Visualization of noise sources by transmission path analysis of air conditioner piping (Extraction of acoustic latent modes by operational TPA based on PLS)

This study examines Operational Transfer Path Analysis (OTPA) for vibration-acoustic dynamics in complex vehicle systems. OTPA simplifies data collection by avoiding structural transfer function pre-measurement, overcoming traditional method limitations on complex paths. It uses multivariate regression for transfer function estimation but faces noise and multicollinearity. Conventional PCR-based OTPA for vibration-acoustic coupling often misidentifies dominant sound contributors by prioritizing high-energy vibrations, potentially overlooking critical low-energy components or the low radiation efficiency of high-energy ones. To address this, a Partial Least Squares (PLS) regression-based OTPA is proposed. PLS extracts 'acoustic latent modes' by maximizing covariance between reference vibrations and response sound, better linking vibrations to acoustics. The PLS-OTPA is verified to extract key sound-constituting vibration modes and shows improved accuracy over PCR methods in analyzing an air-conditioning outdoor unit's piping. This approach significantly refines transfer path analysis accuracy, advancing vibration and acoustic analysis.