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Inside cabin of a passenger car, low frequency booming noise still presents a major hurdle for NVH engineers to fine tune a vehicle. Low frequency booming noise is presently taken care with addition of mass damper and large reinforcements. These conventional countermeasures add weight to the vehicle as well as increase the overall production cost. The study presented in this paper proposes a countermeasure model that not only reduces the booming noise but also avoids any weight and cost addition. It has been focused for low frequency booming noise around 30 ∼ 40 Hz. Within the range mentioned, one of the major reasons for booming noise in hatchback models is the bending resonance of backdoor. By modifying the mode of the backdoor in such a manner that it cancels the effect of bending on the vehicle acoustic cavity, improvement can be achieved in terms of sound pressure level at the driver’s right ear location (DREL).

Automotive OEMs quest for vehicle body light weighting, increase in Fuel efficiency along with significant cut in the emissions pose significant challenges. Apart from the effect on vehicle handling, the reduction of vehicle weight also results in additional general requirements for acoustic measures as it is an important aspect that contributes to the comfort and the sound quality image of the vehicle, thus posing a unique challenge to body designers and NVH experts. Due to these conflicting objectives, accurate identification along with knowledge of the transfer paths of vibrations and noise in the vehicle is needed to facilitate measures for booming noise dampening and vehicle structure vibration amplitude. This paper focuses on the application of a unique design and development of vehicle body structure anti-vibration dynamic damper (DD), unique in its aspect in controlling booming noise generated at a specific RPM range.

Interior sound quality is one of the significant factors contributing to the comfort level of the occupants of a passenger car. One of the major reasons for the deterioration of interior sound quality is the booming noise. Booming noise is a low frequency (20Hz∼300Hz) structure borne noise which occurs mainly due to the powertrain excitations or road excitations. Several methods have been developed over time to identify and troubleshoot the causes of booming noise [1]. In this paper an attempt has been made to understand the booming noise by analyzing structural (panels) and acoustic (cavity) modes. Both the structural modes and the acoustic modes of the vehicle cabin were measured experimentally on a B-segment hatchback vehicle using a novel approach and the coupled modes were identified.

Road/Tire noise is an important product quality criterion for passenger cars which are driving customers to decide upon the selection of a vehicle. Reduced engine noise and improvement in road conditions has resulted into more road/tire noise problem as average vehicle speed has gone up. Excitations from road surface travelling through the tire/suspension to vehicle body (structure-borne path) and air-pumping noise caused by tread patterns (air-borne paths) are the main contributor to tire noise issue inside the vehicle cabin [1]. A lot of emphasis is put on the component level design as well as its compliance with vehicle structure to reduce the cabin noise. The objective of this work is to establish a methodology for evaluating structure-borne road/tire noise by evaluating the tire structural behavior and its interface with the vehicle body and its suspension system and identifying the contributing critical paths.

Structure borne noise is the major source of noise inside the vehicle compartment. Recently the quietness of the occupant cabin has become an important dimension to the quality of product. OEMs are finding it challenging to meet the customer expectations for “Powerful yet quiet” attribute. Several focused studies have been made to reduce the under hood component noise in automobiles. This paper summarizes the optimization of vibro-accoustic sensitivity (VAS) of the engine mounts in passenger car engine. The contribution of each engine mount on the structure-borne noise transfer inside the cabin is studied by conventional FRF and normal mode analysis using Nastran, along with physical testing validation. This paper emphasizes to reduce the structure borne noise with the focus on weight reduction of the body side engine mount.

In the recent past, interior noise quality has developed into a decisive aspect for the evaluation of overall vehicle quality. The paper discusses the effect of structural modes of vibration caused in a passenger car during its operational conditions and its effect of noise inside the cabin. In order to characterize the body modes under road operation, OMA is used and the Interior noise quality of car cabin is judged by the Sound quality tools. Based on the jury evaluation, the problem is identified and problem area is identified with operational modal analysis techniques to take the countermeasure and verification of the study is done. The relation of body modes is established to overall cabin noise performance and improvements are checked with use of Modification Prediction tool after identifying the critical areas. This study is helpful in developing the new vehicle modal faster and also to analyze and to take countermeasure at earlier stages of developments.