Hearing protection - 278 entradas encontradas
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Noise and noise control
Lärm und Lärmbekämpfung [en alemán]
The introductory chapters of this work describe the physics of sound, personal protection against noise, technical measures for the reduction of noise and the vocabulary of technical acoustics. The main body of the text is devoted to noise measurement methods and to technical measures of noise control with practical examples: sound isolation, silencers, noise screens. A computer program used int he solution of noise control problems (involving acoustics and noise toporaphy in factories) is reporduced in full. Explanations are given of the mechanisms by which noise is produced and of possible ways to reduce noise at source.
Allgemeine Unfallversicherungsanstalt, Abteilung für Unfallverhütung und Berufskrankheitenbekämpfung, Adalbert-Stifter-Strasse 65, 1200 Wien, Austria, no date. 102p. Illus. 5 ref.
Hearing conservation program manual for federal agencies
This manual discusses each area of a programme to assist Federal agencies to implement a plan. Sections cover: purpose, scope, policy and responsibility for programme implementation; legislative requirements, implementing elements (delegation of responsibilities, hazard identification, noise control, medical procedures, health education); equipment for control and testing.
Office of Federal Agency Programs, U.S. Department of Labor, Room N 3613, 200 Constitution Avenue, N.W., Washington D.C. 20210, USA, 1984. 149p. Appendices. Illus. Bibl.
Cassano F., Elia G.
Possibilities and limitations of individual hearing protection: insert-type hearing protectors
Possibilitŕ e limiti della protezione acustica individuale: gli inserti auricolari [en italiano]
The noise reduction capacity of 3 types of earplug (glass down, plastic foam, rigid) was tested against 12 types of industrial noise (sound level range 92.9-111.9dB(A)) at 9 frequencies (range: 125-8000Hz). The noise attenuation power of the rigid earplug was significantly less than that of the other two types. The reduction in perceived noise level rarely exceeded 15dB(A) for any of the earplugs.
Rivista di medicina del lavoro ed igiene industriale, Apr.-June 1984, Vol.8, No.2, p.95-108. Illus. 11 ref.
Earplugs - A computer program for simulation of personal hearing protection devices
Written in Basic, this programme allows the user to compare the attenuation capabilities of any hearing protection device versus the environmental octave band analysis for a given workplace and provides a plot of the results. The programme listing is reproduced in its entirety.
American Industrial Hygiene Association Journal, Mar. 1984, Vol.45, No.3, p.154-155. 2 ref.
Ferekidis E., Papafrangos K., Adamopoulos G., Pantazopoulos P.
New objective measuring method for testing hearing protectors
Eine neues objektives Messverfahren bei der Prüfung von Gehörschützern [en alemán]
In addition to comfort and worker acceptance, attenuation is a decisive property in the choice of hearing protectors. Attenuation of sound reaching one (test) ear can be determined by measuring the stapedius reflex of the other (reference) ear. This reflex is a movement of the eardrum caused by contraction of the muscles of the inner ear; it can be measured by plugging the reference ear with a pressure-sensing device. Results with and without various protective devices (medical cotton, glass fibre earplugs, wax earplugs) in the test ear showed that the threshold of the stapedius reflex increases with increasing attenuation, but also with the frequency of the applied sound (500-4000Hz). The advantages of the method are that it does not require judgements by the person being tested, and does not require expensive auxiliary facilities such as special testing chambers.
Zeitschrift für Lärmbekämpfung, 1984, Vol.32, No.3, p.63-66. Illus. 6 ref.
Noise Abatement (Hearing Conservation in Workplaces) Regulations 1983 [Australia - Western Australia]
Regulations issued under authority of the Noise Abatement Act 1972. Contents: measurement and evaluation of noise at workplaces; reduction of noise levels; reduction of noise exposure Leq A8; site identification of noise hazards; suitable hearing protection; hearing tests and medical examinations; management of hearing conservation activities. In the schedules: forms used for the register of designated workers and the annual statistical summary of reference audiometry.
Government Gazette of Western Australia, 21 Oct. 1983, No.77, p.4237-4258.
Criteria for the evaluation of personal hearing protection equipment (earmuffs, earplugs), including regulations, performance standards, selection, use and maintenance are reviewed in the Canadian context.
Occupational Health in Ontario, July 1983, Vol.4, No.3, p.127-142. Illus. Bibl.
Hearing and hearing protection
Answers in layman's terms to commonly asked questions about the need for hearing protection in the workplace, the effect of ear protectors on hearing fellow workers and machinery, the advantages of muffs versus plugs, comfort, foreign bodies in the ears, etc.
Safety Practitioner, Sep. 1983, Vol.1, No.9, p.10-14. Illus. 18 ref.
González Escandon L.A.
La informática agiliza la elección de protectores auditivos
A survey of various methods of evaluating sound exposure levels, and the protection provided by various protective devices. Development and description of a computer programme that can be used to select hearing protection devices according to local needs.
Prevención, July-Sep. 1983, No.85, p.18-24. Illus. 4 ref.
Schulz G., Rublack K., Meister A., Dybowski S., Dubrau K.H., Gretzschel D.
Comparative studies of the noise-reducing capability and the wearing comfort of hearing protectors in the workplace
Vergleichende Untersuchungen der Dämmwirkung und der Trageeigenschaften von Gehörschutzmitteln am Arbeitsplatz [en alemán]
Characteristics of various hearing protectors (cotton wool, plugs, helmets, earmuffs) were tested during the manufacture of screws (continuous noise of 94dB) and in the forging shop of a machinery plant (impact noise of 95-109dB). No differences were found between the noise-reducing powers of the protectors by comparing the temporary reduction in the hearing threshold of the workers, but significant differences were found in their degree of comfort. For long-term use, the best protection is provided by plastic foam plugs (with prolonged resilience). Principles are given for the organisation of a hearing conservation programme.
Zeitschrift für die gesamte Hygiene und ihre Grenzgebiete, 1983, Vol.29, No.2, p.93-98. Illus. 41 ref.
Lempert B.L., Edwards R.G.
Field investigations of noise reduction afforded by insert-type hearing protectors
NIOSH conducted field investigations in 1977 and 1981 to determine the actual noise reduction afforded to industrial workers who used earplugs daily. In-situ attenuation tests of 420 workers at 15 industrial plants were conducted to determine the noise reduction provided by earplugs as they were worn during the workday. The workplace results, when compared to manufacturers' best-fit laboratory test results, indicated that 50% of the workers tested were receiving less than one-half the potential attenuation of the earplugs.
American Industrial Hygiene Association Journal, Dec. 1983, Vol.44, No.12, p.894-902. Illus. 11 ref.
Smith C.R., Broughton R.M., Wilmoth J.N., Mozo B.T.
The effect of relative humidity on the noise attenuation of foam earplugs
5 brands of earplugs were tested. The variables measured were: dry weight, percent moisture content (<5%, 50%, 80% relative humidity) and noise attenuation. Attenuation was measured with a Knowles electronic manikin for acoustic research (KEMAR). Moisture content and relative humidity had significant but very small effects on attenuation (±2%). Some of the earplugs were difficult to insert at high relative humidity.
American Industrial Hygiene Association Journal, Nov. 1983, Vol.44, No.11, p.814-818. 4 ref.
Riko K., Alberti P.W.
Hearing protectors: A review of recent observations
The views of experts speaking at a symposium in Toronto (Canada) in 1980 are reviewed: Methods of quantifying the performance characteristics of hearing protectors, of which the real-ear attenuation at threshold (REAT) is the most widely used; hearing protector performance limits; speech communication problems. In the authors' own laboratory studies, average attenuation of muffs and plugs was less than that expected from manufacturer specifications and than their theoretical potential. Causes were breaking of the seal between head and muff and poor condition of equipment due to age and misuse. Active devices, which electronically modify sound levels under the protector, previously described for military operations, are discussed.
Journal of Occupational Medicine, July 1983, Vol.25, No.7, p.523-526. 30 ref.
Cassano F., Elia G.
Possibilities and limits of hearing protection in workers exposed to industrial noise
Possibilitŕ e limiti della protezione acustica in esposti a rumori industriali [en italiano]
Studies of 5 sets of earmuffs are presented. A small microphone was connected to the ear inside the muff. The noise source was a ball mill in a cement works, and each earmuff was worn by at least 2 different operators. Results varied considerably. Performance of the earmuff depended considerably on the spectral composition of the noise. Only one model satisfied the authors' criterion of attenuation of more than 19dB(A).
Rivista di medicina del lavoro ed igiene industriale, Jan.-Mar. 1983, Vol.7, p.28-38. Illus. 4 ref.
Chung D.Y., Hardie R., Gannon R.P.
The performance of circumaural hearing protectors by dosimetry
Noise attenuation of various models of earmuffs was measured by dosimeters while 101 subjects were exposed to noise levels of 86-108dBA. Criteria studied were: physical conditions of the subject (long hair, safety glasses, cap/turban); age, fit, and condition of earmuffs; noise exposure level. A mean attenuation of 20.3dB was obtained. Most of the problems involved in the use of hearing protectors can be overcome by education of workers and proper fitting.
Journal of Occupational Medicine, Sep. 1983, Vol.25, No.9, p.679-682. 4 ref.
Design of hearing protectors affording acoustic communication
Konstrukcja ochronników słuchu umożliwiajacych łaczność akustycznaą [en polonés]
Miniature earphones were incorporated into 3 models of hearing protector. Different plates for holding the earphones in the ear-caps of the protectors were tested, and the effect of the plates on the attenuation of noise was determined. Attenuation in various frequency bands for different combinations of earphone, mounting plate and ear-cap was tabulated. Incorporation of earphones did not significantly degrade the performance of the protectors.
Prace Centralnego instytutu ochrony pracy, 1983, Vol.33, No.117, p.73-80. Illus.
Laboratory attenuation of earmuffs and earplugs both singly and in combination
The incremental performance to be gained by double ear protection was investigated by measuring real-ear attenuation in 10 subjects wearing, singly or in combination, several types of earplugs and earmuffs. In all cases, the combination plugs + muffs outperformed either device individually, except at 1kHz for one combination. At ≥2kHz all plug + muff combinations provided attenuation approximately equal to the bone-conduction limits of the skull. Below 2kHz, the type of earplug chosen influenced the total attenuation regardless of the type of earmuff used.
American Industrial Hygiene Association Journal, May 1983, Vol.44, No.5, p.321-329. 19 ref.
Mathews J., Calabrese N.
Guidelines for the control of noise at work
This study includes: health effects of noise (temporary and permanent hearing loss, noise-induced stress and psychological problems, noise as a safety hazard, cardiovascular effects); measurement of noise in the workplace; measurement of hearing loss (audiometry); relation between exposure to noise and hearing loss. Daily noise dose limits are given for Australian states (90dBA Leq in most cases) as well as levels of maximum permissible exposure to the unprotected ear (115dBA in 5 states), and compared with exposure limits in some other countries. Statistics on the estimated incidence of hearing impairment in exposed workers are given. Control measures discussed are: noise surveys; new or modified plant and equipment; shields and barriers; sound absorbers; insulating enclosures; soundproof booths; personal protection equipment (ear plugs, muffs); job rotation and rescheduling. The inadequacy of hearing conservation programmes is discussed. There is a list of proposed union policies.
Health and Safety Bulletin, Sep. 1983, No.33, p.1-73. Illus. Bibl.
Lataye R., Damongeot A., Lievin D., Englert M.
Effectiveness and comfort of personal hearing protectors
Efficacité et confort des protecteurs individuels contre le bruit [en francés]
Test results on 151 ear protectors commercially available in France. Ear protectors are divided into 3 categories according to the comfort and protection they afford (noise attenuation given in dB(A) for a typical industrial environment). Given for each protector are: model name, suppliers, noise reduction curve, overall attenuation, comfort level, mechanical characteristics, price, remarks. Criteria are provided for the choice of ear protectors as a function of use.
Travail et sécurité, Oct. 1983, No.10, p.551-577. Illus.
Buller [en sueco]
This publication includes relevant paragraphs from the Labour Protection Act of 1958 (299/58), and the full texts of the Order on noise control in the workplace (No.730/74) (see CIS 75-1295) and of the Order limiting exposure to noise (No.191/82) (see CIS 83-375). It also contains Finnish Standard SFS 4578:S (based on ISO 1999), concerning the measurement of noise exposure in workplaces where noise levels exceed 85dB(A).
National Board of Labour Protection, Box 536, 33101 Tampere, Finland, 1982. 24p.
What do you mean by hearing protector?
Qu'entendez-vous par protecteur anti-bruit? [en francés]
Contents of this information guide intended for workers: physiology of the ear; hearing protectors (action, efficiency, attenuation limits); noise; comparison of the efficiency of various hearing protectors (earmuffs, earplugs, cotton plugs).
Fédération des Travailleurs du Québec, 2100 avenue Papineau, Montréal, Québec H2K 4J4, Canada, 1982. 48p. Illus.
British Cast Iron Research Association
Hearing protectors for foundry personnel
This data sheet provides information on the proper use and choice of various hearing protectors according to specific work situations. A list of British suppliers is also providesd.
BCIRA, Alvenchurch, Birmingham B48 7QB, United Kingdom, 1982. 3p. 6 ref.
Hager W.L., Hoyle E.R., Hermann E.R.
Efficacy of enforcement in an industrial hearing conservation program
The effective efficacy of 4 periods of hearing protection enforcement was compared: the "voluntary period" (1951-1961); the "mandatory period" (1961-1968); the "earmuff period" (1968-1971) and the "OSHA period" (1971-1978). During the voluntary period, hearing loss among noise-exposed workers was very much higher than in a non-noise-exposed group. Mandatory use of personal protective devices was much more effective. Mandatory use of earmuffs exclusively was less effective than mandatory use of personal hearing protection when the worker was given a choice of or earplugs. Enactment of the Occupational Safety and Health Act (the OSHA period) did not result in greater hearing conservation than the earlier mandatory hearing conservation program.
American Industrial Hygiene Association Journal, June 1982, Vol.43, No.6, p.455-465. Illus. 3 ref.
Sadler O.W., Montgomery G.M.
The application of positive practice overcorrection to the use of hearing protection
The purpose of this study was to evaluate a technique which would instil in workers the habit of using hearing protection when working in high-intensity noise areas. Military aeroplane mechanics were assigned to one of 3 groups: group S received a daily safety lecture (controls); members of the other 2 groups were required to perform the correct behaviour 5 consecutive times if they were caught not wearing hearing protection; in group A the leader of the group exerted his/her authority; in group P the leader was also subject to overcorrection practice. The 2 latter groups successfully increased hearing protection use to near-perfect levels; in group S use remained unchanged throughout the study. When the test was terminated, there was a decline towards original hearing protection use levels.
American Industrial Hygiene Association Journal, June 1982, Vol.43, No.6, p.451-454. 13 ref.
Personal hearing protection in industry
Proceedings of a symposium on personal hearing protection in industry, held in Toronto, Canada, in May 1980. 35 papers presented at the symposium are reproduced under the following headings: biological effects of noise; personal hearing protectors - design and standards; personal hearing protectors - evaluation; noise and real-world effectiveness of protectors; practical problems with protectors; hearing conservation programmes - problems of implementation; hearing conservation programmes - evaluation and effectiveness.
Raven Press, 1140 Avenue of the Americas, New York, N.Y. 10036, USA, 1982. 605p. Illus. 430 ref. Price: US$57.50.
Labour Inspectorate (Arbeidsinspectie)
Gehoorbescherming [en holandés]
Contents of this data sheet: hearing level and noise exposure; hearing loss due to exposure to high noise levels; hearing conservation programme; review of hearing protectors (anatomy of ear, earplugs of various types and materials, muff-type protectors, acoustic helmets); noise attenuation afforded by these protectors (calculation of attenuation in dB, estimation); choice of hearing protectors (criteria of comfort, hygiene and durability); requirements to be met by hearing protectors (attenuation; characteristics of earplugs and earmuffs); information to be provided by suppliers of protectors; practical aspects for the introduction of hearing protection (persuasion of noise-exposed workers, effects of irregular wearing of protectors, etc.); audiometric tests; extracts from relevant Netherlands regulations.
Directoraat-Generaal van de Arbeid, Postbus 69, 2270 MA Voorburg, Netherlands, May 1982. 18p. Illus. Price: Glds.0.50.
Aircraft noise and its consequences for man, illustrated by a workplace study
Le bruit en aéronautique et ses conséquences sur l'homme. Illustration par l'étude d'un poste de travail [en francés]
MD thesis. General considerations on noise and hearing; review of studies on acoustics and noise-induced hearing damage. Noise in airports is examined in the light of a workplace study (employment on airport apron and runways). Statistics on hearing loss in airline employees in this occupation; group hearing protection (e.g. health engineering), personal protective equipment. Emphasis is laid on the large number of problems involved for the industrial physician to ensure adequate protection, in noisy environments, for individual employees and the population at large.
Université de Paris VII, Faculté de médecine Xavier Bichat, Paris, France, 1982. 150p. 50 ref.
Comparison of hearing loss in the first year of employment in workers assigned to noise-hazard and non-noise-hazard areas at the state prison industries
Noise abatement and hearing protection procedures implemented in high-noise work areas in the Utah State Prison were evaluated by means of a retrospective matched pair chart study of employees assigned to noise hazard and non-noise hazard areas. No significant difference in hearing loss between the two groups, after one year of exposure, was found. The noise abatement and instruction in hearing protection programme was effective in controlling the problem.
American Industrial Hygiene Association Journal, Jan. 1982, Vol.43, No.1, p.39-42. Illus. 26 ref.
Smith C.R., Broughton R.M., Wilmoth J.N., Borton T.E.
Physical characteristics and attenuation of foam earplugs
The attenuation of noise was evaluated for 5 types of foam earplugs in relation to their physical characteristics of size, weight, density, composition and solubility. All the earplugs had similar physical characteristics; frequency was the most important variable in determining attenuation. The earplugs evaluated provided essentially the same attenuation at frequencies ≥500Hz, but one non-commercial experimental plug provided significantly more attenuation at 125Hz than the others. Considerable attenuation differences were found between chlorinated (PVC) and unchlorinated earplugs. No consistent effects of physical properties on attenuation were found.
American Industrial Hygiene Association Journal, Jan. 1982, Vol.43, No.1, p.31-38. Illus. 12 ref.
Szczepański C., Zaborski L.
The usefulness of various types of individual hearing protectors for sailors
Report of a study to assess the noise reduction efficiency of 10 types of hearing protectors by measuring temporary threshold shift in wearers and by means of a questionnaire; the efficiency was also assessed in relation to the noise spectra encountered in the engine rooms of 4 types of ship. Sailors exposed to noise without hearing protectors had 13-15dB temporary threshold shift in the higher frequencies, whereas the shift was only 5-8dB in those wearing various types of hearing protector. Subjective evaluation of hearing protectors showed a clear preference for imported models.
Bulletin of the Institute of Maritime and Tropical Medicine in Gdynia, 1981, Vol.32, No.3/4, p.213-223. Illus. 12 ref.
Hearing function in adolescent workers exposed to industrial noise and wearing earplugs of the type FPP-ż ("Berużi")
Funkcional'noe sostojanie rabočih-podrostkov, vypolnjajuščih rabotu v uslovijah vozdejstvija proizvodstvennogo šuma pri primenenii protivošumnyh vkladyščej tipa FPP-š ("Beruši) [en ruso]
Audiometric tests and other examinations (reaction times to light and sound, mental performance tests, arterial pressure) were performed in 15 apprentice turners aged 16-18 exposed to a workshop noise of 85-87dBA. The tests and examinations were carried out over 2 weeks: no earplugs were used during the first week, but were worn during the second. Comparison of the results shows the positive effect of wearing ear protectors.
Gigiena truda i professional'nye zabolevanija, Mar. 1981, No.3, p.16-18. 4 ref.
Hörmann H., Lazarus-Mainka G., Lazarus H., Schubeius M.
Influence of wearing hearing protection on speech communication
Sprachliche Kommunikation unter Lärm und das Tragen von Gehörschutz [en alemán]
This report describes the methods used, and gives the results of a study on the influence of sound level, use of earplugs, speech and understanding of verbal communications, the reactions between the speaker and listener, and type of communication, on the understanding of speech communications between 180 pairs of speakers and listeners. Conversation level was reduced by 4dB when hearing protection was used, understanding of verbal messages was reduced by 40%, and exchange of information was considerably slowed down, in comparison to results when no hearing protection was worn.
Bundesanstalt für Arbeitsschutz und Unfallforschung, Postfach 170202, 4600 dortmund 17, Federal Republic of Germany, 1981. 217p. Illus. 66 ref. Price: DM.28.50.
Seppälä A., Niemelä E., Ukkola K.
Use of ear protectors in the paper industry
Kyselytutkimus kuulonsuojainten käytöstä paperiteollisuudessa [en finlandés]
Data were collected for promoting the use of ear protectors in the paper industry, instructing workers in their use and for improving ear protector design. A questionnaire survey was carried out on 237 paper mill workers, 104 of whom had hearing loss. The frequency of hearing loss increased after 10-19 years noise exposure. The 47 workers who used earmuffs complained that these devices caused sweating (57%), pressed on the ears (34%), impeded speech communication (39%). Of the 172 workers using earplugs, 20-28% complained of the hygiene problems of dirty ear plugs. The reasons given by 183 workers not wearing ear protection included; slight risk of hearing loss (44%); difficulty in hearing instructions (42%); perspiration (34%); forgetfulness (26%), protectors mislaid (25%). Improved instruction of workers and better selection of hearing protectors will improve compliance.
Työterveyslaitos, Julkaisutoimisto, Laajaniityntie 1, 01620 Vantaa 62, Finland, 1981. 38p. Illus. 8 ref.
Trynkowska D., Michalski R.
Method for determining the necessary mechanical characteristics of ear protectors for use in specific acoustic conditions, using the example of a ship's engine room
Metoda wyznaczania wymaganych wartości parametrów techniczno-konstrukcyjnych nauszników przeciwhałasowych przeznaczonych do stosowania w określonych warunkach akustycznych na przykładzie maszynowni statków [en polonés]
Description of a method used to determine the mechanical characteristics required of ear protectors in relation to the acoustic environment in which they are to be used. The nomograms and regression equations presented are based on experimental data from the study of correlations between certain parameters (mass, volume, pressure on or adhesion to the wearers' head) in 21 models of ear protectors from different sources and their acoustic effectiveness. The regression factors make it possible to determine the characteristics likely to ensure the acoustic effectivneness required for a given acoustic environment. Details are given of the design of ear protectors for use in the engine rooms of sea-going vessels.
Prace Centralnego instytutu ochrony pracy, 1981, Vol.31, No.110, p.219-234. Illus. 8 ref.
Attenuation of hearing protectors and the NRR factor
The estimated dBA levels at the protected ear were calculated using the ISO-NIOSH method and the Noise Reduction Rating factor (NRR) adopted by the EPA (US Environmental Protection Agency). The dBA level of the protected ear is predicted by subtracting the NRR from the noise level measured as dBC. The sound level was predicted by each method for 144 combinations of 12 noises and 12 protectors. The level predicted using NRR was always higher than measured with a difference range of 0-11.3dBA. Because of this conservative estimation of attenuation and the simplicity of use, the application of the NRR in hearing conservation programmes is recommended.
American Industrial Hygiene Association Journal, Dec. 1981, Vol.42, No.12, p.904-908. 7 ref.
International Organization for Standardization
Acoustics - Measurement of sound attenuation of hearing protectors - Subjective method
Acoustique - Mesurage d'affaiblissement acoustique des protecteurs individuels contre le bruit - Méthode subjective [en francés]
This international standard gives references and definitions, and specifies the conditions for evaluating the sound attenuation of hearing protectors determined at the threshold of audibility: test signals, test site, test equipment, test subjects, test procedure, reporting of data (test protocol). German translation may be obtained from Beuth Verlag GmbH, Burggrafenstrasse 4-7, 1000 Berlin 30, Fed.Rep. of Germany.
Case postale 56, 1211 Genčve 20, Switzerland, 15 Dec. 1981. 4p. Price: SF.15.00.
Puchalska H., Bodemer A.
Assessing the local toxicity of a polyurethane foam used in the manufacture of earplugs
Ocena miejscowego działania toksycznego pianki poliuretanowej, stosowanej do produkcji wkładek przeciwhałasowych [en polonés]
Studies on guinea pigs were carried out to detect the possible irritant effects or skin allergen properties of a polyurethane foam with a high sound-absorption capacity; the Draize method (slightly modified) and the Magnusson and Kligman test were employed. No irritation or sensitisation effect was observed that might suggest a risk of allergic contact eczema; the foam is, therefore, considered completely harmless. Nevertheless attention is drawn to the possible danger of earplugs made from this foam if necessary hygienic precautions are not taken.
Prace Centralnego instytutu ochrony pracy, 1981, Vol.31, No.109, p.141-146. 5 ref.
Sutton G.J., Robinson D.W.
An appraisal of methods for estimating effectiveness of hearing protectors
The protection (reduction in A-weighted sound pressure level at the ear) afforded by a hearing protector varies between wearers and between noises. According to the amount of information available on the noise, various methods exist for the estimation of the effective protection afforded by a protector. The octave-band and the single-number method are reviewed, together with their underlying assumptions. Attenuation data on individual wearers for 7 protectors were used in conjunction with 100 noise spectra to test the validity of these assumptions and to calculate and compare the errors of each method. The best single-number method, representing a practical compromise between accuracy and convenience, is one which generates a rating number to be subtracted from the C-weighted sound pressure level of the noise.
Journal of Sound and Vibration, 8 July 1981, Vol.77, No.1, p.79-91. Illus. 12 ref.
Selection of hearing protectors for optimum speech intelligibility and signal identification
Auswahl des Gehörschutzes im Hinblick auf optimale Sprach- und Signalverständlichkeit [en alemán]
Description of a method of calculating ambient acoustic intensity (after E. Zwicker) which can be used to assess interference with message comprehension and signal identification. Comprehension can be improved for noises between 100 and 500Hz in the third-octave spectrum whereas it is problematic for medium and high frequencies and very low frequencies.
Zeitschrift für Lärmbekämpfung, 1980, Vol.27, No.4, p.145-147. Illus. 7 ref.
USSR State Standards Committee (Gosudarstvennyj komitet SSSR po standartam)
Personal protective equipment - Method of determining sound attenuation by personal protective equipment
Sredstva individual'noj zaščity - Metod opredelenija zvukovogo zaglušenija sredstv individual'noj zaščity [en ruso]
This standard (effective 1 July 1980) applies to insulating clothing, respiratory protective hoods and hearing protectors. Individual sections are devoted to: measuring instruments (audiometers, amplifiers, loudspeakers, sound-level meters and sound chambers); preparation for measurements; measuring procedures; evaluation of results. An appendix contains a measurement protocol.
Izdatel'stvo standartov, Novopresnenskij per.3, 123 557 Moskva, USSR, 27 June 1980. 4p. Illus. Price: Rbl.0.03.
Köckritz S., Panzke K.J.
Noise control, but how?
Lärmbekämpfung aber wie? [en alemán]
Contents of this booklet summarising principles and methods of noise control: basic knowledge; machinery and equipment; noise levels; determination of noise from machinery and installations; noise control techniques (principles, organisation, health engineering, individual hearing protection, built-in noise control at design and construction stages). Appended: practical examples, lists of addresses, of directives and of personal hearing protection.
Verlag Tribüne, Am Treptower Park 28-30, DDR-1193 Berlin, 1980. 63p. Illus. 24 ref. Price: M.1.00.
Edwards R.G., Hauser W.P., Moiseev N.A., Broderson A.B., Green W.W., Lempert B.L.
Field investigation of noise reduction afforded by insert-type hearing protectors.
The results of 840 noise attenuation measurements (test frequency range: 125-8000Hz) on 168 workers in 6 plants indicated that workers were receiving noise protection, from 3 earplug designs, in the range 6dB at 125Hz to 20dB at 3150Hz. Based on laboratory and manufacturers data, the workers tested were receiving 35 to 50% of the potential attenuation of the hearing protectors in use, in terms of noise reduction in dBA. This reduced performance was due to the use of the wrong size of earplug or improper insertion. The degree of protection did not depend on workplace noise level, earplug design, or company policy regarding earplug usage. A difference was found between attenuation received in the first test and in 4 subsequent tests of each worker. Some difference was noticed between workers on active and passive job tasks.
National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, Ohio 45226, USA, Nov. 1978. 43p. Illus. 10 ref.
Influence of hearing protectors on the perception of acoustic signals
Beeinflusst das Tragen von Gehörschutz die Erkennung von akustischen Signalen? [en alemán]
Introduction: modifications of acoustic parameters due to wearing hearing protectors; process of perception of an acoustic signal. Most of this article is devoted to considerations on the relations between the audibility of a signal and the effective hearing threshold when hearing protectors are worn in a noisy environment. Considerations on the problem of diminished ability to identify characteristic noises indicating an incident in the production process. The wearing of hearing protectors results in a decrease in the capacity of hearing and identification, which is frequency-linked. It is advisable to wear hearing protectors with noise-attenuation characteristics which are independent of the frequency of signals.
Zentralblatt für Arbeitsmedizin, Arbeitsschutz, Prophylaxe und Ergonomie, June 1980, Vol.30, No.6, p.204-212. Illus. 25 ref.
Association of German Engineers (Verein Deutscher Ingenieure)
Principle of noise reduction in workshops
Lärmminderung in Betrieben - Allgemeine Grundlagen [en alemán]
This basic directive, which summarises the regulations in force and literature published in the Federal Republic of Germany on this subject, is intended to give information on the general principles of noise control. Sections are devoted to: noise measurement and evaluation (methods, apparatus, parameters); noise charts; noise emitted by specific installations and machines; sound propagation (air, solids); noise reduction (health engineering and financial aspects); noise reduction at source (design, construction and maintenance of machines); limitation of sound propagation (vibration absorption, silencers, enclosure, acoustic barriers, building construction, acoustic treatment of premises); hearing protective measures (workplace design and layout, work organisation, screens, personal hearing protectors), planning. Appended: diagrams and tables for calculations, guidelines for technical agreements (with model), references to literature, regulations and standards.
Beuth-Verlag GmbH, Burggrafenstrasse 4-10, D-1000 Berlin 30, 1980. 27p. Illus. 144 ref. Price: DM.41.90.
Ultrasound installations - Noise emitted
Ultraschallanlagen als Lärmquellen [en alemán]
The introduction to this booklet reviews briefly the nature, physics and production of ultrasound, which is employed in medicine, non-destructive testing, cleaning, welding, machining, etc. Long-term exposure to noise levels exceeding 85dB(A) can cause irreversible deafness due to effects on the middle ear. Review of results of studies on physiological effects and hearing damage, and of ultrasound measurement techniques. Occupational health measures are based on the establishment of TLVs for intensity and noise level, and on rules for personal protection. Example of noise emitted by certain installations and description of health engineering techniques for noise control at the source and in the vicinity of the source (design, enclosure, coverings for vats, workplace design and layout).
Mitteilungen der Sektion Physik 12. Caisse nationale suisse d'assurance en cas d'accidents, Case postale, 6002 Luzern, Switzerland, Dec. 1980. 42p. Illus. 12 ref.
Schröter H.J., Els H.
Acoustic properties of the human head
Die akustischen Eigenschaften des menschlichen Kopfes [en alemán]
Report on research to establish an objective measuring method for determining the reduction in hearing due to wearing personal hearing protectors, without having to rely on subjective evaluation. Part 1: literature survey; comparison between subjective and objective methods. Part 2: measurement of mechanical impedance of tissue layers and bones of the skull. Part 3: design and construction of an artificial head and results of measurements made on it.
Bundesanstalt für Arbeitsschutz und Unfallforschung, Postfach 17 02 02, 4600 Dortmund 17, Federal Republic of Germany, 1980. 179p. Illus. 221 ref. Price: DM.45.00.
Nakamura K., Komoike Y., Horiguchi S.
Audiogram in glass workers
Annual audiometric examinations over 10 years in male workers exposed to noise in 4 glass factories revealed a C5 dip in many workers irrespective of their age. Older workers generally had hearing loss regardless of the length of exposure. A helmet with 2 earplugs hanging from the visor was designed. The main point of the design is that the hanging earplugs would annoy the worker if they were not worn.
Sumitomo Bulletin of Industrial Health, 1 Apr. 1980, No.16, p.19-28. 6 ref.
Métodos experimentales de medida de aislamiento acústico de protectores auditivos
A methodology is proposed for evaluating the sound isolation afforded by hearing protectors: use of white noise source, test premises giving good conditions of reverberation, a dummy head and an online narrow-tape spectrum analyser B & K 2031. The results are claimed to be highly reliable.
Prevención, 1980, No.72, p.7-14. Illus. 7 ref.
Michael P.L., Bienvenue G.R.
Hearing protector performance - An update.
Single-number (A-weighted sound pressure level) and octave-band procedures for presenting hearing protector noise attenuation data are described with their advantages and disadvantages.
American Industrial Hygiene Association Journal, Aug. 1980, Vol.41, No.48, p.542-546. Illus. 4 ref.
Trynkowska D., Michalski R.
Comparative study of protective power of earmuffs of Polish and foreign manufacture
Porównanie własności ochronnych krajowych i zagranicznych nausznikow prezeciwhałasowych [en polonés]
20 models from Poland, Finland, England, USA, USSR, Australia, Hungary, and West Germany were tested. Acoustic efficiency and attenuation power were measured. A rapid method of calculating the attenuation power using a sum of imaginary spectra and a mini-computer is presented. There was a relation between the shape of the attenuation curve and the acoustic efficiency.
Prace Centralnego instytutu ochrony pracy, 1980, Vol.30, No.104. p.63-74. Illus. 6 ref.
Zohar D., Cohen A., Azar N.
Promoting increased use of ear protectors in noise through information feedback.
Hearing loss occurring with and without the use of earplugs was measured in workers of a noisy department of a metal fabrication plant. The results were fed back to individual workers to motivate greater use of ear protectors. Over the next 5 months, use of earplugs rose to 85-90%. Only 10% of a control group of workers given a standard lecture on hearing conservation and subjected to disciplinary threats wore earplugs over the same period. The effectiveness of feedback is seen as a 2-stage process involving individual reinforcement and group adoption of new norms for behaviour.
Human Factors, Feb. 1980, Vol.22, No.1, p.69-79. Illus. 21 ref.
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