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An effective program for external noise reduction of vehicles was firstly established in Brazil by an agreement between ANFAVEA and CETESB in the beginning of last decade. IBAMA worked this proposition and published in 1993 the first CONAMA Resolution, including the pass-by noise limits and the deadlines to satisfy the new sound pressure levels. Since then, CONAMA is responsible for this subject. In 2001 lower levels were imposed, similar to those existing in Europe, with 2006 as the deadline for all vehicle families. The paper describes and gives and overview of the procedures, the acoustic technologies and improvements developed to achieve, in two steps, the new limits, mainly for commercial vehicles, like heavy trucks {from 92 dB(A) to 80 dB(A)} and passenger cars {from 84 dB(A) to 74 dB(A)}. We enumerate also the non-acoustic problems solved, for instance the thermal problems, due to the acoustic barriers applied to reduce pass-by noise.

The paper presents the concepts and applications regarding Articulation Index (AI) that is widely used in the automotive industry as a powerful parameter to qualify/quantify the middle and high frequency spectra associated to the internal noise of vehicles. We are able to show a short historical review including the today used definitions and calculations based in third octave band spectra through and idealized speech region model like our pioneer Brazilian standard. We show also other applications, where AI can be an excellent tool to evaluate vehicle acoustics. We emphasize the relation of AI to Speech Intelligibility and make considerations concerning other factors influencing Intelligibility. In addition we comment the integration we have produced with an overall noise parameter like dB(A) - (H-index) and the proposition of an AIM - Articulation Index Modified.

The conventional and fixed maintenance intervals planned according to the vehicle application group (rough operating condition, short haul and long haul) are substituted by computed intervals, which correspond to the real components wear. The system carries out the prognosis of different services for periodic maintenance, indicating in the instrument cluster the dates when the services should be carried out as well as the remaining distance for carrying out each service. The system allows to join all different maintenance dates to only one date, improving the vehicle programming. The FSS totally integrated with CAN (Controller Area Network) line through a telematic system can centralize all maintenance prognoses in the transport company. Using this system, the user can reduce all documents and maintenance vehicle controls.

The purpose of this paper is the presentation of the main experiences of customers and users of trucks and buses regarding the electronic systems placed in these vehicles, specially in the Latin American market. Basically, in the past years the number of on-board electronic devices increased a lot and the evolution of the customer know-how concerning the new technologies is in progress. Therefore, a line between the mechanical engine and the electronic vehicle management will be traced on this paper, considering the time the customers have taken to react regarding the applied innovations.

The paper looks for the degree of linear correlation of some acoustic parameters concerning Speech Intelligibility in vehicles. The Articulation Index (AI) was originally a criterion to characterize the influence of parasite noise on the Intelligibility of a conversation in the design of speech communication systems. Introduced in the automobile acoustics, it is more and more commonly used by vehicles manufacturers to estimate the middle and high frequency content of spectra noise inside various types of vehicles driven under several running conditions. The correlation with Speech Intelligibility, measured through subjective measurements is well known. Presently we have more sophisticated parameters like STI, RASTI, SII… directed mainly to architectural acoustics and sometimes used in vehicle acoustics. They require specific hardwares and softwares and are more complicated to deal with and often are called machine measures of Speech Intelligibility.