ccording to the World Health Organisation (WHO), noise is second only to air pollution in the impact it has on health. It is a major cause, not only of hearing loss, but also of heart disease, learning problems in children and sleep disturbance. Yet traffic noise could easily be halved, with existing technology, if more stringent limits were adopted.

In December 2011, the European Commission adopted a proposal for a new regulation aimed at tightening noise emissions standards for cars, vans, lorries and buses. Vehicle noise standards were last updated in 1996, so were long overdue.

Definition of the engine sound quality inside vehicle

This paper presents a way to quantify the acoustics quality of engine perceived inside the vehicle from the definition of sensors to the choice of acoustics parameters. Normalized metrics like loudness or sharpness are used to give a global feeling of the acoustics quality. Three other acoustics parameters are introduced, they are linked to well-known phenomena: modulation and whistling due to the driving belt, shock balance for the piston slap. The engine is measured in three typical conditions where those characteristics can occur: low idle with cold and warm diesel engines, run-up condition from low idle to 2500 rpm.

A wheel bearing is a set of steel balls held together by a metal ring called a race. They help wheels spin fast with as little friction as possible. They are used on all kinds of vehicles, from bicycles to aircraft and cars.

The sound package materials for vehicle noise control seminar provides a detail and thorough analysis of three different classes of acoustical materials – namely absorbers, barriers, and dampers, how they are different from each other, and acoustical properties that materials should possess for optimum vehicle noise control. The seminar addresses new advances in acoustical materials, primarily in absorption materials that impact the vehicle acoustics. The seminar covers ways to evaluate the acoustical performance of these materials using different test methods, including material, component, and vehicle level measurements.