Toward an Objective Understanding of Perceived Glovebox Closure Sound Quality

As an essential dimension of product harmony and craftsmanship, product sound quality has drawn increasing attention from customers in recent years. To meet this customer requirement, Delphi Corporation has been taking a proactive role in understating customer preferences, improving designs, and developing a sound quality knowledge base for this purpose. This study investigates the characteristics of the glovebox closure sound that affects the customer's perception of the product harmony and craftsmanship. Previous research has indicated that the perceived closure sound quality is affected by the spectral balance, the occurrence of multiple impulses, and the duration of the closing event. The primary goal of this study is to explore how these parameters affect the perception of glovebox sounds and to what extent. A jury evaluation was conducted with a sequence of glovebox closure sounds, which were derived from an existing recording. The sound was modified by varying parameters that affect the spectral balance and multiple impulse characteristics (time between impulses and peak level of impulses). 38 subjects were selected through a hearing test, and participated in each session of the jury evaluation. Acceptability of the closure sound was derived from the subjective responses on a preference rating using a 9-point rating scale. The result indicates that the mean preference score decreases with the increase of both duration between impulse events and secondary peak level. The result also revealed that the closure sound becomes unacceptable when the duration between impulse events increased to 20 to 60 msec., depending on the peak level and the sharpness of the secondary impulse. This result will be used to establish an acceptance zone with varying degrees of spectral balance, impulse separation duration, and relative impulse amplitudes.