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Experimental verification of the usefulness of selected infrasound and low-frequency noise (ILFN) indicators in assessing the noise annoyance of wind turbines

Wszołek Tadeusz, Mleczko Dominik, Pawlik Paweł, Kłaczyński Maciej, Małecki Paweł, Stępień Bartłomiej

Vibrations in Physical Systems

2022

Vol. 33, nr 3

art. no. 2022315

This paper presents an overview of the indices used in evaluating ILFN noise, based on C and G weighting curves and LC-LA difference parameter, as well as curves compared to the loudness threshold curve. The research section includes measurement results of wind turbine (WT) noise along with proposed indicators for evaluating this noise in the infrasound and low-frequency bands at distances of 250 m, 500 m and 1000 m from the turbine. The results obtained indicate low noise levels in the infrasound band, lower than the threshold curves from a dozen or so dB in the upper part of this band to nearly 60 dB in the lower part. The LC-LA indicator has been shown to be of poor utility for evaluating low-frequency noise, with the LG indicator reasonably useful for evaluating infrasound noise.

Numerical investigation of the basilar membrane vibration induced by the unsteady fluid flow in the human inner ear

Wahl Philipp, Ziegler Pascal, Eberhard Peter

Archive of Mechanical Engineering

2020

LXVII, nr 4

381--414

For a deeper understanding of the inner ear dynamics, a Finite-Element model of the human cochlea is developed. To describe the unsteady, viscous creeping flow of the liquid, a pressure-displacement-based Finite-Element formulation is used. This allows one to efficiently compute the basilar membrane vibrations resulting from the fluid-structure interaction leading to hearing nerve stimulation. The results show the formation of a traveling wave on the basilar membrane propagating with decreasing velocity towards the peaking at a frequency dependent position. This tonotopic behavior allows the brain to distinguish between sounds of different frequencies. Additionally, not only the middle ear, but also the transfer behavior of the cochlea contributes to the frequency dependence of the auditory threshold. Furthermore, the fluid velocity and pressure fields show the effect of viscous damping forces and allow us to deeper understand the formation of the pressure difference, responsible to excite the basilar membrane.