Návrh hemisféry pro měření hladiny akustického výkonu dle ISO 3745

Abstract

This master thesis deals with a design of a special device for measuring sound power level according to ISO 3745. This special device is called a hemisphere. This thesis was divided into several parts. The theoretical part explains a basic terminology of sound propagation. This chapter continues to the essence of measuring noise and subsequent determination of the sound power that generates of source noise. In the next part of the thesis ISO 3745 is explained. The topic of the thesis was based on the requirements of company Honeywell, which received an anechoic chamber from VŠB – TU Ostrava last year. The requirements of company Honeywell are explained in the next part. In relation to these requirements a technical design of the hemisphere was created. There is the description of the elements from which the hemisphere consists of and also there is a mention of what limitations are placed on them. After the creation of the hemisphere, a mathematical model was created. This mathematical model determines a basic process for calculation of the sound power level. Subsequently, there was a verification measurement in semianechoic chamber, where the reference noise source was used. The sound power levels for the individual octaves of this source are determined by a manufacturer. The values determined by the manufacturer were used to compare them with the measured values. At the end of this thesis, an evaluation was carried out to assess whether the hemisphere is working properly.