Passenger Vehicle Saloon Noise Prediction Using Acoustic Transfer Function Measurement Based Model

New legislation’s, competition from global players and change in customer perception related to comfort parameters are key factors demanding manufactures to design and manufacture vehicles with very low saloon noise levels. The main causes for higher noise levels at passenger saloon compartment can be attributed to source noises (Powertrain, Driveline, Intake and Exhaust etc.), acoustic isolation and structural sensitivity of the body. Out of all above parameters, powertrain noise and acoustic isolation are two critical parameters effecting interior noise performance. This paper is an attempt to explain acoustic source contribution analysis through transfer function measurement in a passenger vehicle. Acoustic transfer function between engine bay and passenger ear level was measured using reciprocity technique (reciprocal method) with reference source placed at various locations inside the vehicle. A mathematical model is developed to predict saloon noise level using transfer function and powertrain near source noise level data at operating condition. In this paper passenger saloon noise level prediction is done based on transfer function based model and compared with measured noise level measured at same receiver location using microphone. A good level of co-relation is achieved between predictions and measurement. This model will be useful to estimate interior saloon noise levels (contribution of powertrain alone) at development stage which could save time and cost. In future similar modeling method could be deployed for other acoustic source for more accurate prediction and contribution analysis.