Fractal Analysis of Noise Signals of Sampo and John Deere Combine Harvesters in Operational Conditions

Combine harvesters are the source a large amount of noise in agriculture. Depending on different working conditions, such machines can have significant effect hearing condition drivers. Therefore, it is highly important to study signals caused by these and find solutions for reducing produced noise. The present was carried out order obtain fractal dimension (FD) Sampo John Deere combine operational conditions. combines were recorded with engine speeds, gear states, locations. Four methods direct estimations FD waveform time domain three sliding windows lengths 50, 100, 200 ms employed. results showed that Fractal Dimension / Sound Pressure Level [dB] varied ranges 1.44/96.8 1.57/103.2 1.23/92.3 1.51/104.1, respectively. cabins reduced enhanced amounts, With an increase length speed combines, increased. In other words, size suitable window depends extraction method calculating FD. also type gearbox used could tangible trend changes