2012-02-01 12:00 - Messages

A tuned vibration absorber reduces the risk of hand-arm vibration syndrome for a grass trimmer

Prolonged use of electric grass trimmer exposes the user to the risk of hand-arm vibration syndrome. A simple approach for the suppression of hand-arm vibration in electric grass trimmer is presented. The proposed system is a tuned vibration absorber (TVA). The results indicated that minimum vibration level was related to the position of the TVA on the shaft of electric grass trimmer. The tuned vibration absorber when installed to the electric grass trimmer attenuated the vibration total value by 67%. This significantly reduces the risk of hand-arm vibration syndrome.

Source : Tuned vibration absorber for suppression of hand-arm vibration in electric grass trimmer. Ko Ying Hao, Lee Xin Mei, Zaidi Mohd Ripin. International Journal of Industrial Ergonomics; Volume 41, Issue 5, September 2011, Pages 494-508. doi:10.1016/j.ergon.2011.05.005


Occupational diving is associated with hearing loss caused by noise

L’article présente une étude des causes de la perte d’audition chez le plongeur professionnel. Les raisons principales identifiées sont l’exposition au bruit et les accidents barotraumatique. Une perte auditive tant subjective qu'objective a été associée à l'exposition professionnelle au bruit, mais non pas avec la fréquence de plongée ou avec une histoire de barotraumatisme de l'oreille moyenne. La plongée sans incident n’apparait pas être responsable de la baisse d’audition.


Source : Goplen FK, Aassen T, Gronning M et al. Hearing loss in divers: a 6-year prospective study. Eur Arch Otorhinolaryngol. 2011 ; 268: 979-85


Voir aussi : Anses • Bulletin de veille scientifique no 15 • Santé / Environnement / Travail • Juillet 2011, p.81


Les recycleurs s’ouvrent à l’isolation acoustique

Ils sont peu visibles. Mais les chimistes, pétrochimistes, papetiers, recycleurs et autres producteurs de matériaux naturels partagent la même volonté farouche de se développer dans la construction. Avec le lancement du Grenelle de l'environnement en 2007 et la  nouvelle réglementation thermique (RT 2012) généralisant la norme Bâtiment basse consommation (BBC), les recycleurs s’ouvrent à l’isolation acoustique : Le Relais recycle les fibres des jeans usagés en panneaux et rouleaux d’isolation thermique et acoustique pour le bâtiment, Foamglass produit des matériaux d’isolation incombustibles à partir de pare-brises et vitres de bâtiments recyclés grâce à la technique des mousses de verre.

Source : Les outsiders de la construction. L'Usine Nouvelle,  N° 3260 | 03/10/2011 | Enquête


According to new research, approximately 20 percent of all Americans over the age of 12 suffer hearing loss in at least one ear

The new study, led by Johns Hopkins researchers and published in the Nov. 14 Archives of Internal Medicine, is thought to be the first to estimate hearing loss on the national scale rather than on specific cities or populations. Using the World Health Organization's definition for hearing loss (not being able to hear sounds of 25 decibels or less in the speech frequencies), the researchers found that overall, about 30 million Americans, or 12.7 percent of the population, had hearing loss in both ears. That number jumped to about 48 million, or 20.3 percent, for people who have hearing loss in at least one ear. These numbers far surpass previous estimates of 21 to 29 million.

Source : Study Shows Hearing Loss on a Grand Scale in U.S. Population. Walter, L.; ESH Today, Nov 15.


 Voir aussi: HEALTH CARE REFORM-Hearing Loss Prevalence in the United States. Lin, F.R., Niparko, J.K., Ferrucci, J. Arch Intern Med. 2011;171(20):1851-1852. doi:10.1001/archinternmed.2011.506


Relatively high intelligibility scores are possible with an in-ear integrated hearing protection communications device.

Integrated hearing protection systems are designed to enhance free field and radio communications during military operations while protecting against the damaging effects of high-level noise exposure. A study was conducted to compare the effect of increasing the radio volume on the intelligibility of speech over the radios of two candidate systems, in-ear and muff-style, in 85-dBA speech babble noise presented free field. At the highest volume, subjects achieved 79% with the in-ear device but only 69% with the muff-style device, averaged across the gender of listener/talker pairs and consonant position. These results indicate that normal hearing users can achieve reasonably high radio communication scores with integrated in-ear hearing protection in moderately high-level noise that provides both energetic and informational masking. The adequacy of the range of available radio volumes for users with hearing loss has yet to be determined.

Source : Speech understanding in noise with integrated in-ear and muff-style hearing protection systems. Sharon M Abel, Ann Nakashima, Douglas Saunders; Noise and Health, vol 13 (2011), issue 55, pages 378-384. DOI: 10.4103/1463-1741.90289


For certain types of shocks, acute reductions in finger blood flow can be predicted from the rms acceleration.

This study investigated how reductions in finger blood flow depend on shock repetition rate and the peak and rms magnitude of acceleration. Different repetition rates (1.3-83.3 s(-1)) and different peak magnitudes (10-88 ms(-2) peak) but the same rms acceleration (10 ms(-2) rms) caused similar decreases in blood flow in fingers on exposed and unexposed hands. Shocks with a 83.3 s(-1) repetition rate, peak magnitude of 10 ms(-2) and rms acceleration of 10 ms(-2) provoked greater reduction in finger blood flow than shocks with the same peak magnitude but lower repetition rate (21 or 5.3 s(-1)) and lower rms acceleration (5 or 2.5 ms(-2)).

Source: Acute effects of mechanical shocks on finger blood flow: influence of shock repetition rate and shock magnitude. Ye Y, Mauro M, Bovenzi M, Griffin MJ. Int Arch Occup Environ Health. 2011 Oct 2.


Professional driving and prolapsed lumbar intervertebral disc diagnosed by magnetic resonance imaging

Objectives The aim of this study was to investigate whether whole-body vibration (WBV) is associated with prolapsed lumbar intervertebral disc (PID) and nerve root entrapment among patients with low-back pain (LBP) undergoing magnetic resonance imaging (MRI).
Methods A consecutive series of patients referred for lumbar MRI because of LBP were compared with controls X-rayed for other reasons. Subjects were questioned about occupational activities loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about LBP. Exposure to WBV was assessed by six measures, including weekly duration of professional driving, hours driven at a spell, and current 8-hour daily equivalent root-mean-square acceleration A(8). Cases were sub-classified according to whether or not PID/nerve root entrapment was present. Associations with WBV were examined separately for cases with and without these MRI findings, with adjustment for age, sex, and other potential confounders.
Results Altogether, 237 cases and 820 controls were studied, including 183 professional drivers and 176 cases with PID and/or nerve root entrapment. Risks associated with WBV tended to be lower for LBP with PID/nerve root entrapment but somewhat higher for risks of LBP without these abnormalities. However, associations with the six metrics of exposure were all weak and not statistically significant. Neither exposure–response relationships nor increased risk of PID/nerve root entrapment from professional driving or exposure at an A(8) above the European Union daily exposure action level were found.
Conclusions WBV may be a cause of LBP but it was not associated with PID or nerve root entrapment in this study.

Source : http://www.sjweh.fi/show_abstract.php?abstract_id=3273

Some of the tested gloves meet the vibration transmissibility criteria specified in the current standard (ISO 10819,1996) but none of them could be classified as an AV glove

To improve the reliability of the anti-vibration (AV) glove test defined in the current  standard, a revised version of the standard has been proposed. This study examined the rationale behind the major revisions of the standard and evaluated the major technical aspects of the revised method through an experiment. To help evaluate the AV glove criteria, the effects of the glove on the grip strength were also examined. The glove vibration transmissibility values were measured with a new spectrum proposed in the current study. The results suggests the new spectrum can greatly simplify the test without changing the original test results, and it should be adopted in the further revision of the standard. The results of this study also strongly support the proposed major revisions in the instrumentation and test  procedures. The glove that reduced the grip strength the least was also the one that reduced the most vibration, which suggests that the negative and positive effects of the glove can be balanced in its design. This study can significantly help improve the current standard on the test. The results of this study can also be directly used to help select appropriate AV gloves. 

Source : An evaluation of the proposed revision of the anti-vibration glove test method defined in ISO 10819 (1996). Welcome D.E. et al. International Journal of Industrial Ergonomics, 42 (2012) 143e155.




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