Tractor noise and vibrations adversely affect the health of operators, reduce work efficiency, and interfere with
the creation of a comfortable working environment. Electric-powered next-generation tractor systems lack
masking effects in engines. Moreover, as various excitation sources contribute to noise, rapid causal analysis of
numerous transfer paths is necessary. An operational transfer path analysis (OTPA) is an experimental method
used to analyze the energy transfer of noise and vibration. This paper proposed an operational transfer path
analysis (OTPA) network for agricultural tractor using a multi-layer transfer function matrix and a contribution
calculation method. A root cause analysis of the noise transfer considering the entire tractor system was per
formed using only the response signals. Acoustic and vibration signals were acquired from 83 sensor channels on
the sources and transfer paths of the tractor. Based on the measured signals, an analysis network was constructed
using air- and structure-borne paths. The signals predicted by the developed OTPA model matched the overall
response level and frequency domain characteristics of the sound pressure signals measured from an actual
tractor. Additionally, air- and structure-borne noise contributions were quantitatively evaluated according to the
frequency. Analysis results showed that the structure-borne noise was dominant. In addition, the floor panel of
cab had a high contribution to the engine 4th-order noise(four times of the engine rotational frequency), and the
front glass comprises a structural mode in the 684 Hz band. The contribution from the rear mounts showed that it
was the dominant paths for transmitting vibrations to the tractor cab. Moreover, it was higher than that from the
front part. This difference indicated that a separate design for the front and rear mounts should be needed. The
contribution of air-borne noise increased as the engine speed increased. The air-borne noise was primarily
contributed by the wheel noise, with the rear wheels contributing more than the front wheels. The results of this
study can contribute to improvements in noise and vibration comfort performance of the agricultural tractor cab.