Martin Schütte

Mental strain and annoyance during cognitive performance in different traffic noise conditions

In built-up areas, an increasing number of persons are affected by road traffic noise while performing mental work. This experimental study focused on annoyance and mental strain due to various noise scenarios. A total of 102 healthy, young persons (51 women, 51 men, aged 18–31 years) were randomly assigned to one of five experimental conditions determined by traffic flow (even, lumped) and traffic composition (20%, 40% heavy vehicles). While exposed to noise they performed a grammatical reasoning and a mathematical processing task. Performance and mental strain were not affected by any of the five noisy conditions. Individuals with high noise sensitivity were partially more annoyed and performed less than persons with low sensitivity. Statement of Relevance: The present study provides information about mental strain due to tasks with different cognitive demands and the role of noise sensitivity in various traffic noise conditions. The results show that measures aiming at the reduction of the proportion of heavy vehicles should additionally consider particular traffic flow.

Case study: Investigation into the subjective strain at two differently designed automobile assembly workplaces

Abstract The present case study involved a stress-and-strain-related comparison between two different automobile assembly workplaces, one of which is distinguished by the ergonomic design principles it incorporates. The application of these principles has, above all, enabled a reduction in the proportion of activities to be performed in disadvantageous body postures. The strain was determined using the fatigue-monotony-satiation questionnaire (BMS), a methodology specially developed for the assessment of assembly and operating activities. The derived results demonstrate that the implemented design measures have led to a reduction in the overall level of strain. Relevance to industry The investigation provides indications of readily realizable design measures which allow, particularly, stress-and-strain-prone body postures adopted at automobile assembly workplaces to be avoided.

The reliability of the noise sensitivity questionnaire in a cross-national analysis.

Noise sensitivity is regarded as a relevant predictor for annoyance reactions. Since many studies have focused on noise sensitivity at an international level, the present analysis was conducted to detect national peculiarities concerning noise sensitivity. Using the approach of the generalizability theory, reliability of the noise sensitivity questionnaire was analyzed taking into consideration relevant facets assumed to contribute to the measurement error. A total of 126 individuals from seven European countries participated in this study. The reliability coefficients for the global noise sensitivity score ranged from 0.90 to 0.91. It was determined that the translated questionnaires are comparable.

Mental strain and the problem of repeated measurements

In the past, stress and strain arising from the execution of mentally demanding tasks have been measured by means of surveys. Such methods require repeated investigation of the individual perceptions and valuations during task fulfilment to record time-dependent changes in strain levels. However, it is possible that the individual measurement procedures employed in surveys--as artefacts--may cause a change in the stress situation and subsequently in the resulting mental strain. The results of the experiments carried out to investigate this hypothesis verify that repeated measurements have a similar effect as a short break. The repeated measurements taken during progressive studies are, therefore, likely to affect the conditions of stress. A change in the level of mental strain recorded can be expected, particularly if the post-test rating is preceded by a long period of low stress before or during which an additional measurement of strain is implemented.

Modelling Annoyance from Combined Traffic Noises : An Experimental Study

Annoyance is one of the most studied reactions to noise. Nevertheless, little is known about the effect of the simultaneous occurrence of noise from different sources. Existing models which predict annoyance resulting from combined noise sources are derived from results for single sources and have not yet been validated. The present study empirically investigates actual annoyance as caused from different combinations of road and rail noise in a laboratory experiment. 72 volunteers were exposed to different noise scenarios consisting of combinations of road and rail traffic noise. During noise presentation, test persons had to carry out a task on a personal computer. After each noise scenario, they had to rate their subjective annoyance. A statistical model is derived from the resulting data set, which describes the relationship between noise exposure, task difficulty and annoyance.

Investigation into the subjectively perceived significance of various strain dimensions for informational load

Abstract The currently available uni- or multidimensional inquiry techniques employed in determining the psychological strain resulting from informational load only permit recording of the strain which occurs in each case according to particular aspects. A prerequisite for the targeted employment of such methods is therefore knowledge about the relevant strain foci. The present investigation is based on the assumption that such strain foci can be determined via an analysis of a persons perception of the relevance of particular strain dimensions. The experimental subjects in the present investigation used the method of paired comparison to repeatedly assess five strain dimensions (motor, visual, temporal, mental, and memory strain) which had been preselected using a task analysis on the basis of their significance for the strain occurring during the performance of simple arithmetical tasks (concentration performance test). In the further evaluation it was possible to identify two subgroups which were homo...

Intra- and inter-individual variability of strain during uncompensable heat stress determined from a longitudinal study.

Four mine rescue brigadesmen performed three different standardized trainings in uncompensable heat stress with different equipment, clothing and climatic stress. The strain during these trainings may be considered as typical for training and missions of firemen, mine rescue brigadesmen and subjects working under protective clothing. - During ten years the diverse trainings were repeated. Heart rates and body temperatures were recorded throughout the exposures. A significant linear trend over time only was found for body mass (increase in three of the subjects). Specific physical fitness (fitness per body mass) as well as heart rate or body temperature showed no significant trend over time for initial or final values. The variability of the physiological strain is described in good approximation by normal distributions and shows quite a high magnitude. On base of the whole data set inter-individual components of variance are estimated by a 2-factorial ANOVA (person, time of measurement) with the factor time of measurement nested under the factor person. Confidence intervals for the estimated mean values and respectively, the calculation of the required number of measurements for a given confidence interval are determined by performing a two factorial ANOVA with both factors fully crossed.

Heat acclimation and its relation to resting core temperature and heart rate

Acclimation as an adaptive response of the human body to repeatedly occurring heat stress causes a reduction of core temperature (Tco) and heart rate (HR) at the end of heat exposure. The analysis of three acclimation series (WBGT = 33.5 ◦ C) showed that the lowering of Tco and HR occurred already in the resting period preceding heat stress. The lowered resting values accounted for a substantial part of the beneficial effects of acclimation and may be mainly induced by the physical exercise, as a similar reduction of resting values was also observed under thermally neutral conditions. Expanding the database with short-term acclimation series revealed that the resting values were less reduced for females compared to males, but that the same relations between resting and final Tco and HR existed. The results further suggest that the reduction of resting Tco reflects long term effects of adaptation whereby the resting HR also depends on unspecific situational influences. The lowering of the initial values might be a suitable instrument when considering the effects of acclimation in thermoregulatory models for the assessment of heat stress at the workplace.

Comparison of different layouts of inspection instructions for the production department of a company in the electronic industry

Abstract As the result of keen producer competition in an increasingly international market, product quality has become the quintessential selling point. Early identification of deviations occurring during the production process is also an issue to be tackled by companies. In order to produce a product which lives up to its optimal quality standard, an effective and efficient series of testing methods has been developed, whereby employees utilize specially evolved inspection instructions to carry out the so-called self-inspection. Containing pictorial representations of the products to be checked, these inspection instructions were introduced in work settings. To obtain a point of reference, as to exactly which criteria is to be examined during the inspection, a drawing containing technical inspection instructions was compared with two variants. Of the two variants, the first was a simplified drawing reduced only to the specific details necessary for inspection, and the second was a photograph of the object to be inspected. The ensuing experiment was carried out with the participation of 78 female students at the University of Dortmund who assessed the quality of the inspection by means of a self-administered questionnaire. The verdict reached based upon the subjective evaluation of the three varied depictions verified that comprehension and subsequent transfer of information to the inspection process is dependent upon unambiguous markings of each particular control characteristic, as well as the clarity of the illustration. The photograph included also provided no additional benefit. Relevance to industry The result of the implemented experiment show that institution of inspection instructions from detailed technical drawings to simple line drawings should waived.

An analysis of the subjective strain perceived by parcel-deliverers

Abstract The aim of the present investigation was to determine the level of strain perceived by drivers employed by a parcel-delivery company. A total of ten activities which are typical for the work sequence were the first derived from a task analysis. The subjectively perceived levels of strain associated with the 10 activities were then determined using the method of paired comparisons. 18 experienced parcel-deliverers took part in the investigation. After an analysis of the judgement consistency and the level of concordance among the judges, both of which produced satisfactory results, the 10 activities were scaled unidimensionally. The calculated strain-related scale values are presented and work-design measures are discussed.