The objective of this study was to investigate the noise emitted from a tractor diesel engine, Perkins A63544, using neat diesel fuel and water-diesel emulsions (2, 5, 8 and 10% water by volume). The engine noise was measured at tractor driver’s ear position at four levels of engine speeds ranging from 1600 to 1900 rpm with steps of 100 rpm. No change in the engine components and fuel injection systems was made. The tractor engine sound at driver’s ear position was measured by a HT 157 sound level meter in a test site, which was prepared and managed according to ISO 5131 standard. The time domain engine sound signals were recorded in a computer hard disk. The digital sound in time domain was converted to frequency domain using FFT algorithm. The results obtained from 1/3rd octave frequency band showed that the greatest sound pressure level was observed at firing frequency. The loudest engine sound was found for neat diesel and E2 emulsion, while the combustion of E8 emulsion had the lowest noise emission. The statistical analysis showed significant effects (P < 0.01) of the engine speed and fuel type parameters on the engine noise. The overall engine noise increased when increasing the engine speed. Comparing to neat diesel, using water-diesel emulsion did not change the overall engine noise emission significantly (P > 0.01). The results also showed that the overall engine noise was very high and could be dangerous for the driver health. The driver’s exposure time should be less than one hour/day and there is needed to implement the noise control program for the tractor and driver.
