In the present study, we aimed to determine the changes of indoor radon concentrations depending on various environmental parameters, such as the outdoor temperature, relative humidity, and air pressure, in university building premises of different applications and heights. The environmental parameters and indoor radon concentrations in four different premises were measured each working day over an eight-month period. The results showed that the indoor radon levels strongly depended on the outside temperature and outside relative humidity, whereas the weakest correlations were found between the indoor radon levels and indoor and outdoor air pressures. The obtained indoor radon concentration and environmental condition correlations were different for the different premises of the building. That is, in two premises where the ventilation effect through unintentional air leakage points prevailed in winter, positive correlations between the radon concentration and outside temperature were obtained, reaching the values of 0.94 and 0.92, respectively. In premises with better airtightness, negative correlations (R = −0.96 and R = −0.62) between the radon concentrations and outside temperature were obtained. The results revealed that high quality air isolation in premises could be an important factor for higher indoor radon levels during summer compared to winter.

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Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

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Traffic‐generated noise accounts for 60–80% of the noise prevailing in towns. With the aim of reducing the impact of noise on humans, measures and methods of fighting noise in towns and residential areas should be developed. In the majority of cases, noise suppression walls (barriers) are one of the most suitable means in tows to reduce the dispersion of noise to residential territories. Acoustic properties of materials to be used for noise walls were investigated and, on the basis of the obtained findings, the most suitable materials with regard to noise reduction were proposed. A noise‐suppression chamber was designed and installed for the experimental investigation into acoustic properties. Separate materials (fibreglass, wood chipboard, gypsum cardboard, foam polystyrene) were used for the experiment by composing various structures of different modifications. With the aim of evaluating the capacity of different materials to suppress noise, a coefficient was used to evaluate noise suppression in a material thickness measuring unit. Efficiency of the noise reduction structures used in the experiment is described by a separate index. Different materials differently suppress the dispersion of noise of various frequencies, whereas the structures of wood chipboards (10 mm) filled with fibreglass or rock wool are the most efficient in all frequency ranges compared with acoustic properties of other structures used during the experiment. Santrauka 60–80 % miestuose vyraujančio triukšmo kelia transportas. Kad triukšmo poveikis žmogui būtų mažesnis, būtina ieškoti priemonių ir būdų triukšmui miestuose ir gyvenvietėse mažinti. Daugeliu atvejų miestuose vienas iš tinkamiausių metodų tam yra triukšmo slopinimo sienelės (barjerai). Tiriant nustatyta triukšmo sienelėms naudotinų medžiagų akustinės savybės bei, atsižvelgiant į gautus rezultatus, siūlomos triukšmo slopinimo požiūriu tinkamiausios medžiagos. Akustinių savybių eksperimentiniams tyrimams buvo sukonstruota ir įrengta triukšmo slopinimo kamera. Tirta skirtingos medžiagos (stiklo vata, medžio drožlių plokštės, gipso kartono plokštės, putų polistirolas) bei iš jų sudarytos konstrukcijos, panaudojant įvairias modifikacijas. Skirtingų medžiagų geba slopinti triukšmą vertinta nustačius koeficientą. Jį taikant gaunamas garso slopinimas medžiagos storio mato vienete. Bandymuose naudojamų konstrukcijų, skirtų triukšmui mažinti, efektyvumas apibūdinamas tam tikru rodikliu. Įvairios medžiagos skirtingai slopina įvairių dažnių garso sklidimą, o medžio drožlių plokštės (10 mm) konstrukcijos su stiklo arba akmens vatos užpildu tam tinka geriausiai. Palyginti su kitomis bandymuose panaudotomis konstrukcijomis efektyviausiai slopinamas beveik visų dažnių diapazonų garsas. Резюме Основным источником шума в городах, составляющим 60–80% общего шума, является транспорт. В целях снижения шумового воздействия на человека необходимо найти пути и средства уменьшения шума в городах и населенных пунктах. Во многих случаях одним из наиболее приемлемых методов уменьшения распространения шума в городах и жилых районах являются звукоизоляционные экраны. Объектом исследования настоящей статьи были акустические свойства материалов, из которых конструируются звукоизоляционные экраны. Полученные результаты показали, какие из проанализированных материалов наиболее применимы для поглощения шума. Для экспериментального исследования акустических свойств материалов была построена шумопоглощающая камера. Исследовались различные виды материалов (стекловата, прессованные древесные плиты, гипсокартон, пенополистирол), а также их конструкции разной модификации. Акустические свойства материалов эффективно поглощать шум характеризуются определенными индикаторами. Наиболее эффективно поглощающими шум всех диапазонов частот по сравнению с другими материалами оказались конструкции, в которых применялись прессованные древесные плиты.