 operators from 28 call centres, in Sweden both external and internal, with different levels of task complexity, ownership and geographical location.

The stress level was moderately high and the energy level fairly high. Stress levels tended to be lower and psychosocial conditions better with increasing level of task complexity. Fourteen per cent of the operators were in a state of high stress/low energy (“worn out”) and 47% in high stress/high energy (“committed under pressure”). Operators in a state of low stress/high energy (“committed without pressure”) were most likely to report a better health status. High stress and lack of energy was mainly associated with time pressure, low decision latitude, and lack of social and supervisor support.

Time pressure in combination with lack of support and influence should be seen as a potential high risk situation for the development of a “worn-out” state among call centre operators. Management should make use of this knowledge in order to promote a long lasting efficient and healthy call centre work.

This cross-sectional study of a group of assembly workers (n=289) tested the hypothesis that affective stress responses mediate the effect of psychosocial work conditions on musculoskeletal complaints (MSCs). Self-reported work demands, control, social support, stress, energy, and MSCs were analysed in hierarchical logistic regression analyses. High work demands were related to a higher risk of shoulder problems. Work demands and social support, but not control, were related to stress; and more musculoskeletal complaints were found in the group with high stress than in the low-stress group. The analyses supported the hypothesis that the effects of work demands on shoulder problems were mediated by the affective stress response, whereas this did not seem to be the case for the effect of social support and control conditions on neck problems. A weaker relation to psychosocial work conditions was shown for back problems than for shoulder and neck problems. Relevance to industry: Psychosocial work conditions have repeatedly been shown to be related to risk of musculoskeletal complaints. Individual subjective stress responses may help to identify those who are at risk with respect to shoulder complaints.

The aim of the study was to explore if a long reverberation time has the same effect on recall of spoken words as background noise was shown to have in a previous study. A further aim was to study the influence of working memory capacity on performance in these conditions. Thirty-two subjects performed a word recall and a sentence recognition test. They repeated each word to ensure correct identification. A reading span test measured their working memory capacity. Performance of the word recall task was impaired by the long reverberation time. The effect was most evident in the primacy part of the word list. No correlation was found between reading span score and recall performance.

The aim of the study was to explore if a long reverberation has the same effect on recall of spoken words as background noise was shown to have in a previous study. A further aim was to study the role of working memory capacity for performance in these conditions. Thirty-two subjects performed a word recall and a sentence recog-nition test. They repeated each word to ensure correct identification. A reading span test measured their working memory capacity. Performance of the word recall task was impaired by the long reverberation time. The effect was most evident in the pri-macy part of the word list. The reading span score was unrelated to recall perform-ance.

When spoken information is presented in unfavourable listening conditions a larger part of the available and limited information processing resources must be allocated to the identification of the words spoken. This leaves fewer resources for the further processing of the speech (the interpretation and storing of the information). In such circumstances understanding and memory of speech might be impaired although each word has been correctly heard. This hypothesis was confirmed in two previous studies where memory of a word list was shown to be impaired when presented in unfavourable listening conditions: unfavourable signal/noise ratio (Kjellberg, Ljung & Hallman, 2008) and a too long reverberation time (Ljung & Kjellberg, in press). Kjellberg et al. also found that the noise effect was weaker the better the working memory capacity (as measured with a reading span task).

This paper reports two experiments on the effects of degraded speech signals on memory for spoken lectures. Experiment 1 showed that broadband noise impairs university students’ memory for a spoken lecture, even though the participants heard what was said. Experiment 2 showed that reverberation has detrimental effects to school adolescents’ memory for spoken lectures, similar to broadband noise. The results suggest that poor listening conditions (resulting from background noise and/or long reverberation time) impair memory and learning, even if the conditions allow the listeners to hear what is said. Since the goal for students and pupils attending to lectures is to remember the lecture rather than just hearing what is said, the results presented here indicate that standards for acceptable signal-to-noise ratios and reverberation times in buildings designed for learning should consider the distinction between speech intelligibility and memory. Standards should be based on memory criteria instead of intelligibility criteria.