Noise in hospitals is known to hinder communication among staff, causing annoyance, irrita-tion and fatigue, and detrimentally impact the quality and safety of healthcare. High noise levels and noise-induced stress impact negatively on staff performance and wellbeing. The paper presents the results of the assessment of working conditions at workstations in selected hospital rooms in Poland. Environmental measurements were conducted in the rooms of a second referral level hospital in Warsaw. Measurements of quantities characterising noise, were carried out at selected workstations in the rooms occupied by the Radiodiagnostics Unit, Operating Suite, Central Sterilisation, Endoscopic Examinations Unit, Analytical Laboratory and Water Treatment Station. In order to assess the exposure to noise at workstations, the measured quantities of noise characteristics were compared to the exposure limit values. The test results showed that the exposure limit values and exposure action values are not exceeded.
In Poland about 2300 companies are producing packaging. Noise measurements at workplaces in selected companies producing plastic, paper, cardboard, wood, metal and glass packaging were carried out. The scope of measurements included not only the A-weighted and the C-weighted sound pressure levels but also the sound pressure levels in the 1/3 octave bands with the centre frequency from 10 kHz to 40 kHz (i.e. in the frequency range of ultrasonic noise). The results of the measurements showed that the ultrasonic noise exposure at certain workplaces in the case of the companies producing metal, plastic and wood packaging exceeded the limit values established in the national Regulation. The description of the ultrasonic noise measurement method, the identification of ultrasonic noise sources in companies producing packaging and the examples of ultrasonic noise exposure at workplaces are presented in the paper.
An increasing number of workplaces uses ultrasonic techniques in many different fields of industry. Widespread applications are welding, cleaning and cutting. Frequently, airborne ultrasound is emitted as a side effect at machines using ultrasonic technology. Employees working at or in the vicinity of these workplaces are being exposed to the airborne ultrasound field. As the exposure to airborne ultrasound poses a potential health hazard, the quantitative determination and the assessment of this exposure to ultrasound is essential. Since measurement procedures established in the audible frequency range are not sufficiently capable to quantify the exposure of airborne ultrasound, a new measurement procedure adapted to the specifics of ultrasound was needed. Within the scope of Ears II, a European research project, the Physikalisch-Technische Bundesanstalt (PTB) together with the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA of DGUV), has developed a measurement procedure for the determination of the occupational exposure to airborne ultrasound. The development of the measurement procedure was based on the detailed characterization of the ultrasound field of a representative industrial sound source in the laboratories of PTB and IFA. Those investigations revealed the large nearfield and the pronounced speckle-like structure of the sound field. The drafted measurement procedure is capable to cope with those and further challenges arising when measuring airborne ultrasound. In addition, the measurement procedure was applied to different ultrasonic modalities during field tests in industry to verify the practicability for investigations in occupational safety and health. Finally, the results led to a procedure which enables the determination of the occupational exposure to ultrasonic noise with a minimized expenditure of time and effort. Here, we present the novel measurement procedure and the results of the field tests.
A method for identifying panel acoustic contribution to the interior sound field formed by complex vibrating structure using double-layer patch nearfield acoustic holography (NAH) based on equivalent source method is presented. A sound field separation technique with two semi-closed surfaces covering the panel of interest is proposed to process the measurements. The free radiated field of the vibrating panel can be recovered by removing the incoming field of reflections and the scattered field on the surface from the mixed field, which can be further used as the input of NAH to reconstruct the acoustic quantities on the panel surface. The net acoustic power flow from this vibrating panel is used as criterion to evaluate the relative contributions to the interior sound field in enclosure, and is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity of the panel. Numerical simulation results demonstrate that the proposed technique can be well applied in identification of the relative acoustic contributions of individual vibrating panels to the interior sound field in enclosure and provide guidance for structural optimization design.
