Feasibility of Using a Mobile Device to Identify the Axle Whine Noise in a Vehicle

This article investigates the feasibility of using the built-in microphones of mobile devices to diagnose axle whine noise in a vehicle. Three sound pressure measuring sensors or devices are selected. The first one is a highend condenser microphone, which is calibrated during the measurements; this data is taken as a reference for the other devices. Then two different types of mobile devices are selected and relative calibrations are carried out. Measurements are first performed inside a hemi-anechoic room; artificially generated sinusoidal and random sound signals are played through a calibrated sound source and data is acquired with all devices. This setup is placed inside a vehicle cabin (for a non-running engine) and measurements are repeated. The onboard entertainment system of the vehicle is used as well in addition to the calibrated sound source. Measurements reveal that one of the mobile devices has superior performance when compared to the other one though calibration improves the performance of the latter. Finally, measurements are performed inside the vehicle cabin while the vehicle is being driven along a certain path to assess the diagnostic performance. The axle whine noise problem in two vehicles is successfully detected by employing an empirical mode decomposition process.