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The use of Tranquility Rating for urban spaces

100%

Idczak J. , Juros K. , Chojak A. , Mleczko D.

Vibrations in Physical Systems

2021

tom Vol. 32, nr 1

art. no. 2021104

The Tranquility Rating coefficient (TR) is a tool proposed for assessing the quality of urban green areas, which considers both visual and acoustic aspects. This paper aims to verify how the proposed TR coefficient works for the assessment of the audiovisual quality of a typical urban space in a vicinity of an arterial road. Three different versions of the same urban space are considered: loud and visually unappealing (current state), quiet and visually unappealing (after considerable traffic reduction), and visually appealing and quiet (after redesigning). The values of noise levels required for the calculation of TR are taken from the noise maps based on the in-situ measurements, and the values of the percentage ratio of the features which are natural or man-made but contained within the visual scene (NCF) are taken from a survey conducted in the research. The results show that for the urban areas, even with very low noise levels, the TR is described as “unacceptable”. This may indicate the need for introducing an amendment for TR to be used in typical urban areas.

The effect of sound-absorbing walls on the acoustic properties of the modelled unit cell of a sound-absorbing metamaterial

88%

Chojak A. , Binek W. , Chojnacki B. , Pawlik J. , Idczak J.

tom Vol. 34, nr 2

art. no. 2023212

Cavity-based metamaterials are usually designed for sound absorbing or sound scattering properties. They are built of combinations of ducts and slits, which in the case of acoustic absorbers are designed to maximize the sound absorption at resonance frequencies through the appearance of the viscothermal losses. The unit cells are designed under the assumption of perfectly rigid walls, shared by all the analytical models. Sound absorbing properties of the structures result from viscothermal losses in small ducts. The paper discusses the influence of adding sound absorption to the walls in the numerical model on the results of the observed sound absorption coefficient. It is demonstrated that the resulting sound absorption of the structure varies with changing sound absorption coefficient of the walls of the structure. The same observations are made for 3D-printed measurement samples, showing the importance of including the sound absorption of the walls in the modelling process.