<div class="htmlview paragraph">This paper treats the engineering, optimization and tuning of vehicle sound absorption with emphasis on headliners. It covers the methodology of measuring sound. The mechanisms for sound reduction damping are discussed.</div> <div class="htmlview paragraph">The report compares the acoustical performance of worldwide headliner constructions at different frequencies and leaves it up to the reader to make his/her own evaluation. The Authors discuss means to enhance and optimize and tune headliners to increase the acoustic functionality of the parts. The paper also shows the relative acoustic performance of interior trim parts.</div> <div class="htmlview paragraph">Future trends and methodology are explored along with the European trend to eliminate roof bows and the headliner being robotically adhered to the roof to improve acoustics, structural effectiveness and lower cost.</div>