Graham, Neil Anthony (1974) Airborne noise reduction of agricultural tractor cabs. PhD thesis, University of Warwick.

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Abstract

This thesis is concerned with the airborne noise reduction
of agricultural tractor cabs. The characteristics of the
noise radiated from a non-cab-equipped tractor have been
evaluated and used in conjunction with the classical
theories of airborne sound transmission loss to predict the
airborne noise reductions of tractor cabs. An experimental
cab has beep constructed and used to evaluate these
predictions.
The theoretical and experimental airborne noise reductions do
not show a good agreement. This has been shown to be due to
two ressons. Firstly, there are anomalies in the classical
airborne sound transmission loss theory whereby the theoretical
and experimental sound transmission loss spectra do not show
good agreement. Secondly, one-dimensional standing wave
resonances in the cab cavity have been shown to give rise to
an irregular plateau in the experimental airborne noise reduction
spectra.
Anomalies have been shown to exist between airborne sound
transmission loss theory and reverberant room transmission
loss measurements. These have arisen because the theory has
not hitherto considered panel flexure. Modifications have
been introduced which take account of panel flexure and these
show that the dependence of classical theory on the angle of
incident excitation is false and angular dependence occurs
on the transmitted side of the panel, giving rise to a
coincidence effect on the transmitted side which is independent
of the angle of incidence. These modifications give rise to
complete qualitative explanation of the shape of empirical
airborne sound transmission loss spectra. Quantitative
modifications have not been introduced because of lack of
information regarding the angular nature of the transmitted
waves.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	T Technology > TL Motor vehicles. Aeronautics. Astronautics
Library of Congress Subject Headings (LCSH):	Farm tractors -- Noise
Official Date:	August 1974
Dates:	Date Event August 1974 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Marples, V.
Sponsors:	Massey Ferguson Manufacturing Co.
Extent:	121, [19] p.
Language:	eng

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