Measurement, Judgment and Prediction of the Annoyance of the Noise Produced by Seat Belt Retractors

Abstract

The automobile industry has grown sustainedly over the past decade. To enhance competitiveness, user experience and product details increasingly receive attention. Squeak and Rattle (S&R) are noises caused by the relative motion between installed components, in terms of friction and impact. The perceived annoyance of squeak and rattle noise from seat belt retractors, as might be expected, is nowhere near the sense of annoyance from other more significant sources, for instance, tires and engine. However, such a sort of objective noise is still audible and might be more predominant in future cars which have much better sound isolation. In this thesis, three types of seat belt retractors are studied. They are both practically used inside Volvo cars. The primary objective is to design a sound quality metric for the squeak and rattle noise from seat belt retractors. While recording the sounds, different recording environments, including laboratories and actual in-car environments, are seriatim tested. In order to obtain the perceived annoyance level of objective noises, a series of listening tests are performed in the form of MATLAB graphical user interface (GUI), with participants from different backgrounds involved. The listening test results are then combined with calculated psychoacoustic characters of sounds, thereby designing the corresponding sound quality metric using multiple linear regression.