Abstract
Specifying sound sources and their transfer path characteristics, that worse
vehicle sound interior quality, is essential to select a suitable countermeasure to improve the
sound quality. A number of transfer path analysis methods to obtain their characteristics have
been developed at present. However, obtaining high accuracy transfer functions in structure-borne
and airborne sounds simultaneously is difficult in the conventional methods because
crosstalk among transfer functions and noise are included in the measured transfer functions.
This paper describes a time domain transfer path analysis method that can obtain transfer
functions and the contributions of structure-borne and airborne sounds in a vehicle´s interior.
Vibration acceleration and sound pressure signals at the sound sources (reference points) and
the sound pressure signal in the cabin (response point) were measured simultaneously to
obtain the transfer functions when the test vehicle was driven. Principle component regression
method (PCR), which can eliminate both crosstalk among transfer functions and noise in the
measured data, was employed to obtain transfer functions accurately. In addition, a
normalization procedure was developed to perform the PCR for combined data sets in which
both vibration acceleration and sound pressure signals exist.
By applying the above methods, a highly accurate and efficient transfer path analysis method
was developed that does not require a hammer test.
Keywords - Transfer path analysis, Principle component regression, Structure-borne
sound, Airborne sound.