Abstract
In recent years, customer has become very sensitive to noise levels in vehicle. Hence maintaining good acoustic ambience in vehicle cabin has become essential. Power Based Noise Reduction (PBNR) is one such effective tool that evaluates the acoustic performance of sound package in a vehicle and helps in improving the passenger comfort level. PBNR measurements using Dodecahedral Sound Source (DDS) requires very less time and efforts as compared to the traditional measurements done using Volume Velocity Source (VVS). The source strength evaluation with DDS using a particle velocity sensor seems to be more precise because energy levels measured using VVS altered with respective direction (±X, ±Y, ±Z) thus arising a question on computed source strength. The main objective of this study is to assess acoustic performance of a vehicle in mid-high frequency range (200 – 6300 Hz) for ensuring passenger comfort in cabin using dodecahedral sound source. This document shows a methodology to predict PBNR with respect to frequency using the dodecahedral sound source. PBNR measurements at identified cabin seating ear locations with respect to different source paths (engine, tire etc.) are carried out. A good correlation with 35% variation on an average is observed on comparison with the traditional VVS based PBNR calculation. It is concluded that PBNR measurements done using this methodology tend to closely match with the results of VVS. PBNR method which a static evaluation tool produced consistent results with less than 3% deviation as compared to traditional vehicle level dynamic testing approach which has higher fluctuations. This methodology optimizes the traditional experimental procedure by reducing time and efforts thus improving overall efficiency.