Title: Study on Test and Product Variations of Noise Reduction Capabilities of Headliners
text: This paper discusses the importance of studying different variabilities (test and product variations) that may affect the noise reduction capabilities of automotive headliners, constructed from different materials. For this purpose, interior noise measurements were made at a position approximating the operator ear level, with different headliner materials under various operating conditions. For better understanding of the effect of different variabilities on acoustical performance, various single number values were computed from the measured data reduced in 1/3 octave band frequencies. Statistical data analyses show that the acoustical performance evaluation of headliners is affected by the product variation from one headliner to another, as well as experimental variation due to vehicle performance and test variation.