Tor Kihlman

City traffic noise - a local or global problem?

According to the EU Green Paper on Noise policy, approx. 20% of the EU population is exposed to outdoor noise levels exceeding 65 dB (equivalent A-weighted daytime levels) and a little more than 40% is exposed to levels between 55 and 65 dB. The main source is then city traffic noise caused by cars, trucks, buses, trams, and trains. The situation in other industrialised countries is very much similar. This actual situation should be compared to the longterm goal for maximum noise exposure of the citizens. These goals are in most cases formulated as outdoor equivalent levels; in some cases as 24 hour levels, in others in separate daytime and nighttime levels. In several countries in Europe the goal implies 24 hour levels of the order LAeq<55 dB. This corresponds to a situation where a substantial fraction of the population is judged to be annoyed or seriously annoyed by the noise. To achieve this goal, it is demanded to accomplish a typical noise reduction of the order of 10 dB or more. For dwellings facing main roads the necessary noise reduction is of the order 20 dB. For the covering abstract see IRRD E104312.

Exploit the soundscape and reformulate traffic noise goals

‘‘Soundscape support to health’’ (www.soundscape.nu) is a 4 year research program including studies of traffic noise propagation in cities and different health effects of traffic noise. Special attention is given to the effect of access to a quiet side of dwellings. One goal of the program is to find more relevant goals than the present longterm general goal LAeq,24h<55 dB for all residents which on one hand is unrealistic and on the other hand does not imply a good environment—it is a compromise; at this level a substantial fraction of an exposed population is highly annoyed. However, the big spatial SPL variations within the city typically ranging from 40–70 dB can be systematically exploited. Traffic noise goals should therefore be reformulated to protect existing quietness and promote that all residents get access to a quiet environment within reach even though a typical level at facades facing the traffic will exceed 60 or 65 dB during a foreseeable future. In the paper how the results from the progr...

Quiet areas and quiet facades: Important elements in the EU Noise policy

The long‐term goal for road traffic noise, Lden<55 dB, cannot be reached for all dwellings either in sprawled or in compact cities during the foreseeable future [T. Kihlman and W. Kropp, ‘‘Limits to the Noise Limits,’’ ICA, Seattle 1998]. What, then, can be done to improve the situation? One strategy is to exploit the spatial noise level variations. Even though many dwellings are exposed to Lden=65–70 dB, outdoor levels in the range 40–50 Lden are not rare in the cities: courtyards in European cities being the typical case. The EU draft directive on ambient noise puts emphasis on the protection of quietness. Quiet areas and ‘‘quiet facades’’ shall be shown on noise maps. The concept of a relatively quiet facade has been introduced. Questions to answer are: What are the effects on the annoyance and sleep disturbance when dwellings have one noisy and one quiet side? To what extent do existing, noise‐exposed dwellings also have a quiet side? What are the potentials to increase also at low cost—the access to ...

Noise and hearing studies in shipyards

An ambitious project for the improvement of the total working environment (noise, dust, light, accidents, etc.) has been going on for more than 1 year at Giitaverken shipyard in Goteborg. The project is motivated by the fact that the present environment involves unacceptable risks for health and safety. It is necessary to make considerable improvements in noise abatement, as many of the employees have and are still sustaining hearing losses. Giitaverken shipyard employs about 7000 people. Large sections of the ships are built in different halls. They are fitted together in one enormous hall, with a volume of 580,000 m3. This means that most of the work is performed indoors. As far as noise is concerned, the project includes studies of and treatment against intermittent noise with very frequent impulsive noise of high levels. The main noise sources are the bangs of sledgehammers and pneumatic tools for removing slag from the welded joints and other pneumatic tools for adjusting the steel plates relative to each other before welding. Our work has so far involved the following parts: (1) physical measurements for judging the risk for hearing impairment and evaluation of the halls where means for reducing noise are most urgent; (2) studies of the different noisy tools and work processes, considering possibilities of improving the tools from a noise point of view and/or change of working methods: (3) start of a continuous hearing conservation program. including regular audiometry; (4) studies of the effect of noise-induced high-frequency hearing loss in everyday listening situations. The noise situation is different for the different occupational groups, and the situation also changes from day to day. Typically, the work is performed in a large number of two-worker groups. The noise exposure is highest for the platers, followed by the welders. The total noise exposure for each worker is determined both by his own work and the work performed by all the others in the hall. The reason for the variation from day to day is that the noise situation changes

Noise responses before and after noise abatement measures in a residential intervention project

In a residential area exposed to road traffic noise a socio-acoustic longitudinal study was conducted to investigate the effects of a large intervention project on acoustical conditions and residents noise responses. The paper presents results on general noise annoyance, noise disturbed activities and perceptions of the sound environment in relation to obtained noise levels before and after the interventions. The most comprehensive abatement measures implemented were construction of new buildings that filled in gaps between buildings facing the highway and erection of a noise barrier to create less noise-exposed court- yards and sides of the dwellings. One building site had a considerable renovation, such as installation of new windows, glazed-in balconies, and an upgrading to two-sided flats with windows facing the quieter courtyard. Overall in the resi- dential area, noise levels were reduced with 5–10 dB at the most traffic exposed side and with 4–10 dB at the less noise exposed side. General noise annoyance and sleep disturbances decreased substantially and the perceived sound environ- ment indoors and outdoors was improved for a majority of the investigated building sites. Through the successful combination of measures taken in the res- idential area, we obtained significant positive effects; however, measures to fur- ther reduce the negative impacts of noise on health and well-being and to improve the sound environment are needed and suggested.

Noise Policy-integration with climate and natural resource policies

Climate change policy is difficult. Noise policy is even more difficult because of its complexity. There is such a wide range of society’s processes/activities in which noise problems are integrated. There are win/win situations. Lower noise emissions facilitate healthy quiet compact cities. Compact cities save land use and fuel, have typical shorter travelling distances, lower speeds are possible. Barrier effects can be reduced. Walking and bicycling can be promoted. There are conflicts. Demands upon reduced fuel consumption and cleaner exhaust gases from road vehicles and jet engines make the noise emission problems tougher. Traffic safety demands on roads may collide with ways to reduce the noise emissions. Politicians in national and international bodies call noise a local problem which, however, local politicians cannot solve if not the source levels get reduced which is an area for international agreements. National industrial interests delay progress towards quieter products. Economic sub-optimization lead to unfortunate end results. To get a really quieter world demands that planners, builders, industries, etc. all do more. Speed policy is an important area. Few politicians understand the real complexity of the noise problems. We, noise professionals, have to spend more time on teaching and influencing them.

William W. Lang’s contributions to the development of the International Institute of Noise Control Engineering

Bill Lang has been a member of the Board of I‐INCE since its first meeting in 1975 in Sendai, Japan. From 1988 to 1999 he served as the President, and to this day remains a very active member of the Board. The INTER‐NOISE congress series has been the core activity of I‐INCE, and in every case Bill has contributed very actively to secure an excellent congress. He has also taken a number of initiatives both to improve the organization itself and to develop new activities, especially the Technical Study Groups that have prepared consensus reports on important issues such as noise barrier effectiveness and industrial noise hearing conservation policy. At present, he is very active in attempting to develop a global noise control policy.

Soundscape in cities, limits to the noise limits?

Today traffic noise due to cars, trains, and airplanes is the main noise source in urban areas. In accordance to the European Commission’s Green paper on Future Noise Policy, more than about 250 million people are exposed to A‐weighted outdoor levels higher than 55 dB. To improve the situation is a tremendous challenge and the question arises if we are really able to provide a good environment (i.e., levels below 55 dB) for all people in today’s cities. In a previous paper [Kihlman and Kropp, Proceedings International Congress on Acoustics, Seattle (1998)], different cities with different structures and automobile dependencies are compared in a general study based on statistical data. A flat regular town structure was assumed without shielding due to, for instance, buildings. In this paper the studies are extended to more common situations including detailed information about traffic flow and the screening of traffic noise due to the building structure. Results are compared with sound maps for different c...

A library of visualization and auralization examples to support understanding

In a project financed by the Swedish Council for renewal education a library has been produced containing visualization and auralization examples concerning physical phenomena in acoustics. The main goal of the library is to support the development of a thorough understanding of basic acoustic phenomena. The work was supported by studies in the form of interviews and questionnaires to understand—What are the genuine problems students have in acoustics, mathematics, and physics? How do the students’ and teachers’ view of acoustics, physics, and mathematics differ? What are suitable measures to achieve a common basis between teacher and student for a successful communication? During the project it became obvious such a library has to be developed together with students from our courses. The library has to be adapted to the students needs and to their mental picture of physics, mathematics, and acoustics. In order to achieve this, a group of students was asked to take part in the project. They directed both ...

The influence of identical room dimensions on the sound insulation at low frequencies

At low frequencies the sound insulation between rooms is only valid for the specific case under consideration as shown in works by different authors. The expression ‘‘low frequencies’’ implies a frequency range where the rooms’ dimensions are comparable with the wavelength of sound in the rooms (i.e., normally below about 250 Hz for normal rooms). Both theoretical studies as well as experimental studies in the laboratory show that there is a substantial decrease of the sound insulation when the dimensions of the sending and receiving rooms coincide. The question arises if this decrease of the sound insulation can also be observed for the sound insulation of partitions in the field. The results are often biased by other effects such as flanking transmission or smaller differences in the fabrication of the partitions. By means of statistical studies field measurements are analyzed to show the influence of the room dimensions on the sound insulation in the field. To avoid the deterioration of the sound insul...