Kerstin Persson Waye

Characterizing noise and perceived work environment in a neurological intensive care unit

The hospital sound environment is complex. Alarms, medical equipment, activities, and ventilation generate noise that may present occupational problems as well as hinder recovery among patients. In this study, sound measurements and occupant evaluations were conducted in a neurological intensive care unit. Staff completed questionnaires regarding psychological and physiological reactions to the sound environment. A-weighted equivalent, minimum, and maximum (L(Aeq),L(AFMin),L(AFMax)) and C-weighted peak (L(CPeak)) sound pressure levels were measured over five days at patient and staff locations. Acoustical descriptors that may be explored further were investigated, including level distributions, restorative periods, and spectral content. Measurements near the patients showed average L(Aeq) values of 53-58 dB. The mean length of restorative periods (L(Aeq) below 50 dB for more than 5 min) was 9 and 13 min for day and night, respectively. Ninety percent of the time, the L(AFMax) levels exceeded 50 dB and L(CPeak) exceeded 70 dB. Dosimeters worn by the staff revealed higher noise levels. Personnel perceived the noise as contributing to stress symptoms. Compared to the majority of previous studies, this study provides a more thorough description of intensive care noise and aids in understanding how the sound environment may be disruptive to occupants.

Wind turbines—low level noise sources interfering with restoration?

Wind turbines generate a low level noise and would thus not be expected to cause annoyance and disturb rest. In a society where people are being exposed to an increasing noise load, moderate and low level noise sources may also be perceived as annoying and hence inhibit restoration. This article presents an analysis of two socio-acoustic studies of wind turbine noise with the emphasis on perception, annoyance and consequences for restoration. It is hypothesized that low and moderate stressors such as wind turbine noise could have an impact on health. The risk seems to be higher if restoration is, or is perceived to be, impaired and also for certain groups of individuals. The observations warrant further studies.

Observations of the Relationship Between Noise Exposure and Preschool Teacher Voice Usage in Day-Care Center Environments

Although the relationship between noise exposure and vocal behavior (the Lombard effect) is well established, actual vocal behavior in the workplace is still relatively unexamined. The first purpose of this study was to investigate correlations between noise level and both voice level and voice average fundamental frequency (F₀) for a population of preschool teachers in their normal workplace. The second purpose was to study the vocal behavior of each teacher to investigate whether individual vocal behaviors or certain patterns could be identified. Voice and noise data were obtained for female preschool teachers (n=13) in their workplace, using wearable measurement equipment. Correlations between noise level and voice level, and between voice level and F₀, were calculated for each participant and ranged from 0.07 to 0.87 for voice level and from 0.11 to 0.78 for F₀. The large spread of the correlation coefficients indicates that the teachers react individually to the noise exposure. For example, some teachers increase their voice-to-noise level ratio when the noise is reduced, whereas others do not.

Effects of train noise and vibration on human heart rate during sleep: an experimental study

Objectives Transportation of goods on railways is increasing and the majority of the increased numbers of freight trains run during the night. Transportation noise has adverse effects on sleep structure, affects the heart rate (HR) during sleep and may be linked to cardiovascular disease. Freight trains also generate vibration and little is known regarding the impact of vibration on human sleep. A laboratory study was conducted to examine how a realistic nocturnal railway traffic scenario influences HR during sleep. Design Case–control. Setting Healthy participants. Participants 24 healthy volunteers (11 men, 13 women, 19–28 years) spent six consecutive nights in the sleep laboratory. Interventions All participants slept during one habituation night, one control and four experimental nights in which train noise and vibration were reproduced. In the experimental nights, 20 or 36 trains with low-vibration or high-vibration characteristics were presented. Primary and secondary outcome measures Polysomnographical data and ECG were recorded. Results The train exposure led to a significant change of HR within 1 min of exposure onset (p=0.002), characterised by an initial and a delayed increase of HR. The high-vibration condition provoked an average increase of at least 3 bpm per train in 79% of the participants. Cardiac responses were in general higher in the high-vibration condition than in the low-vibration condition (p=0.006). No significant effect of noise sensitivity and gender was revealed, although there was a tendency for men to exhibit stronger HR acceleration than women. Conclusions Freight trains provoke HR accelerations during sleep, and the vibration characteristics of the trains are of special importance. In the long term, this may affect cardiovascular functioning of persons living close to railways.

Indoor Measurements of Noise at Low Frequencies - Problems and Solutions

Due to standing waves, the sound pressure level within a room may vary as much as 20–30 dB at low frequencies. Principal properties of low-frequency sound in rooms are illustrated by simulations, and sound pressure distributions as well as the performance of Swedish and Danish measurement methods are studied by measurements in three rooms. For assessment of annoyance, mainly areas of the room with high sound pressure levels are of interest, since persons present in such areas are not helped by the existence of lower levels in other areas. The level that is exceeded in 10% of the room (L10) is proposed as a rational and objective target for a measurement method. The Swedish method showed results close to the target, but, due to a doubtful use of C-weighting in the scanning, it may give results below the target in case of complex sounds. The Danish method was found to have a high risk of giving results substantially below the target, unless complainants can precisely appoint measurement positions, where the sound is loudest/most annoying. An alternative method using measurements in four three-dimensional corners of the room is proposed. This easy and straightforward method seems to give reliable results close to the proposed target.

A detailed study of low-frequency noise complaints

From 203 cases of low-frequency complaints a random selection of twenty-one cases were investigated. The main aim was to answer the question whether the annoyance is caused by an external physical sound or by a perceived but physically non-existing sound, i.e. low-frequency tinnitus. Noise recordings were made in the homes of the complainants, and the complainants were exposed to these in blind test listening experiments. Furthermore, the low-frequency hearing function of the complainants was investigated, and characteristics of the annoying sound were matched. The results showed that some of the complainants are annoyed by a physical sound (20–180 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40–100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance -or at all audible – in any of the investigated cases, and none of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases.

Mean F0 Values Obtained Through Standard Phrase Pronunciation Compared With Values Obtained From the Normal Work Environment: A Study on Teacher and Child Voices Performed in a Preschool Environment

Mean fundamental frequency (F(0)) values are often used in research on vocal load. In this study, we examine how the mean F(0) differs when evaluated through pronouncing a standard phrase as compared to the mean F(0) obtained in a real work/play environment. We also examine how the F(0) values change throughout the day. The study was performed in a preschool, nine adult female preschool teachers and 11 children participated. The participants wore a digital recorder equipped with an accelerometer, which was attached to the neck. In the study, the participant first pronounced a standard phrase in a controlled environment; thereafter, the voice was recorded in the environment where both children and adults normally reside throughout the day, denoted by the work/play environment. For each participant, the procedure was repeated four times throughout the day. Analyses showed that the F(0) values of the childrens and adults voices were significantly higher when recorded in the work/play environment as compared to the controlled environment. The average difference was 36 Hz for adults and 24 Hz for children. Previous studies have shown an increase of F(0) over the day for teachers. In this study, an increase between morning and afternoon values was found amounting to 8 Hz for adults and 24 Hz for children. For the child population, this increase was statistically significant. However, the total changes over the day revealed a somewhat more complex scheme, with an increase of F(0) in the morning, a decrease during lunch, and finally an increase in the afternoon. This pattern was verified statistically for the joint child-adult population.

Human sleep and cortical reactivity are influenced by lunar phase

Summary Various human biological functions adhere to a circadian rhythm that to some extent may be affected by environmental factors, including light and temperature [1]. Recent evidence from Cajochen et al. [2] indicates that human sleep is influenced by the cycle of the moon, measured in conditions precluding the potential impact of nocturnal lunar illumination Here in a similarly retrospective study of 47 healthy volunteers (mean age 23.3, S.D. ±2.9 years) we demonstrate that total sleep time decreases by 25 minutes and cortical reactivity to environmental stimuli during sleep increases around full moon, and rapid eye movement (REM) sleep latency lengthens by 30 minutes around new moon. The findings strengthen the notion that human sleep is modulated by lunar phase but point to important deviations from the study of Cajochen et al . that need to be addressed, particularly with regard to individual susceptibility.

Wind Turbine Noise Propagation over Flat Ground: Measurements and Predictions

Noise from wind turbines is of concern in the planning process of new wind farms, and accurate estimations of immission noise levels at residents nearby are required. Sound propagation from wind turbine to receiver could be modelled by a simplified standard model assuming constant meteorological conditions, by an engineering method taking atmospheric and ground propagation conditions into account, or by a more exact model. Epidemiological studies have found a higher frequency of annoyance due to wind turbine noise than to other community noise sources at equal noise levels, indicating that the often used simplified model is not sufficient. This paper evaluates the variation of immission sound levels under the influence of meteorological variation and explores if the prediction of levels could be improved by taking the effect of wind speed on sound propagation into account. Long-term sound recordings and measurements at a distance of 530 m from a wind turbine show that the simplified standard model predicts the average sound pressure levels satisfactorily under downwind conditions, and that a more complex propagation model might not be needed for wind turbine noise at a relatively short distance. Large variations of sound immission levels at the same wind speed were however present. Statistical analysis revealed that these variations were influenced by meteorological parameters, such as temperature, static pressure and deviation from ideal downwind direction. The overall results indicate that meteorological factors influence the noise generated by the wind turbine rather than the sound propagation.

CargoVibes: human response to vibration due to freight rail traffic

The aim of this paper is to present an overview of the research concerning human response to vibration conducted in the EU FP7 CargoVibes project. The European Union-funded project CargoVibes involved 10 partners from 8 nations and ran from April 2011 to April 2014. The project was concerned with railway-induced ground-borne vibration affecting residents close to freight lines, with one work package that investigated human response to vibration, including sleep disturbance, community annoyance and the production of a best practice guide for evaluating response. Laboratory trials at the University of Gothenburg were used to measure the effects of vibration on sleep. Physiological and psychological impacts of vibration exposure were found. TNO led a meta-analysis (N = 4129) to determine exposure–response relationships for railway vibration, with existing data for community response supplemented with field studies in the Netherlands and Poland. The University of Salford led production of a guidance document that presents the state of the art regarding vibration measurement and assessment. Specific topics in the guide include human perception, evaluation methods, annoyance, sleep impacts and non-exposure factors. The outcomes presented in this paper represent a significant advance in the understanding of the human response to railway vibration and a step towards much needed harmonization of assessment methods.