General view of road traffic noise problem

Road traffic noise is one of the typical community noise problems all over the world. To mitigate this environmental problem, noise reduction technologies for road vehicles, tires, road surfaces , road structures, and sound insulation of roadside buildings are essential conditions and at the same time legislative and administrative systems for this noise problem need to be well established. In this paper, the present situations of these factors are reviewed by giving examples mainly in Japan.

This lecture presents an historical overview of the development and application of methods to value nuisance from transportation noise. The main focus is on the recent application of stated preference techniques and the additional insights they can offer relative to the more traditional revealed preference approaches. The paper draws on studies undertaken by the author and colleagues to value road traffic noise in Edinburgh and Lisbon; aircraft noise in Manchester, Lyon, Bucharest and Athens and the wider literature. Issues discussed include: the representation of changes in noise levels to respondents; the design of stated preference surveys; the derived values of noise; the determinants of variation in noise values; the potential and actual applications of the values and future opportunities to further develop and apply valuation methods.

Harmonization of indicators, noise mapping and action plans deliver basic administrative information not only for noise abatement in highly noise polluted areas but also for comparisons across European countries. However, such activities do not provide any tools or essential knowledge for more demanding tasks which are required for the design and planning of sustainable environments which are supportive to wellbeing and health.

Without the knowledge of the determining factors behind the dose-response curves the decision process for the development of “action plans” is narrowed down. Furthermore, optional courses of action to handle the noise problem cannot be sufficiently considered. Therefore, there is the need for an approach which involves diverse fields of practice and diverse interdisciplinary interests related to people’s expertise in the respected areas. The multidimensional Soundscape approach puts emphasis on the way the acoustic environment is perceived and understood by the individual and by society (ISO /TC 43/SC 1/WG 54). The implementation of the Soundscape approach accounts for people’s concerns and integrates the noise-exposed people as local experts.

Currently, the Soundscape approach and its further development have been supported by many studies. Moreover, there is the European COST Action TD 0804 which creates a network among European Soundscaping by integrating Soundscape experts from all over the world. The ISO/TC 43/SC 1/WG 54 has started to work on finding definitions which refer to evaluation procedures. Soundscape has been moving ahead in city planning and has been collaborating with the “new experts”.

Transportation activities are one of the most commonly occurring sources of noise outdoors. Noise levels from these transportation sources are not usually sufficiently high to cause permanent hearing loss in communities affected, but they may cause considerable annoyance and activity interference. For example, a large number of persons worldwide are exposed to outdoor time-average A-weighted sound levels greater than 65 dB. The use of barriers has proven an effective method of abating transportation noise. A recent I-INCE Working Party concluded that the most common values for insertion loss range between about 5 to 12 dB. Barrier height is of fundamental importance to the effectiveness of a barrier. Proximity of source/receiver relative to the barrier is also of fundamental importance to the insertion loss provided by a barrier. Sound-absorbing material may provide addition insertion loss. Parallel barriers can degrade the performance of the single barrier; however absorbent material can be used to recover some of the loss in performance. Finally, atmospheric effects can degrade the performance of a barrier and places an upper limit on the amount of insertion achieved outdoors. This lecture will review the various factors affection the effectiveness of noise barrier.

Hearing Protectors: Noise Attenuation and Comfort

In many industrial and military situations it is not practical or economical to reduce the noise to levels that do not present either a hazard to hearing or annoyance. In these situations, personal hearing protection devices are capable of reducing the noise by up to around 40 dB. Although the use of a hearing protector is recommended as a temporary solution, until action is taken to control the noise, in practice, it ends up as a permanent solution in most cases. Therefore, hearing protectors must be both efficient in noise attenuation and comfortable to wear. Comfort in this case is related to the acceptance of the user to wear the hearing protector consistency and correctly at all times. The purpose of this paper is to review publications related to earmuff noise attenuation techniques and comfort. A review of the standards for noise attenuation measurement is presented. This paper will also presents a new quantitative indices based on the comfort parameters, mainly a novel measurements of the contact pressure distribution between the earmuff cushions and circumaural flesh of the human head. The comfort parameters were investigated and equations developed to calculate comfort indices and overall quality indices based on the contact pressure distribution measurements. The calculated indices are correlated with subjective evaluations.