Abstract: The constant increase of quality standards for motor vehicles, due to the development of advanced technologies as well as process, design, production, and often imposed by specific rules, brings the car manufacturers to compete mainly on the quality level of vehicles.
Some studies converge on the thesis that the customer considers to be of “good quality” car which has a low level of noise inside the vehicle during the running. This led designers to consider closely the development of products oriented to the global reduction of noise. Major attention has been devoted primarily to the reduction of the noise of the engine, once considered as the main and sometimes only source of considerable noise. Reduced the contribution of the engine, became predominant the noise from transmission and especially from gear-box.
Therefore, the reduction of noise of motor vehicles currently has much importance. In particular, major attention is given to the part of the phenomenon produced by the gears. In a vehicle this noise can mainly be referred to the mechanical transmission, to the transfer of torque or is produced by the differential gear.
The geared noise occupies an important role of topic growing interest in the automotive field, until now considered to be one of the major design factors. Designers often try to reduce noise transmission paths by modifying the external structure of the gearbox and the inside soundproofing, although the optimal solution is to reduce, or even eliminate the sources of noise. In order to design less noisy units it is, therefore, necessary to know the origins and characteristics of noise starting from the gear-box.
The main function of the gear is to transmit power between a pair of wheels meshing as uniform and regular as possible. These conditions can be satisfied by a good configuration of the gearbox, a perfect tooth geometry, an infinite stiffness and softness of meshing. In practice there are many factors which can cause deviations from the ideal situation: the shape of the tooth as accurately realized, may not be ideal from a micro-geometrical point of view.
Besides, due to the hardness of the material, we can not think that the tooth and all transmission gears involved in the transport of torque are free of elastic tension, and therefore from deformation.
A gear-box generates a sound composed of discrete frequency tones of meshing gear, due to the number of teeth involved per revolution (order of meshing), and its harmonics. These frequency components, affecting the wheels, because the load is transmitted from a pair of teeth to another one, generate a noise known as Gear Whine. It manifests as a "whistle" or a "siren" and its influence on the overall vehicle noise is significant and must be strictly limited.
The parameters that mainly influence this phenomenon are: the transmission error, the friction forces and the peak to peak transmission error.

Brief Biography of the Speaker:
Vincenzo NIOLA is professor of Applied Mechanics at Naples University Federico II since 31 march 1987. After he got an Univerisity Degree in Mechanical Engineering, he started in january 1978 didactics activity as helper at course of Applied Mechanics and Machines et as member of their committee of examination. Since september 1979 he carried on that collaboration as owner of a scholarship from C.N.R. (National Research Council). Since december 1981 to march 1987 he was a researcher carrying on the practice course for Applied Mechanics, taking a part at examination meeting and working as proposer in many degree thesis. Since 1981 to 1984 he carried on his didactics activity as university teacher for Bioengineering course of locomotive apparatus at Orthopaedy and Traumathology specialization school of 2th Department of Medicine and Surgery of Naples University. Since 31 march 1987 is professor of Applied Mechanics at Naples University Federico II, and since A.A. 86/87 to A.A. 92/93 he carried on the Applied Mechanics and Machines course for electronic engineers, and since A.A. 93/94 to today carry on the Applied Mechanics course for computer science engineers. Since A.A. 88/89 to 89/90 he carried on as supply teacher the Applied Mechanics course for building engineers at Salerno Engineering University. By A.A. 94/95 to A.A. 97/98 he carried on as supply professor Tribology course at Naples University Federico II. By A.A. 2001/2002 he holds the chair of Applied Mechanics for University Degree of “Orthopaedic Technician” at 2th Department of Medicine and Surgery of Naples University. Since A.A. 2005/2006 is professor of Tribology and of Complements of Mechanics. During this years Prof. Vincenzo Niola has been the chairman of his courses examination meetings, and was proposer of many degree thesis.. During his activity Prof. Vincenzo Niola was owner of financings from MURST and (in past and present) cooperate scientifically with research corporation and national industries (MERISINTER, MONTEFLUOS, INDESIT, ALENIA, C.I.R.A.). He's scientific member of Naples research unit for PRIN 2003. He's fellow of Italian Association of Theoretical and Applied Mechanics (AIMETA). He's member of IFToMM Linkages on cams committee. He belongs to the International Scientific Committee of the "World Scientific and Engineering Academy and Society (WSEAS). He is President of the WSEAS Italy Chapter on the “Analysis of the Mechanical Systems”. He was been Chairman and "invited author" in some session of Internatinal Conferences. He's author of more than 150 national and international papers. Is author of two chapters in the international books. In the past he focused his research activity on :
• Applied Mechanics
• Tribology
• Robot dynamics
• Funicular Railways
• Static and dynamic behaviour of rotors on lubricated journal bearings
• Industrial robot calibration
• Analysis of Mechanical systems by means Wavelet Transform.
Prof. Niola is member of the “Editorial Board” of two International Journals. He is also Editor-in-Chief of a International Journal.
During these years he has also been speaker of a lot of invited plenary lectures in the International Conferences.