Impact of Liquid Applied Sound Damping Treatments on Sound Quality as Measured via Psychoacoustic Metrics

Electric vehicles (EVs) are quickly growing their share of the auto market and have a much different acoustic environment than their internal combustion engine (ICE) precursors. The electric drivetrain typically results in lower magnitude broadband noise than an ICE vehicle but can produce annoying, high-frequency tonal sounds particularly noticeable to the human ear. Psychoacoustic metrics aim to characterize sounds based on human perception and have increasingly been employed to understand what noises within an EV may be considered undesirable and in need of additional acoustic treatment. Liquid applied sound damping (LASD) coatings are one method employed to minimize unwanted noises within a vehicle. LASD is typically applied to metal components of the vehicle body to dampen vibrations in the structure through its viscoelastic properties. LASD formulation, application, and polymer design has previously been shown to have a strong impact on the material’s damping performance at different frequencies. Herein, we investigate how those same variables affect the resulting sound emanating from vibrating panels coated with these materials, with particular attention to the psychoacoustic profile produced. Tying LASD design to psychoacoustic improvements will help show which material choices will be best suited for EV applications in the future to address these vehicles’ unique acoustic environment.