Pass-by Source Path Contribution

BK Connect® Pass-by SPC helps you investigate the contribution of noise sources such as tyres, engine/motor, exhaust, to the overall pass-by noise.

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Source Path Contribution (SPC) analysis is a technique for evaluating noise contributions from suspected sound or vibration sources through various acoustic or vibroacoustic paths to a desired receiver location. Dominant sources with respect to a given receiver can be highlighted to help focus engineering effort where it has the greatest effect. While SPC methods are often used for interior cabin noise analysis with sources and paths being both acoustic and vibratory, BK Connect Pass-by SPC is specially designed for pure acoustic analysis using measurements from an indoor pass-by setup. 

Unlike some other solutions, BK Connect’s SPC methods calculate source contributions explicitly, rather than breaking down the measured total sound into contributions. By comparing the sum of contributions with the original overall measured data, you get a true validation of the model with results that are obtained independently of each other. A close match gives confidence in the modelling assumptions, which is important when using SPC for making real engineering decisions such as in design optimization or problem resolution.


  • Perform source path contribution analysis (acoustic transfer functions and operating conditions) to evaluate source contributions to vehicle pass-by noise
  • Ranking of contributions to pass-by noise
  • Evaluation of design alternatives and their effects on pass-by noise emission
  • Gain insights on root causes and potential solutions of pass-by noise problems
  • SPC-based tyre noise correction of indoor pass-by simulations using outdoor track measurements
  • Contribution analysis in conjunction with VI-grade NVH Simulator or Insight Type 8601-S
  • Management and sharing of large amounts of SPC data (measurement, calculation, and analysis) in an indexed, sharable, file-based database


  • Task-oriented, user-friendly software
  • Offline setup in Microsoft® Excel® with one-step import to BK Connect for quick start-up
  • Acoustic transfer function matrix validation tool to help optimize conditioning for SPC analysis
  • User control of calculation frequency range
  • Frequency-dependent control of condition number threshold to minimize inversion errors
  • Component source grouping tool with the ability to control the order of analysis and minimize crosstalk errors
  • Ability to import field pass-by data for results comparison or tyre noise calculation
  • Network-based data file sharing in Team Server using a common file repository
  • Report to Excel for flexibility of downstream reporting and export time data for post-analysis, such as order extraction or narrowband spectral analysis with BK Connect
  • Multiple file formats supported for acoustic transfer functions (ATFs) and operating data
  • Results presented in Pass-by Viewer for comparison with regulation field (outdoor) and indoor pass-by noise tests
  • Results management using Team Server enabling comparison of pass-by results from any test source