Predicting emission of noise by machinery and equipment on the basis of the global acoustic quality index

The task consisted in defining the global acoustic quality index of machinery, which is the function of the following frequency indices: - acoustic power, - distance between the workstation and machinery, - radiation directivity, - impulse and impact noise, - distribution of the noise spectrum. Machinery is acoustically dangerous if the value of the global index is greater than 1. This means that the admissible value of acoustic quality will be exceeded at a workstation. Two alternative methods of determining the global acoustic quality index were also developed: a method that uses standardized methods of determining the sound power level and the inverse method. Four series of experimental tests were carried out to verify the determination of the global acoustic quality index. As a result global indices were determined for four engine-generators. To determine the sound power level, the inverse method was used with simultaneous 16-channel registration o data. Each of the generators was modelled with one omnidirectional substitute source. Modelling took place within the frequency range from 10 Hz to 12500 Hz. Software for predicting emission of noise by machinery in industrial spaces was developed on the basis of the global acoustic quality index. Optimization carried out in the developed software with the use of a genetic algorithm is aimed at minimizing the noise hazard at the workstation.