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Noise, infrasound and ultrasound in two types of helicopters

Dejan Živković, M Hrnjak, G Basarić, Pešić Nebojša

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Abstract

The aim of work was to measure the entire noise level and to accomplish the octave analysis as well as to measure ultrasound and infrasound levels inside and around two types of helicopters. The results of measurement showed that the entire noise levels (92 dB(A) -113 dB(A)) and octave sound level pressures in the observed work regimes of helicopter motors exceed the permissible levels. The spectrum analysis of infrasound showed that it does not exceed the permissible levels in any octave band. The spectrum analysis of ultrasound showed it exceeds the permissible level only in the third octave band with the mid frequency of 20 kHz around the second type of helicopter.

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What this paper is about

The aim of work was to measure the entire noise level and to accomplish the octave analysis as well as to measure ultrasound and infrasound levels inside and around two types of helicopters. The results of measurement showed that the entire noise levels (92 dB(A) -113 dB(A)) and octave sound level pressures in the observed work regimes of helicopter motors exceed the permissible levels. The spectrum analysis of infrasound showed that it does not exceed the permissible levels in any octave band. The spectrum analysis of ultrasound showed it exceeds the permissible level only in the third octave band with the mid frequency of 20 kHz around the second type of helicopter.

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Available abstract

The aim of work was to measure the entire noise level and to accomplish the octave analysis as well as to measure ultrasound and infrasound levels inside and around two types of helicopters. The results of measurement showed that the entire noise levels (92 dB(A) -113 dB(A)) and octave sound level pressures in the observed work regimes of helicopter motors exceed the permissible levels. The spectrum analysis of infrasound showed that it does not exceed the permissible levels in any octave band. The spectrum analysis of ultrasound showed it exceeds the permissible level only in the third octave band with the mid frequency of 20 kHz around the second type of helicopter.

Key concepts: Octave band, Infrasound, Octave (electronics), Acoustics, Noise (video), Measure (data warehouse), Environmental science, Physics

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