Sound-Absorbing and Insulating Enclosures for Ultrasonic Range

Dobrucki, Andrzej; Zoltogorski, Bronislaw; Pruchnicki, Piotr; Bolejko, Romuald

doi:10.2478/v10168-010-0014-4

Cited by 13 publications

(11 citation statements)

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“…In the relation between objective and subjective results of exposure to this hazard factor in the work environment, it is necessary to take appropriate preventive actions (technical organizational and medical actions) (Regulation of the Minister of Health and Social Policy of 30 May 1996 Regulation of the Minister of Economy and Labour of August 5, 2005). Devices emitting high frequency noise should be equipped by the manufacturers with means of technical protections against noise (soundproof and isolation casings shields or silencers) (Dobrucki et al, 2010) In the case when those ways of noise limitations at workplaces are impossible, the employer should fit the workers with hearing protections or plugs. When the measurements of noise parameters in reference to an 8-hour workday the MAI values are exceeded, a properly time of work or even a full stop of activity should be implemented as well as employees' rotation.…”

Section: Discussionmentioning

confidence: 99%

Technical Note. An Objective and Subjective Study of Noise Exposure within the Frequency Range from 10 kHz to 40 kHz

Smagowska¹

2013

Archives of Acoustics

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The paper consists of study results of exposure to high frequency noise at metalworking workplaces. The study was carried out using objective methods (measurements of parameters characterizing the noise) and subjective studies (questionnaire survey). Metalworking workplaces were located in a steel structure (e.g. deck gratings) of the manufacturing plant. The results are equivalent sound pressure levels in the 1/3 octave frequency bands with center frequencies from 10 kHz to 40 kHz in reference to an 8-hour workday equal to approximately 81-105 dB at most of the tested workplaces and exceed permissible values. The questionnaire survey of annoyance high frequency noise (i.e. in the audible frequency and low ultrasound range) was conducted among 52 operators of machines. Most of the workers describe the noise as: buzzing, insistent, whistling and high-pitched squeaky. Respondents specify the noise levels occurring at workplaces as: loud, impeding communication, highly strenuous and tiring.

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Section: Discussionmentioning

confidence: 99%

Technical Note. An Objective and Subjective Study of Noise Exposure within the Frequency Range from 10 kHz to 40 kHz

Smagowska¹

2013

Archives of Acoustics

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“…A solution to this problem could be the application of the reverberant standard method in a special miniaturized test chamber (Dobrucki et al, 2010) or the use of the impulse method (the tone-burst technique).…”

Section: Methods Of Determination Of Sound Absorption Coefficientmentioning

confidence: 99%

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

Pleban

2013

Archives of Acoustics

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Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0• to 60• . The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

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“…Some of these devices can be operated in sealed (fully closed) sound-insulating enclosures [11] and then ultrasonic noise outside such enclosure is, in the majority of cases, very small and negligible from the point of view of its harmful effect on humans [4,5]. Therefore, fully sealed enclosures (especially those provided with an inner lining of sound absorbing material) turn out to be a very effective measure of ultrasonic sound reduction [11][12][13][14][15][16][17][18][19][20][21][22]. The parameter characterising acoustic effectiveness of an enclosure in scope of its ability to attenuate the sound penetrating through it is called "the sound insulation of acoustic enclosure" (or "the sound insulation of enclosure") in applicable standards and literature of the subject [11,[15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Reducing the harmful effects of noise on the human environment. Sound insulation of industrial skeleton enclosures in the 10–40 kHz frequency range

Mikulski

2020

J Environ Health Sci Engineer

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Purpose The purpose of the research is to work out a method for determining the sound insulation of acoustic enclosures for industrial sources emitting noise in the frequency range of 10–40 kHz and apply the method to measure the sound insulation of acoustic enclosures build of different materials. Methods The method is developed by appropriate adaptation of techniques applicable currently for sound frequencies of up to 10 kHz. The sound insulation of example enclosures is determined with the use of this newly developed method. Results The research results indicate that enclosures (made of polycarbonate, plexiglass, sheet aluminium, sheet steel, plywood, and composite materials) enable reducing the sound pressure level in the environment for the frequency of 10 kHz by 19–25 dB with the reduction increasing to 40–48 dB for the frequency of 40 Hz. The sound insulation of acoustic enclosures with a sound-absorbing material inside reaches about 38 dB for the frequency of 10 kHz and about 63 dB for the frequency of 40 kHz. Conclusion Some pieces of equipment installed in the work environment are sources of noise emitted in the 10–40 kHz frequency range with the intensity which can be high enough to be harmful to humans. The most effective technical reduction of the associated risks are acoustic enclosures for such noise sources. The sound pressure level reduction obtained after provision of an enclosure depends on its design (shape, size, material, and thickness of walls) and the noise source frequency spectrum. Realistically available noise reduction values may exceed 60 dB.

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Sound-Absorbing and Insulating Enclosures for Ultrasonic Range

Cited by 13 publications

References 1 publication

Technical Note. An Objective and Subjective Study of Noise Exposure within the Frequency Range from 10 kHz to 40 kHz

Technical Note. An Objective and Subjective Study of Noise Exposure within the Frequency Range from 10 kHz to 40 kHz

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

Reducing the harmful effects of noise on the human environment. Sound insulation of industrial skeleton enclosures in the 10–40 kHz frequency range

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