Impacts of leisure activity noise levels on safety procedures and policy in the industrial environment

Prior research has concentrated on noise levels in the workplace. However, people who work in noisy environments might also have noisy leisure activities which could contribute to hearing loss or interfere with recovery time. This study investigated work and leisure noise levels experienced by workers in a manufacturing plant. Workers were surveyed to determine leisure activities and use of hearing protection. Measurements were taken to compare noise levels of the leisure activities with those in the workplace. Noise levels of the leisure activities had a mean of 99 dB with a standard deviation of 8 dB, while the mean for the noise levels in the work place was 89 dB with a standard deviation of 8 dB. Although workers are required to wear hearing protection when exposed to occupational noise levels above 85 dB, only 36% of the survey respondents wear hearing protection in the leisure environment.

Since the cost of hearing loss is frequently borne by organizations, even though some of loss might be attributable to leisure activities, it is prudent for facility engineers and plant managers to provide educational information emphasizing noise levels and associated risks for specific leisure activities, as well as to provide protection to employees for leisure use.     

Occupational noise exposure of fishermen aboard small and medium-scale fishing vessels

There is little information about occupational noise exposure of fishermen working on small and medium-scale fishing vessels, mainly because of the difficulty of conducting noise exposure surveillance in such occupations. The objective of the current study was to evaluate the exposure of this group of workers to occupational noise using a combined measurement and questionnaire approach. Sound pressure levels were measured aboard 24 fishing vessels at all working or resting locations and during speeding and slow-down moods of the engine. The average existence times of the crew at such locations were collected using a questionnaire. The average daily noise exposure levels (L_EP,d,8h) for engine mechanics in all vessel types (91.2–94.3 dBA) and the tiller operators in gill/trammel and purse seining vessels (84.7–88.4 dBA) exceeded the NIOSH recommended exposure limit of 85 dBA. Other crew members were found to be exposed, on average, to daily noise exposure levels slightly lower than the recommended one (81.6–83.5 dBA). However, direct personal dosimetry for five crew members revealed daily noise exposure levels 1.1–5.1 dBA higher than the calculated averages, which might be attributed, partly, to sources of uncertainty. The results of this study suggest that small and medium-scale vessels fishermen are at high risk of NIHL, calling for development and enforcement of suitable interventions for hearing protection of the workforce of this sector.     

Assessment of potential noise-induced hearing loss with commercial “Karaoke” noise

A study was conducted to assess the noise levels of popular Karaoke environments in Korea and the degree of potential noise-induced hearing loss due to commercial Karaoke noise. Using 18 subjects with normal hearing, a two-way, mixed-factors experimental design was used with two independent variables of “noise source” (no-singer, one-singer, and two-singer conditions) and “music type” (Trot, Ballad, and Rock music). For each experimental condition, average sound pressure levels and maximum sound pressure levels were measured. For assessing amount of temporary hearing threshold shift as a measure of potential hearing loss index, pure-tone audiometry was applied for measuring subjects’ hearing threshold levels of both ears before and after 100 min exposure to Karaoke noise. Questionnaires from 155 actual Karaoke users were also obtained to evaluate realistic user subjective perception on the Karaoke environment. Results showed that noise levels of typical Karaoke singing environments were higher than 95 dBA, with maximum noise levels often exceeded the US OSHA's non-permissible 115 dBA level. Further statistical analysis of hearing threshold shift revealed that up to 8 dB of significant hearing loss was found at the most important human hearing frequency band, centered at 4000 Hz, after about less than 2 h of Karaoke noise exposure, indicating that Karaoke facilities may pose a serious threat to noise-induced hearing loss. Along with some ergonomic/safety issues, practical hearing protection strategies are suggested and discussed.

Relevance to industry

Since noise levels from popular commercial Karaoke facilities are found to be potentially dangerous, the Karaoke-related industries, of supporting a big consumer market of entertainment, need to provide safer environments to protect naive users from potential hearing loss. Providing better design of Karaoke facilities with some ergonomic intervention strategies (such as proper sound absorptive treatment in Karaoke rooms, displaying warning signs of potential hearing loss, and setting up an upper safety volume limit in the Karaoke machine, etc.) may help those industries not only contribute for consumer protection but also develop better market with strong ethical and legal support in the future.     

Effect of electronic ANR and conventional hearing protectors on vehicle backup alarm detection in noise

An experiment was conducted wherein masked thresholds (using ascending method of limits) for a backup alarm were obtained in pink and red noise at 85 and 100 dBA for 12 participants immersed in a probability monitoring task and wearing a conventional passive hearing protection device (HPD, an earmuff or a foam earplug), an active noise reduction (ANR) headset, or no HPD at all (only in 85 dBA noise). Results revealed statistically significant between-HPD differences in red noise (from 2.3 to 3.1 dB) and in the 100-dBA noise level (from 2.6 to 4.3 dB). An additional finding, which corroborates other studies using different protocols, was that masked thresholds in 85-dBA noise were significantly lower (from 3.2 to 4.4 dB) for the occluded conditions (wearing an HPD) than for the open-ear (unoccluded) condition. This result refutes the belief among many normal-hearing workers that the use of HPDs in relatively low levels of noise compromises their ability to hear necessary workplace sounds. Actual or potential applications of this research include (a) the selection of appropriate HPDs for low-frequency-biased noise exposures wherein signal detection is important and (b) gaining insight into the appropriateness of ANR-based HPDs for certain industrial noise environments.     

Perceived exertion during a self-imposed pace of work for a group of cleaners

Nine cleaners were monitored for four hours while performing their ordinary work. They rated their perceived exertion on Borg's CR-10 scale every five minutes and their heart rates were recorded every minute. It was found that the subjects worked on a physiological ‘steady-state’ level, meaning that their heart rates were about the same regardless of the work performed. Their ratings of perceived exertion varied, however, but were all ‘fairly strong’ or stronger. During more than 80% of the time, the work periods on the different tasks were shorter than 15 min. On the basis of the results of a bicycle ergometer test, it was determined that the actual level of exertion during the ordinary work corresponded to about 35% of the subjects' estimated maximal oxygen uptake.

Most subjects had back symptoms and more than half of them reported symptoms involving the neck, shoulders, wrists and hands. The varying intensities indicate where the problems are most critical.     

Noise exposed of the operators of combine harvesters with and without a cab

A considerable number of the combine harvesters in Turkey are rather old and used without cabs resulting in unhealthy working conditions for their operators. Noise is one of the detrimental factors. This study deals with determining and comparing the noise exposed on the operators of the combines with and without a cab used for wheat harvesting in Turkey. The sound pressure levels (dB) at octave band center frequencies (31.5–8000 Hz) and the sound levels (dBA) at the ear level of the operators were measured on 37 different combine harvesters with four different makes and different years from 1976 to 2001. Fifteen of the combines were without a cab, another 15 had original cabs while remaining seven combines had cabs mounted on them after manufacturing.

The sound pressure levels were in a decreasing trend from the lower frequencies to higher frequencies. This trend was more noticeable for the combines with original cab and with the cab mounted after manufacturing compared to the ones without cab. The use of a cab was more effective in the insulation of the noise at the medium and higher frequencies, which have more bothersome effect compared to the lower frequencies. The sound pressure levels were 75–102 dB and 46–89 dB at low (31.5–500 Hz) and high (500–8000 Hz) frequencies for all combines, respectively. The sound pressure levels at the frequency of 4000 Hz at which the human ear is most sensitive were 6–17 dB lower for the combines with the cabs mounted after manufacturing and 9–28 dB lower for the ones with the original cabs compared to the combines without cab. The sound levels were 85–90, 81–83, and 76–81 dBA for the combines without cab, with cab mounted after manufacturing, and with original cab, respectively.

The study showed that the use of a cab was useful in the insulation of the noise, particularly at higher frequencies. In addition, it protects the operator from the factors having detrimental effects on the working efficiency such as high temperature and dusty environment. The authors strongly recommend mounting of a cab on to the combines currently being used without a cab in rental system in Turkey to provide healthy working conditions for their operators.     

Does risk recognition affect workers’ hearing protection utilisation rate?

In industrial environments, it is very likely to find several workers sharing the same workplaces and being exposed to the same noise pressure levels, who have different perceptions of the risks they are exposed to. These different perceptions could lead to different workers’ attitudes and behaviours. The present study was carried out with a sample of 434 industrial workers exposed to noise pressure levels greater than the action level defined in Portuguese legislation (85 dB(A)). The study aims to analyse the role of individual risk recognitions in hearing protection devices’ (HPD) utilisation rates. A questionnaire was developed to assess workers’ risk perception of high-noise exposure and their utilisation of HPD. The multivariate data analysis of the several variables considered revealed that risk recognition in general and self-efficacy in particular, plays a significant role as a predictor of workers’ behaviour with respect to the use of HPD. Furthermore, these results do suggest that risk recognition should be considered as an essential issue in the design and implementation of any Hearing Conservation Program, in particular in what concerns workers’ training.

Relevance to industry

Results obtained do suggest that workers’ risk recognition could have an important impact on noise exposure protective behaviours and these could be used to design and conceive successful industrial Hearing Conservation Programs.     

Comparison of four task-based measurement indices with full-shift dosimetry in a complicated noise environment

This study was conducted to verify the agreement between four task-based measurement indices (TBMs) and full-shift dosimetry in a complicated noise environment. The study involved six production lines and 63 fixed jobs from an automobile wheel manufacturer. The subjects were simultaneously measured by the TBMs and a personal dosimeter, and 158 measurements were completed in total. There were two methods for measuring the level-at-task: average dosimetry noise level (ADL) and direct measure noise level (DML), and two methods for measuring time-at-task: worker diary (WD) and observation diary (OD). As for the differences, Pearson correlation coefficients, paired-samples t-tests, scatter and Bland–Altman plots were undertaken to assess the agreement between TBMs and the dosimeter. The results indicated that the TBMs agreed well with the personal dosimeter; the differences between them ranged from 0.16 to 3.07 dBA. The DML of level-at-task was less than the ADL result of 3.39 dBA and using the DML could cause a systematic error. The results showed that the TBMs from WD were as accurate as the TBMs from OD, and the WD recorded 88% of the task transitions of OD. Our research suggests that the TBMs, which uses ADL and OD, can be a reliable and more feasible as a cost effective strategy for assessing the full-shift noise exposures in practice. The study showed a high degree of agreement between TBM and dosimetry in fixed jobs and complicated noise environments. However it is not clear how well the agreement between TBM and dosimetry is in mobile jobs, and thus requires further studies to assess these environments.     

The effect of noise on edge orientation computations

This paper studies the effect of image noise on edge orientation computations. It is found that noise affects estimation of edge orientation in a complex way, but this is simplified for those ‘circular’ operators which act in a strictly vectorial manner. In that case the distribution of edge orientations is closely gaussian for gaussian image noise. These results have important consequences for object location schemes based on the generalised Hough transform - especially when noise is high or contrast is low. Suprisingly, the consequences are much less serious with impulse noise.     

Physiological cost of apple-farming activities

Seventeen agricultural male workers, aged between 21 and 56 years, were investigated in the field during six different job-activities of apple-farming: pruning, weeding, hand and mechanical spraying, mowing and picking. Pulmonary ventilation and oxygen consumption were recorded for short periods by Oxylog, while heart rate was monitored for more than 24 hours by Holter's method. The farmers also rated the work intensity according to Borg's RPE scale.

Pulmonary ventilation ranged on average between 13 and 30 1/min and oxygen consumption between 500 and 1300 ml/min, with a relative aerobic cost between 15 and 40%, in the different work activities. Heart rate varied on average between 80 and 94 beats/min with a relative cardiac cost between 20 and 30%. The physiological criteria (oxygen uptake and cardiac response) and the subjective rating of fatigue gave a substantially similar evaluation of the work strain, ‘moderate-heavy’ for mowing, weeding and picking, ‘moderate’ for pruning and hand spraying, ‘light’ for mechanical spraying of pesticides. On the whole, apple-farming can be evaluated as ‘moderate’ intensity, thanks to the mechanisation implemented in reducing the work-load and the work-time of many job activities.     

Facilitating simultaneous engineering in the automotive industry via high speed networks, control passing and face-to-face video: Results from the car project

The European automotive industry requires frequent interaction and transfer of data between geographically dispersed designers and engineers at all stages of the product introduction process. The RACE CAR project identified and demonstrated Integrated Broadband Communications (IBC)-supported applications to support this process and improve competitiveness. User requirements for workstation-based, multi-media facilities including conferencing were identified. Two experiments were designed to investigate the role of face-to-face video and the means by which participants organise and control their interactions. These are critical issues in the multi-cultural, international environment of the European automotive industry. In the first experiment groups of three users solved a cooperative, screen-based, object manipulation task supported by different levels of communication. ‘Linked computers plus an audio link’ resulted in significantly faster completion times than either ‘audio alone’ or ‘linked computer plus audio and face-to-face video’. ‘Linked computers plus audio’ was also perceived as the most effective communications media. The passage of cursor via verbal agreement was successfully managed. Video was generally considered beneficial for initial introductions, assessing understanding and facilitating a stronger feeling of group identity.

In the second experiment, subjects were grouped under ‘chaired’ or ‘free-for-all’ conditions and linked via (1) audio and linked computers or (2) audio, linked computers and face-to-face video. The task was similar to Experiment 1 and attempts to introduce contention were made through adding hidden, sub-goals. The task took significantly less time to complete in the ‘video chaired’ condition than the ‘non-video chaired’ or ‘video free-for-all’ conditions. This suggests that video has an important role in enabling a chairperson to control the meeting. Contention was not successfully achieved.

The results of the experiments suggest face-to-face video may be useful in chaired meetings and to develop ‘team’ feeling. A free-for-all method of control passing was seen as most appropriate although problems in achieving contention in Experiment 2 meant the impact of disagreement was not fully investigated. The results are discussed in relation to the European automotive industry and areas for further study identified. Relevance to industry

The European automotive industry, which maintains distinct engineering functions in disparate countries, is striving to reduce the length of its design life cycle by improving communications between designers and engineers. The studies described in this paper provide information of use to the developers and procurers of systems intended to support this process. In particular issues relating to the relevance of face-to-face video and use of control mechanisms for co-operative computer-mediated work.     

White noise theory of robust nonlinear filtering with correlated state and observation noises

In the existing ‘direct’ white noise theory of nonlinear filtering, the state process is still modelled as a Markov process satisfying an Itô stochastic differential equation, while a ‘finitely additive’ white noise is used to model the observation noise. We remove this asymmetry by modelling the state process as the solution of a (stochastic) differential equation with a ‘finitely additive’ white noise as the input. This enables us to introduce correlation between the state and observation noises, and to obtain robust nonlinear filtering equations in the correlated noise case.     

Thermal comfort and clothing insulation of resting tent occupants at high altitude

Thirty-nine males and 18 females, in six groups, participated in six high altitude treks (each lasting 3–4 weeks and climbing up to 5500 m) in the Himalaya and Karakoram. Inverse relationships between mean overnight total insulation (sleeping bag plus clothing) and air temperature in tents were recorded for all treks. Average overnight thermal sensations varied little with air temperature as the subjects modified their clothing insulation to maintain thermal sensations warmer than ‘neutral’ for all treks. For combined treks, subjects adjusted their mean overnight total insulation up to 7 clo for thermal sensations of between 0 (‘neutral’) and +1 (‘slightly warm’) on average, measured on the standard seven-point thermal sensation scale developed for everyday low-altitude conditions. Very few subjects (3% of all daily responses, on average) reported ‘cool’ or ‘cold’ sensations. General tent discomfort increased with altitude suggesting that subjects interpreted tent comfort predominantly in terms of thermal outdoor conditions.     

Synergistic effects of noise and hand-arm vibration on distortion product otoacoustic emissions in healthy subjects

An experimental study has been performed on the effect of exposure to noise (N), vibration (V), and combined noise and vibration (NV), on the distortion product otoacoustic emission (DPOAE) level. The aim of the study is investigating the possible synergistic effect of noise and vibration, increasing the risk of damage to the hearing function due to noise only.Twelve normal-hearing volunteers were randomly exposed to hand arm vibration (HAV) only, noise only, and HAV and noise simultaneously. The exposure consisted of five consecutive sessions interspersed with quiet periods. DPOAEs were recorded during the quiet intervals following each exposure session, and during recovery, and compared to their baseline level, and among different test treatments. An ad hoc acquisition system developed in Labview was used to record high frequency-resolution DPOAE spectra in a suitably short time. Time-frequency filtering, based on the wavelet transform, was used to separate the DPOAE components coming from different generation mechanisms.The three test treatments, N, V, and NV, yielded significantly different results. The condition affecting most significantly all DPOAE component levels was the exposure to vibration only, causing a statistically significant increase of the signal level during all the exposure periods, with a decreasing trend during recovery. Also the exposure to noise only, N, caused a DPOAE level increase, statistically significant for the long latency (LL) DPOAE component. Only when exposure to noise was in combination with vibration, the zero-latency (ZL) component was clearly suppressed during the exposure. The results suggest a synergistic adverse effect of noise and vibration on the cochlear function.Relevance to industryThe simultaneous exposure to noise and hand arm vibration is a very common industrial scenario. The risk that exposure to mild noise levels could interfere with the exposure to vibration, enhancing the adverse effect on the hearing function, should be considered to optimize prevention strategies at the workplace.     

Experiments with an adaptive Bayesian restoration method

This paper describes a Bayesian restoration method applied to two-dimensional measured images, whose detector response function is not completely known. The response function is assumed Gaussian with standard deviation depending on the estimate of the local density of the image. The convex hull of the K-nearest neighbours (KNN) of each ‘on’ pixel is used to compute the local density. The method has been tested on ‘sparse’ images, with and without noise background.     

Circularly orthogonal moments for geometrically robust image watermarking

Circularly orthogonal moments, such as Zernike moments (ZMs) and pseudo-Zernike moments (PZMs), have attracted attention due to their invariance properties. However, we find that for digital images, the invariance properties of some ZMs/PZMs are not perfectly valid. This is significant for applications of ZMs/PZMs. By distinguishing between the ‘good’ and ‘bad’ ZMs/PZMs in terms of their invariance properties, we design image watermarks with ‘good’ ZMs/PZMs to achieve watermark's robustness to geometric distortions, which has been considered a crucial and difficult issue in the research of digital watermarking. Simulation results show that the embedded information can be decoded at low error rates, robust against image rotation, scaling, flipping, as well as a variety of other common manipulations such as lossy compression, additive noise and lowpass filtering.     

Evaluation of acoustic beacon characteristics for navigation tasks

The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.     

Evaluation of acoustic beacon characteristics for navigation tasks

The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.     

The discomfort produced by noise and whole-body vertical vibration presented separately and in combination

This study investigated the prediction of the discomfort caused by simultaneous noise and vibration from the discomfort caused by noise and the discomfort caused by vibration when they are presented separately. A total of 24 subjects used absolute magnitude estimation to report their discomfort caused by seven levels of noise (70–88 dBA SEL), 7 magnitudes of vibration (0.146–2.318 ms^? 1.75) and all 49 possible combinations of these noise and vibration stimuli. Vibration did not significantly influence judgements of noise discomfort, but noise reduced vibration discomfort by an amount that increased with increasing noise level, consistent with a ‘masking effect’ of noise on judgements of vibration discomfort. A multiple linear regression model or a root-sums-of-squares model predicted the discomfort caused by combined noise and vibration, but the root-sums-of-squares model is more convenient and provided a more accurate prediction of the discomfort produced by combined noise and vibration.     

Defining a taxonomy of output modalities from an HCI perspective

The paper addresses an issue that must be resolved to produce a scientifically sound and practically useful reference model for intelligent multimedia presentation systems (IMP systems), namely that of providing, from the point of view of Human-Computer Interaction (HCI), a systematic understanding of the types of output information to be presented by IMP systems. The term ‘medium’, as it is used in the context of multimedia systems, is too coarse-grained for distinguishing between different types of output information. The paper introduces the notion of (representational) ‘modalities’ to enable sufficiently fine-grained distinctions to be made. For the term itself to be meaningful, ‘multimodal’ presentations must be composed of unimodal representations. In the approach presented, unimodal representations are defined from a small number of basic properties whose combinations specify the ‘generic’ level of a taxonomy of unimodal output modalities. Additional basic property distinctions serve to generate the more fine-grained ‘atomic’ and ‘sub-atomic’ levels in a hierarchical fashion. The taxonomy is set up with the aim of satisfying four basic requirements, viz. completeness, orthogonality, relevance and intuitiveness. A concluding discussion illustrates the practical use of the taxonomy.